KR20170112475A - Polyimide resin composition having improved frictional property and Film thereof - Google Patents

Abstract

The present invention relates to a polyimide resin composition and a film thereof, and more particularly, to a polyimide film having a protruding structure on its surface, which can improve the friction characteristics of the film while maintaining optical properties, Transparent electrode films, optical communication materials, protective films for solar cells, flexible display substrates, and the like.

Description

TECHNICAL FIELD The present invention relates to a polyimide resin composition having improved friction characteristics and a film thereof.

The present invention relates to a polyimide resin composition having improved friction characteristics and a film thereof.

Generally, polyimide (PI) resin refers to a high heat-resistant resin prepared by preparing a polyamic acid derivative by combining an aromatic dianhydride with an aromatic diamine or an aromatic diisocyanate in solution and then dehydrating it by ring-closure dehydration at a high temperature. (PMDA) or biphenyltetracarboxylic acid dianhydride (BPDA) or the like is used as an aromatic dianhydride component, and examples of the aromatic diamine component include oxydianiline (ODA), p (P-PDA), m-phenylenediamine (m-PDA), methylene dianiline (MDA), and bisaminophenylhexafluoropropane (HFDA).

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, , An insulating film, a semiconductor, and an electrode protective film of a TFT-LCD. Recently, a display material such as an optical fiber or a liquid crystal alignment film and a conductive filler are contained in a film or coated on the surface to be used as a transparent electrode film.

However, since the polyimide film is colored in brown or yellow due to its high aromatic ring density, it has a low transmittance in the visible light region and a yellowish color, which lowers the light transmittance and is difficult to use in fields requiring transparency. It has a lower Tg (glass transition temperature) than that of a conventional yellow polyimide film, and thus it is difficult to use in a field requiring a high temperature of 300 ° C or higher.

To solve this problem, attempts have been made to polymerize and purify monomers and solvents with high purity, but the improvement of the transmittance is not significant. When monomers having a rigid structure are used to impart thermal stability, the transmittance becomes significantly worse or the yellowness A phenomenon that has increased.

U.S. Patent No. 5,053,480 discloses a method of using an aliphatic cyclic dianhydride component instead of an aromatic dianhydride. In comparison with the purification method, there is an improvement in transparency and color in the case of a solution phase or a film, And thus the high transmittance was not satisfied and the thermal and mechanical properties were deteriorated.

U.S. Patent Nos. 4595548, 4603061, 4645824, 4895972, 5218083, 5093453, 5218077, 5367046, 5338826. 5986036 and 6232428 and Korean Patent Laid-Open Publication No. 2003-0009437 disclose monomers having a backbone structure connected to a linking group such as -O-, -SO ₂ -, or CH ₂ - and the like at an m-position other than the p-position There has been reported a novel structure of polyimide having improved transparency and color transparency as far as the thermal property is not significantly deteriorated by using aromatic dianhydride dianhydride and aromatic diamine monomer having a substituent such as -CF ₃ , Mechanical properties, yellowing degree and visible light transmittance are not enough to be used as a substrate for a semiconductor insulating film, a TFT-LCD insulating film, an electrode protecting film, and a flexible display.

In addition, the polyimide film has a low coefficient of friction and a high coefficient of friction. This may cause slip phenomenon when the films stick to each other or pass through the roll, causing scratch defects on the film. In addition, when foreign matter or air is introduced into the winding process, air pockets are generated between the films, and due to the surface characteristics of the polyimide film, it is difficult to remove the air pockets. In order to solve this problem, it is necessary to minimize the air pocket phenomenon by making a proper projection structure on the film surface.

An object of the present invention is to provide a polyimide resin composition and a film thereof having improved friction coefficient characteristics having a protruding structure on the surface while maintaining optical properties.

Accordingly, the present invention provides, as a first preferred embodiment, a polyimide resin copolymerized with dianhydride, an aromatic dicarbonyl compound and a diamine, a first silica having a particle size of 0.05 to 0.3 탆 and a second silica having a particle size of 2.3 to 5 M < 2 >.

       The content of the first silica particles is 0.01 to 0.05 parts by weight based on 100 parts by weight of the polyimide resin, and the content of the second silica particles is 0.008 to 0.016 parts by weight based on 100 parts by weight of the polyimide resin .

The dianhydride according to this embodiment may be selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydride (6FDA), biphenyltetracarboxylic dianhydride (BPDA) Dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellitic acid dianhydride (PMDA) , Benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), biscarboxyphenyldimethylsilanediamine hydride (SiDA), bisdicarboxyphenoxy diphenylsulfide dianhydride (BDSDA) , Sulfonyldiphthalic anhydride (SO ₂ DPA), isopropylidene is at least one selected from phenoxy bisphthalic anhydride (6HBDA) and a group thereof.

The diamine according to this embodiment may be selected from the group consisting of oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p- methylenediamine (pMDA), m- The reaction was carried out in the same manner as in Example 1 except that phenoxybenzene (133APB), bisaminophenoxybenzene (134APB), bisaminophenoxyphenylhexafluoropropane (4BDAF), bisaminophenylhexafluoropropane (33-6F), bisaminophenylhexafluoropropane (14CHD), cyclohexanediamine (14CHD), bisaminophenoxyphenyl (44CF), bis-aminophenylsulfone (4DDS), bisaminophenylsulfone (3DDS), bistrifluoromethylbenzidine (TFDB), cyclohexanediamine Propane (6HMDA), bisaminohydroxyphenylhexafluoropropane (DBOH), bisaminophenoxy diphenylsulfone (DBSDA), bis (4-aminophenyl) fluorene (FDA), bis Phenyl) fluorene (F-FDA) and one or more of these groups.

The aromatic dicarbonyl compounds according to this embodiment can be prepared by reacting terephthaloyl chloride (TPC), terephthalic acid (TPA), isophthaloyl dichloride (IPC), 4,4'-benzoyl chloride (BZC) It is more than one selected.

The present invention also provides, as a second preferred embodiment, a polyimide film produced from the polyimide resin composition.

The polyimide film according to this embodiment has a static coefficient of 0.2 or less.

The polyimide film according to this embodiment has a haze of 2.0% or less, an optical transmittance at a wavelength of 550 nm of 87% or more, a coefficient of thermal expansion (CTE) at 50 to 250 ° C of 50 ppm / The yellowness degree is 5 or less as a standard.

The present invention also provides, as a third preferred embodiment, a substrate for a display element comprising the polyimide film.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a polyimide resin composition and a film thereof having improved friction coefficient characteristics while maintaining optical properties.

Hereinafter, the present invention will be described in more detail.

One embodiment of the present invention is a polyimide resin composition comprising a polyimide resin copolymerized with dianhydride, an aromatic dicarbonyl compound and a diamine, a first silica having a particle size of 0.05 to 0.3 탆 and a second silica having a particle size of 2.3 to 5 탆 And to provide a polyimide resin composition containing silica.

The particle size is measured by the following method.

≪ Particle size measurement method &

(DMF) or dimethylacetamide (DMAc) as a solvent at 20.0% by weight and then subjected to an ultrasonic treatment for 1.5 hours. The dispersion thus prepared was injected into a Microtrac S3500 particle size analyzer And the mean value was calculated.

The present invention can improve the friction characteristics of the polyimide film when the first and second silica particles are included.

Describing this in more detail, in order to improve the friction coefficient of the polyimide film, it is necessary to determine the particle size and the addition amount of the silica particles reflecting the friction coefficient characteristics. Even if the particles are dispersed on the polyimide resin by ultrasonic waves or various kinds of mills due to the particle size and cohesion of the silica particles themselves, it is difficult to expect uniform dispersion due to sedimentation or aggregation of the particles. In addition, due to polyimide process characteristics, it is necessary to select silica particles to obtain the intended surface structure, for example, a protrusion-like shape on the surface of a polyimide film, without decomposing at high temperatures.

Accordingly, in the present invention, the first silica having a particle size of 0.05 to 0.3 탆 and the second silica having a particle size of 2.3 to 5 탆 are included, and when the friction coefficient is measured by the following method, the static coefficient is preferably 0.2 or less The polyimide film satisfies the physical properties of 0.1 or less, more preferably 0.01 to 0.1.

≪ Measurement of Friction Coefficient >

The LLOYD FT1 Friction Tester was used to measure the coefficient of friction of the film, and the Sled weight was measured at a moving speed of 100.0 mm at a speed of 250.0 mm / min, an area of 63.0 × 68.0 mm, and a weight of 280 gf. At this time, the material of the sled face and the base face were arranged in the same film.

The first silica particles according to the present invention preferably have a particle size of 0.05 to 0.3 탆. When the particle size of the first silica particles is within the above range, the dispersibility is excellent and the optical characteristics are hardly affected.

It is preferable that the second silica particles have a particle size of 2.3 to 5 占 퐉. When the particle size of the second silica particles is within the above range, the dispersibility is excellent, and surface protrusions are easily formed, and a desired coefficient of friction can be secured easily.

In accordance with the present invention, it is possible to form the protrusions having different height by including the first and second silica particles having the particle size, on the surface, and to provide appropriate roughness without affecting the optical characteristics, Can be formed.

The content of the first silica particles is 0.01 to 0.05 part by weight based on 100 parts by weight of the polyimide resin. When the content of the first silica particles is less than 0.01 part by weight, there is a problem that the number of low projections is insufficient and the film adhesion is increased. When the content of the first silica particles is more than 0.05 parts by weight, there is a problem that haze becomes high due to silica scattering.

The content of the second silica particles is 0.008 to 0.016 part by weight based on 100 parts by weight of the polyimide resin. If the content of the second silica particles is less than 0.008 parts by weight, the surface projection effect can not be expected. If the content of the second silica particles exceeds 0.016 parts by weight, the film haze increases.

In the present invention, the first and second silica particles having the particle size size are included in a combination of the contents as described above to form a projection having a different height on the film surface within a range in which optical characteristics are not lowered, Effect can be obtained.

When the dispersion concentration of the silica particles relative to the solvent is less than 0.01% by weight, the solid content is low, which makes it difficult to produce a film. When the concentration of the silica particles in the solvent is less than 0.01% by weight, %, The dispersibility in the polyimide resin solution may be lowered due to the aggregation and sedimentation of the particles in the dispersed solution.

In this case, the solvent to which the silica particles can be dispersed may be the first solvent used in the polymerization reaction of the polyamic acid described later in terms of workability. Examples thereof include m-crossover, N-methyl-2-pyrrolidone ), Dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO), acetone and diethyl acetate.

On the other hand, the polyimide resin according to the present invention is obtained by obtaining a polyamic acid solution in which a dianhydride, an aromatic dicarbonyl compound and a diamine are copolymerized, partially imidizing the obtained polyamic acid solution, Precipitation, filtration and drying to obtain a polyimide solid. The polyimide film may be prepared by mixing silica particles dispersed in a solvent with the solid polyimide obtained and imidizing it.

The dianhydrides which can be used in the present invention include 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA), biphenyltetracarboxylic dianhydride (BPDA), 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellitic acid dianhydride ), Benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), biscarboxyphenyldimethylsilanediamine hydride (SiDA), bisdicarboxyphenoxy diphenylsulfide dianhydride (BDSDA ), Sulfonyldiphthalic anhydride (SO ₂ DPA), isopropylidene is phenoxybisphthalic anhydride (6HBDA), and the type is not limited thereto. The dianhydride may be used singly or in combination of two or more, but is not limited thereto.

On the other hand, as the diamine used in the present invention, oxydianiline (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p-methylenediamine (pMDA), m- , Bisaminophenoxybenzene (133APB), bisaminophenoxybenzene (134APB), bisaminophenoxyphenylhexafluoropropane (4BDAF), bisaminophenylhexafluoropropane (33-6F), bisaminophenylhexafluoro (14CHD), cyclohexanediamine (14CHD), bisaminophenoxine (14CHD), bis-aminophenylsulfone (4DDS), bis-aminophenylsulfone (3DDS), bistrifluoromethylbenzidine (4-aminophenyl) fluorene (FDA), bis (4-aminophenyl) fluorene, bis (aminophenyl) 3-fluorophenyl) fluorene (F-FDA), or the like, And it does not limit a kind referred to this.

      Examples of aromatic dicarbonyl compounds usable in the present invention include terephthaloyl chloride (TPC), terephthalic acid (TPA), isophthaloyl dichloride (IPC), 4,4'-benzoyl chloride (BZC) The same ingredients may be mentioned but not limited thereto.

In the present invention, when the aromatic dicarbonyl compound is included, it has a benzene ring, and thus it has an advantage that high thermal stability and mechanical properties can be realized.

       The molar amount of the dianhydride and the aromatic dicarbonyl compound and the molar amount of the diamine are preferably such that the molar amount of the dianhydride and the aromatic dicarbonyl compound is in an equimolar amount, and the polyamic acid solution may be prepared by dissolving the dianhydride and the aromatic dicarbonyl compound in a first solvent.

      The reaction conditions are not particularly limited, but the reaction temperature is preferably -10 to 80 占 폚, and the reaction time is preferably 2 to 48 hours. It is more preferable that the atmosphere is an inert gas atmosphere such as argon or nitrogen during the reaction.

The organic solvent for the solution polymerization reaction of the above monomers is not particularly limited as long as it is a solvent dissolving the polyamic acid. As known reaction solvents there may be mentioned m-cresol, N-methyl-2-pyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethylsulfoxide (DMSO) At least one polar solvent selected from ethyl formamide (DEF), diethylacetamide (DEA), propylene glycol monomethyl ether (PGME), and propylene glycol monomethyl ether acetate (PGMEA) is used. In addition, a low boiling point solution such as tetrahydrofuran (THF), chloroform or a low-absorbency solvent such as? -Butyrolactone may be used.

These solvents may be used alone or in combination of two or more.

The content of the organic solvent is preferably 50 to 95% by weight, more preferably 70 to 90% by weight in the total polyamic acid solution in order to obtain the molecular weight and viscosity of an appropriate polyamic acid solution, Is more preferable.

The polyimide resin prepared by imidizing the polyamic acid solution thus prepared preferably has a glass transition temperature of 300 ° C or higher but may be lower in temperature depending on the constitution of the raw material used.

The method for producing the polyimide film from the polyamic acid solution obtained is not particularly limited, and conventionally known methods can be used. As the imidization method of the polyamic acid solution, thermal imidization method and chemical imidization method can be mentioned, and it is more preferable to use the chemical imidization method. More preferably, the solution subjected to the chemical imidation method is subjected to precipitation, followed by purification, drying, and then dissolving in a solvent. This solvent is the same as the above-mentioned solvent. In the chemical imidization method, a dehydrating agent represented by an acid anhydride such as acetic anhydride and a imidization catalyst represented by tertiary amines such as isoquinoline, p-picoline, and pyridine are applied to a polyamic acid solution. The thermal imidation method can be used in combination with the chemical imidization method, and the heating conditions can be varied depending on the type of the polyamic acid solution, the thickness of the film, and the like.

After the chemical imidization, it is precipitated, dried and dissolved in a solvent to be applied to a support. The applied film is gelled on the support by dry air and heat treatment. The gelation temperature of the coated film is preferably from 100 to 250 ° C, and a glass plate, an aluminum foil, a circulating stainless belt, a stainless steel drum, or the like can be used as a support.

The treatment time required for gelation varies depending on the temperature, the type of the support, the amount of the applied polyamic acid solution, and the mixing conditions of the catalyst, and is not limited to a certain time. Preferably in a range of 5 minutes to 30 minutes.

The gelled film is heat treated away from the support to complete drying and imidization. The heat treatment temperature is in the range of 100 to 500 ° C. and the treatment time is 1 to 30 minutes. The gelled film is fixed to the support at the time of heat treatment and proceeds. The gel film can be fixed using a pin type frame or using a clip type.

The residual volatile component of the film after the heat treatment is 5% or less, preferably 3% or less.

The heat-treated film is heat-treated under a constant tension to remove residual stress inside the film. If the last heat treatment is not performed, the value of the thermal expansion coefficient becomes much smaller than that of the conventional film because a residual stress to shrink in the film reduces thermal expansion. Heat treatment can reduce hysteresis of thermal expansion coefficient. Since the tension and temperature conditions are correlated with each other, the tension condition may vary depending on the temperature. The temperature is preferably maintained between 100 and 500 DEG C, and the time is preferably maintained between 1 minute and 3 hours.

The thickness of the obtained polyimide film is not particularly limited, but is preferably in the range of 10 to 250 탆, more preferably 10 to 100 탆.

The polyimide film produced in the present invention has a coefficient of friction (Static Coefficient) of 0.2 or less, a haze of 2.0% or less, an optical transmittance of 87% or more at a wavelength of 550 nm, and a coefficient of thermal expansion 50 ppm / 占 폚 or less, and a yellowness degree of 5.0 or less based on a film thickness of 80 占 퐉.

The polyimide film of the present invention satisfying the above optical transmittance, yellowing degree, and heat resistance can be used as a protection film or a diffusion film for a TFT-LCD or a coating film which is limited in use due to the yellow of a conventional polyimide film, Interlayer, gate insulator, liquid crystal alignment film, etc., can be used in fields requiring transparency, and TFT-LCD can be manufactured when the above transparent polyimide is applied as a liquid crystal alignment film. It can also be used as a flexible display substrate and a hard coating film to replace glass in conventional displays.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the scope of the present invention is not limited to the following Examples.

≪ Example 1 >

1-1: Preparation of polyimide

       N, N-dimethylacetamide (DMAc) 734.1 g was charged into a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while nitrogen was passed through the reactor, 67.25 g (0.210 mol) of TFDB was dissolved and the solution was kept at 25 캜. 17.73 g (0.040 mol) of 6FDA was added thereto, followed by stirring and stirring for a certain time. The reactor temperature was lowered to 10 ° C, and 142.27 g of N, N-dimethylacetamide (DMAc) and 29.27 g of propylene oxide were added to react. After the temperature of the solution was maintained at 8 ° C, 33.26 g (0.164 mol) of TPC was added and reacted at 25 ° C. for 12 hours to obtain a polyamic acid solution having a solid content of 12 wt% and a viscosity of 250 poise.

13.95 g of pyridine and 18.01 g of acetic anhydride were added to the polyamic acid solution, stirred for 30 minutes, and further stirred at 80 ° C for 1 hour. The mixture was cooled to room temperature and precipitated with 20 L of methanol. The precipitated solid was filtered Thereafter, the resultant was dried in a vacuum at 100 ° C for 6 hours to obtain 103.7 g of a solid content powder of copolymerized polyimide.

Subsequently, 0.03 g of silica (particle size: 0.2 μm) particles were added to 30 g of N, N-dimethylacetamide (DMAc) and subjected to ultrasonic treatment for 1.5 hours to obtain a silica dispersion (dispersion weight: 0.1 wt%). A silica (particle size: 2.7 mu m) dispersion was also prepared in the same manner as described above. 20.0 g of the dispersion of silica (particle size: 0.2 탆) obtained and 10.0 g of silica (particle size: 2.7 탆) dispersion were mixed with 100 g of the polyimide solid content prepared above in a stirrer filled with 703.2 g of N, N-dimethylacetamide (DMAc) , A nitrogen injection apparatus, a dropping funnel, a temperature controller and a condenser, while passing nitrogen through the reactor, and dissolved by stirring.

≪ Particle size measurement method &

Dimethylacetamide (DMAc) as a solvent at 20.0% by weight, and then ultrasonically treated for 1.5 hours. The dispersion thus prepared was injected into a Microtrac S3500 particle size analyzer and the average value was calculated from the measured values .

The particle size of the silica particles described later was measured by the same method as described above.

1-2: Preparation of polyimide film

     The melted mixture was coated on a glass plate, cast and dried for 30 minutes with hot air at 120 DEG C, and then the film was peeled off from the glass plate and pinned to the frame. The film-fixed frame was placed in an oven, heated from 100 ° C to 280 ° C, and then separated from the frame to obtain a polyimide film.

≪ Example 2 >

      40.0 g of the dispersion of silica (particle size: 0.2 탆) and 10.0 g of silica (particle size: 2.7 탆) dispersion were mixed in the same manner as in Example 1 to prepare a polyimide film and a silica dispersion, Was charged into a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen injection device, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Example 3 >

20.0 g of the dispersion of silica (particle size: 0.2 탆) and 15.0 g of silica (particle size: 2.7 탆) dispersion were mixed in the same manner as in Example 1 to prepare a polyimide film and a silica dispersion, Was charged into a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen injection device, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 1 &

1-1: Preparation of polyimide

N, N-dimethylacetamide (DMAc) 734.1 g was charged into a 1 L reactor equipped with a stirrer, a nitrogen injector, a dropping funnel, a temperature controller and a condenser while nitrogen was passed through the reactor, 67.25 g (0.210 mol) of TFDB was dissolved and the solution was kept at 25 캜. 17.73 g (0.040 mol) of 6FDA was added thereto, followed by stirring and stirring for a certain time. The reactor temperature was lowered to 10 ° C, and 142.27 g of N, N-dimethylacetamide (DMAc) and 29.27 g of propylene oxide were added to react. After the temperature of the solution was maintained at 8 ° C, 33.26 g (0.164 mol) of TPC was added and reacted at 25 ° C. for 12 hours to obtain a polyamic acid solution having a solid content of 12 wt% and a viscosity of 250 poise.

13.95 g of pyridine and 18.01 g of acetic anhydride were added to the polyamic acid solution, and the mixture was stirred for 30 minutes and then stirred at 80 ° C for 1 hour. The mixture was cooled to room temperature and precipitated with 20 L of methanol. The precipitated solid was filtered After drying at 100 DEG C under vacuum for 6 hours, a copolymerized polyimide of 102.9 g of a solid powder was obtained.

1-2: Preparation of polyimide film

      100 g of the solid polyimide of Example 1-1 was charged into a 1 L reactor equipped with a stirrer filled with 703.2 g of N, N-dimethylacetamide (DMAc), a nitrogen inlet, a dropping funnel, a temperature controller and a condenser while passing nitrogen And dissolved by stirring.

The dissolved mixture (solid content concentration: 12.54%) was coated on a glass plate, cast and dried for 30 minutes with hot air at 120 ° C, and then the film was peeled off from the glass plate and pinned to the frame. The film-fixed frame was placed in an oven, heated from 100 ° C to 280 ° C, and then separated from the frame to obtain a polyimide film.

≪ Comparative Example 2 &

       A polyimide film was prepared in the same manner as in Example 1 except that 0.03 g of silica (particle size: 0.2 μm) particles were added to 30 g of N, N-dimethylacetamide (DMAc) and ultrasonicated for 1.5 hours to obtain a silica dispersion Weight: 0.1% by weight). 40.0 g of the obtained silica dispersion and 100 g of the polyimide solid were added to a 1 L reactor equipped with a stirrer filled with 703.2 g of N, N-dimethylacetamide (DMAc), a nitrogen inlet, a dropping funnel, a temperature controller and a condenser, , And dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 3 &

A polyimide film was prepared in the same manner as in Example 1 except that 0.03 g of silica (particle size: 0.2 μm) particles were added to 30 g of N, N-dimethylacetamide (DMAc) and ultrasonicated for 1.5 hours to obtain a silica dispersion Weight: 0.1% by weight). 80.0 g of the obtained silica dispersion and 100 g of the polyimide solid were added to a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen inlet, a dropping funnel, a temperature controller and a condenser, , And dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 4 &

A polyimide film was prepared in the same manner as in Example 1 except that 0.03 g of silica (particle size: 1.8 탆) was added to 30 g of N, N-dimethylacetamide (DMAc) and ultrasonicated for 1.5 hours to obtain a silica dispersion Weight: 0.1% by weight). 7.0 g of the obtained silica dispersion and 100 g of the polyimide solid were added to a 1 L reactor equipped with a stirrer, a nitrogen inlet, a dropping funnel, a temperature controller and a condenser filled with 703.2 g of N, N-dimethylacetamide (DMAc) , And dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 5 &

A polyimide film was prepared in the same manner as in Example 1 except that 0.03 g of silica (particle size: 2.7 m) was added to 30 g of N, N-dimethylacetamide (DMAc) and ultrasonicated for 1.5 hours to obtain a silica dispersion Weight: 0.1% by weight). 4.0 g of the obtained silica dispersion and 100 g of the polyimide solid were added to a 1 L reactor equipped with a stirrer, a nitrogen inlet, a dropping funnel, a temperature controller and a condenser filled with 703.2 g of N, N-dimethylacetamide (DMAc) , And dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 6 >

A polyimide film was prepared in the same manner as in Example 1 except that 0.03 g of silica (particle size: 2.7 m) was added to 30 g of N, N-dimethylacetamide (DMAc) and ultrasonicated for 1.5 hours to obtain a silica dispersion Weight: 0.1% by weight). To a 1 L reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a condenser filled with 703.2 g of N, N-dimethylacetamide (DMAc), 9.0 g of the obtained silica dispersion and 100 g of the solid polyimide prepared above, , And dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 7 &

A polyimide film was prepared in the same manner as in Example 1 except that 0.03 g of silica (particle size: 2.7 m) was added to 30 g of N, N-dimethylacetamide (DMAc) and ultrasonicated for 1.5 hours to obtain a silica dispersion Weight: 0.1% by weight). 130.0 g of the silica dispersion thus obtained and 100 g of the polyimide solid were added to a 1 L reactor equipped with a stirrer, a nitrogen inlet, a dropping funnel, a temperature controller and a condenser filled with 703.2 g of N, N-dimethylacetamide (DMAc) , And dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 8 >

10.0 g of the dispersion of silica (particle size: 0.2 탆) and 7.0 g of the dispersion of silica (particle size: 1.8 탆) were mixed in the same manner as in Example 1 to prepare a polyimide film and a silica dispersion, Was charged into a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen injection device, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 9 &

50.0 g of the dispersion of silica (particle size: 0.01 탆) and 10.0 g of silica (particle size: 2.0 탆) dispersion were mixed in the same manner as in Example 1 to prepare a polyimide film and a silica dispersion. Was charged into a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen injection device, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 10 &

10.0 g of the dispersion of silica (particle size: 0.4 탆) and 10.0 g of the dispersion of silica (particle size: 6.0 탆) were mixed in the same manner as in Example 1 to prepare a polyimide film and a silica dispersion. Was charged into a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen injection device, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 11 &

10.0 g of the dispersion of silica (particle size: 0.4 탆) and 10.0 g of silica (particle size: 2.0 탆) dispersion were mixed in the same manner as in Example 1 to prepare a polyimide film and a silica dispersion, Was charged into a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen injection device, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

≪ Comparative Example 12 >

A polyimide film and a silica dispersion were prepared in the same manner as in Example 1, except that 50.0 g of the dispersion of silica (particle size: 0.01 m) and 10.0 g of silica (particle size: 6.0 m) dispersion were mixed with 100 g Was charged into a 1 L reactor equipped with a stirrer filled with N, N-dimethylacetamide (DMAc), a nitrogen injection device, a dropping funnel, a temperature controller and a condenser while passing nitrogen, and dissolved by stirring. Then, a polyimide film was obtained in the same manner as in Example 1 above.

(1) Optical transmittance

The films prepared in Examples and Comparative Examples were measured for optical transmittance at 550 nm using a UV spectrometer (Kotikaminolta CM-3700d).

(2) Yellow Index (Y.I.)

The yellowing degree was measured according to the ASTM E313 standard using a UV spectrometer (Kotikaminolta CM-3700d).

(3) Measurement of friction coefficient

The LLOYD FT1 Friction Tester was used to measure the coefficient of friction of the film, and the Sled weight was measured at a moving speed of 100.0 mm at a speed of 250.0 mm / min, an area of 63.0 × 68.0 mm, and a weight of 280 gf. At this time, the material of the sled face and the base face were arranged in the same film.

(4) Haze measurement

Haze Meter HM-150 was used to measure film haze.

(5) Thickness measurement

The thickness was measured with an Anritsu Electronic Micrometer and the deviation of the device was less than ± 0.5%.

(6) Difference measurement

The LLOYD FT1 Friction Tester was used to measure the coefficient of friction of the film, and the Sled weight was measured at a moving speed of 100.0 mm at a speed of 250.0 mm / min, an area of 63.0 × 68.0 mm, and a weight of 280 gf. At this time, the material of the sled face and the base face were arranged in the same film. Here, the difference between the static friction coefficient and the dynamic friction coefficient is defined as a difference.

Silica type (particle size: 탆) Dispersion Input (g) Thickness (㎛) Optical Transmittance (%) Yellowing degree
(YI) Haze
(%) Static
Coefficient Diff.
(Static-Kinetic) Comparative Example 1 - - 80 88.0 4.58 0.3 1.82 0.75 Comparative Example 2 0.2 40 80 88.1 4.64 0.9 1.57 0.64 Comparative Example 3 0.2 80 80 87.9 4.54 1.4 1.42 0.56 Comparative Example 4 1.8 7 80 88.7 4.24 1.6 1.26 0.95 Comparative Example 5 2.7 4 80 88.5 4.35 0.5 1.12 0.82 Comparative Example 6 2.7 9 80 88.2 4.44 1.0 0.39 0.26 Comparative Example 7 2.7 130 80 87.9 4.58 11.2 0.11 0.06 Comparative Example 8 0.2 / 1.8 10/7 80 88.5 4.58 2.1 0.74 0.56 Comparative Example 9 0.01 / 2.0 50/10 80 88.2 4.42 2.9 0.95 0.45 Comparative Example 10 0.4 / 6 10/10 80 87.9 4.62 2.8 0.26 0.12 Comparative Example 11 0.4 / 2.0 10/10 80 88.1 4.75 3.4 1.12 0.62 Comparative Example 12 0.01 / 6 50/10 80 87.8 4.53 2.5 0.42 0.26 Example 1 0.2 / 2.7 20/10 80 87.9 4.27 1.6 0.08 0.00 Example 2 0.2 / 2.7 40/10 80 87.9 4.52 1.8 0.08 0.00 Example 3 0.2 / 2.7 20/15 80 87.9 4.38 1.96 0.06 0.00

As a result of the physical property evaluation, it can be seen that the friction coefficient varies depending on the size and content of the silica particles. However, the haze characteristics were lowered compared with the polyimide film (Comparative Example 1) produced without using the silica particles.

In Comparative Examples 2 to 5, since the silica particle size is small, the optical properties are more than a certain level, but the friction coefficient is remarkably poor. In Comparative Examples 7 to 8, the silica content is high, However, it was found that the haze was not very good and the optical characteristics were not all satisfied.

In Comparative Example 6, surface protrusions were formed by introducing silica particles of a relatively large size, and the optical characteristics were satisfied at a certain level, and the friction coefficient was remarkably improved as compared with Comparative Examples 2 to 5 and 7 to 8. However, To 3, the coefficient of friction was lowered.

Also, the difference among the physical properties represents a difference value between the static friction coefficient and the dynamic friction coefficient.

The coefficient of static friction is generally equal to or greater than the coefficient of dynamic friction, and the characteristic value increases when the surface adhesion is high. In Examples 1 to 3, film adhesion hardly occurs, so that the difference between the static friction coefficient and the dynamic friction coefficient, that is, the difference is 0.0. In Comparative Examples 1 to 5, the difference between the static friction coefficient and the dynamic friction coefficient is large, There was a growing problem.

As a result, the haze characteristics deteriorate as the friction characteristics are improved. However, in Examples 1 to 3 including the first silica particles and the second silica particles each having the particle size according to the present invention, the optical characteristics were satisfied, The results of this study are as follows.

Claims (9)

A copolymerized polyimide resin including a dianhydride, an aromatic dicarbonyl compound, and a diamine;
A first silica having a particle size of 0.05 to 0.3 탆 and a second silica having a particle size of 2.3 to 5 탆.
The method according to claim 1, wherein the content of the first silica particles is 0.01 to 0.05 parts by weight based on 100 parts by weight of the polyimide resin, and the content of the second silica particles is 0.008 to 0.016 parts by weight based on 100 parts by weight of the polyimide resin Wherein the polyimide resin composition is a polyimide resin composition.
The method of claim 1, wherein the dianhydride is selected from the group consisting of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropanediamine hydrate (6FDA), biphenyltetracarboxylic dianhydride (BPDA), 4 - (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellitic acid dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (BTDA), oxydiphthalic dianhydride (ODPA), biscarboxyphenyldimethylsilanediamine hydride (SiDA), bisdicarboxyphenoxy diphenylsulfide dianhydride BDSDA), sulfonyldiphthalic anhydride (SO ₂ DPA), isopropylidene is at least one selected from the group consisting of phenoxy bisphthalic anhydride (6HBDA), and a group of the above polyimide resin compositions.
The method of claim 1, wherein the diamine is selected from the group consisting of oxadiazines (ODA), p-phenylenediamine (pPDA), m-phenylenediamine (mPDA), p- methylenediamine (pMDA) , Bisaminophenoxybenzene (133APB), bisaminophenoxybenzene (134APB), bisaminophenoxyphenylhexafluoropropane (4BDAF), bisaminophenylhexafluoropropane (33-6F), bisaminophenylhexafluoro (14CHD), cyclohexanediamine (14CHD), bisaminophenoxine (14CHD), bis-aminophenylsulfone (4DDS), bis-aminophenylsulfone (3DDS), bistrifluoromethylbenzidine (4-aminophenyl) fluorene (FDA), bis (4-aminophenyl) fluorene, bis (aminophenyl) 3-fluorophenyl) fluorene (F-FDA) and one or more of these groups Polyimide resin composition as.
The aromatic dicarbonyl compound according to claim 1, wherein the aromatic dicarbonyl compound is selected from the group consisting of terephthaloyl chloride (TPC), terephthalic acid (TPA), isophthaloyl dichloride (IPC), 4,4'-benzoyl chloride (BZC) Wherein the polyimide resin composition is a polyimide resin composition.
A polyimide film produced from the polyimide resin composition according to any one of claims 1 to 5.
The polyimide film according to claim 6, wherein the film has a coefficient of friction (Static Coefficient) of 0.2 or less.
The method according to claim 6,
The polyimide film has a haze of not more than 2.0, an optical transmittance of not less than 87% at a wavelength of 550 nm, a coefficient of thermal expansion (CTE) of 50 ppm / ° C or less at 50 to 250 ° C and a yellowness Lt; RTI ID = 0.0 > 5. ≪ / RTI >
A substrate for a display element comprising the polyimide film according to claim 6.