WO2017116103A1 - Polyimide substrate and display substrate module comprising same - Google Patents

Abstract

The present invention relates to a polyimide substrate comprising a polyimide layer and an optical primer layer below the polyimide layer, and a display substrate module comprising the same, wherein the optical primer layer comprises a silazane-siloxane resin compound, a norbonene resin compound and an acrylic compound.

Description

Polyimide substrate and display substrate module comprising the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyimide substrate and a display substrate module including the same, and more particularly, to a polyimide substrate useful as a cover substrate of a flexible electronic device having excellent bending characteristics and impact resistance, and a display substrate module including the same. .

Recently, as an electronic device that can bend or bend as one of the next generation displays, flexible electronic devices such as flexible OLED, light weight display, flexible encapsulant, color EPD, plastic LCD, TSP, OPV, etc. have. Such a flexible display that can bend or bend is possible, and a new type of flexible cover substrate is required to replace the existing glass cover substrate to protect the lower element. In addition, such a substrate needs to maintain high hardness, low moisture permeability, chemical resistance, and light transmittance in order to protect components included in the display device.

As a flexible display cover substrate material, various high hardness plastic substrates are considered as candidates, and among them, transparent polyimide films capable of high hardness and thinness are considered as major candidates. However, since the transparent plastic substrate has a lower surface hardness than glass, there is a limit in securing wear resistance. For this purpose, high hardness coating, that is, hard coating technology, for improving the surface hardness of the polymer film has become an important issue.

In order to improve the surface hardness of a plastic substrate, Korean Patent Laid-Open Publication No. 2010-0041992 provides a high hardness hard coat film composition comprising an ultraviolet curable polyurethane acrylate oligomer, and WO2013-187699. The high hardness siloxane resin composition containing an alicyclic epoxy group, its manufacturing method, and the optical film containing the said hardened | cured material are proposed.

As such, the film to be reviewed as a flexible electronic device cover substrate material has a method of directly forming an acrylic or epoxy-based organic cured film on the surface of the transparent film in order to improve the hardness, but has a hard coating layer having a large difference in strength from that of the plastic substrate. In the case of forming directly on the plastic substrate, not only the flexibility of the plastic substrate is impaired, but also the coating layer is not flexible and the surface is cracked when the bending property or impact resistance is evaluated.

Accordingly, the optical properties and moisture barrier properties are improved while maintaining the warpage characteristics and surface hardness compared to the substrate in which the hard coating layer is directly formed on the polyimide film through the present invention, and the optical primer layer is oriented in a predetermined direction, thereby requiring a polarizing plate layer. It is intended to provide a polyimide substrate that is free.

The first preferred embodiment of the present invention for solving the above problems is a polyimide layer; And a silazane-siloxane resin compound comprising a repeating unit represented by the following Chemical Formula 1-1 and a repeating unit represented by the following Chemical Formula 1-2 on at least one surface of the polyimide layer, and a repeating unit represented by the following Chemical Formula 2 It is to provide a polyimide substrate comprising an optical primer layer containing a norbornene resin compound.

<Formula 1-1>

<Formula 1-2>

In Formulas 1-1 and 1-2, R ₁ is a urethane group, R ₂ is a cyanate group, R ₃ is selected from the group consisting of a hydroxyl group, a vinyl group, an acryl group, an epoxy group and an amine group, m and n is an integer from 1 to 10.

<Formula 2>

The silazane-siloxane resin is characterized in that the weight average molecular weight of 500 to 500,000 g / mol.

The norbornene resin compound is characterized in that the weight average molecular weight of 500 to 150,000g / mol.

The silazane-siloxane resin to the norbornene resin compound may be included in a weight ratio of 1: 0.1 to 1.0.

The optical primer layer is characterized in that it contains an acrylic compound.

The acrylic compound may be included in an amount of 10 to 200 parts by weight based on 100 parts by weight of the norbornene resin compound.

The acryl-based compound may be a trifunctional acrylate monomer, dipentaerytritol triacrylate (PETA), a bifunctional acrylate monomer hexanediol diacrylate (HDDA) and a 6 functional acrylate monomer. It is characterized in that at least one selected from the group consisting of DIPENTAERYTHRITOL HEXAACRYLATE (DPEHA).

The optical primer layer is characterized in that the thickness of 0.1 to 3 ㎛.

The optical primer layer may include a silazane-siloxane resin compound including a repeating unit represented by Formula 1-1 and a repeating unit represented by Formula 1-2, and a norbornene resin including a repeating unit represented by Formula 2 Forming a film with an optical primer resin solution containing a compound, characterized in that it is produced, including the step of heat treatment at a temperature of 200 to 300 ℃.

The polyimide substrate is characterized in that the yellowness of 2.5 or less, based on the KONICA MINOLTA company CM-3700D measurement, the light transmittance at 550nm is 85 to 93%.

The polyimide substrate may further include a hard coating layer.

The hard coating layer is formed from a siloxane resin comprising a mixture or a chemical reactant of the alkoxy silane represented by the following formula (3) and the alkoxy metal represented by the following formula (4).

<Formula 3>

<Formula 4>

In Formulas 3 to 4, R ¹ is a linear, branched, alicyclic, aromatic organic compound including epoxy, acryl, and isocyanate, and R ² and R ³ are linear, including a hetero compound such as oxygen or nitrogen, branched, an alkyl group of alicyclic C ₁ to C _8, n is an integer from 1 to 3. In addition, M is a metal element including a transition metal, and m is an integer of 1-10.

The hard coating layer is characterized in that the thickness of 10 to 50㎛.

The polyimide substrate is characterized in that JIS K56000 reference surface hardness is 5H to 9H.

The polyimide substrate is characterized in that the ASTM E96BW measurement moisture permeability of 0.001 to 10g / m ² * day.

In addition, another preferred embodiment of the present invention is to provide a display substrate module comprising a transparent adhesive layer, a black mattress layer and the above-described polyimide substrate.

According to the present invention, it is possible to provide a transparent polyimide substrate having excellent bending characteristics and impact resistance, and having solvent resistance, optical characteristics, moisture barrier properties, and scratch resistance. The transparent polyimide substrate according to the present invention can be usefully used as a cover substrate of a flexible electronic device, thereby providing a flexible display substrate module having excellent bending characteristics and impact resistance.

In addition, the optical primer layer included in the polyimide substrate according to the present invention has an optical functional group, and by adding UV polarization irradiation in the manufacturing process of the optical primer layer, the surface of the coated optical primer layer can be oriented in a predetermined direction. Thus, the refractive index and the light transmittance have polarization, and thus, when applied to the display element, it is possible to provide an improvement in visibility.

1 is a cross-sectional view illustrating a structure of a display substrate module including a polyimide substrate according to an embodiment of the present invention.

According to an aspect of the present invention, a polyimide layer; And a silazane-siloxane resin compound comprising a repeating unit represented by the following Formula 1-1 and a repeating unit represented by the following Formula 1-2 on at least one side of the polyimide layer, and a repeating unit represented by the following Formula 2 It is possible to provide a polyimide substrate comprising an optical primer layer containing a norbornene resin compound.

<Formula 1-1>

<Formula 1-2>

In Formulas 1-1 and 1-2, R ₁ is a urethane group, R ₂ is a cyanate group, R ₃ is selected from the group consisting of a hydroxyl group, a vinyl group, an acryl group, an epoxy group and an amine group, m and n is an integer from 1 to 10.

<Formula 2>

In the present invention, the polyimide layer is made of a polyimide film, wherein the polyimide film can be obtained by polymerizing diamine and acid dianhydride and then imidizing. The polyimide layer of the present invention can be applied without limitation as long as it is a colorless and transparent polyamide film having a unique heat resistance of the polyimide-based resin and does not have a yellow color, and is based on a UV spectrophotometer based on a film thickness of 10 to 100 μm. It is a polyimide film with an average transmittance of at least 85%, a yellowness of 5 or less, and an average coefficient of linear expansion (CTE) measured at 50 to 250 ° C. according to TMA-Method of 50.0 ppm / ° C. or less according to TMA-Method. It is more preferable.

The transmittance is preferably higher than 85%, it may have a transmittance of 89%, 90%, 91%.

The yellowness is preferably lower than 5, and may have yellowness of 2.0, 1.9, or 1.5.

The average linear expansion coefficient (CTE) is preferably lower than 50.0 ppm / ° C., and may have an average linear expansion coefficient (CTE) of 2.0 ppm / ° C. or less.

The above-described physical properties such as transmittance, yellowness, average linear expansion coefficient (CTE), etc. are measured when the thickness of the film is in the range of 10 to 100 μm, for example, 11 μm, 12 μm, 13 μm,. It can be measured as a film having a thickness of 100㎛, etc., when measuring the film in each of the thickness can satisfy all of the physical properties range. At this time, the thickness range of the film corresponds to the measuring method for measuring the physical properties, and unless otherwise specified, does not mean limiting the thickness of the film.

If the polyimide film thickness is 10 to 100 µm, the average transmittance is less than 85%, or if the yellowness is greater than 5, there is a problem that the transparency is not applicable to a display or an optical element, and the average linear expansion coefficient is If the (CTE) exceeds 50.0 ppm / ° C, the difference in thermal expansion coefficient with the plastic substrate becomes large, and there is a possibility that a short circuit occurs when the device is overheated or has a high temperature.

In the present invention, the silazane-siloxane resin compound includes a repeating unit represented by the following Formula 1-1 and a repeating unit represented by the following Formula 1-2, and the weight average molecular weight measured by GPC (gel permeation chromatography) It is preferred that it is 500 to 500,000 g / mol.

<Formula 1-1>

<Formula 1-2>

In Formulas 1-1 and 1-2, R ₁ is a urethane group, R ₂ is a cyanate group, R ₃ is selected from the group consisting of a hydroxyl group, a vinyl group, an acryl group, an epoxy group and an amine group, m and n is an integer from 1 to 10.

When the weight average molecular weight of the silazane-siloxane compound is less than 500 g / mol, the effect of improving solvent resistance, heat resistance, and water barrier property is insignificant, and when it exceeds 50,000 g / mol, the hydrophobic property is improved to bond with other compounds. You may lack sex. Since the silazane-siloxane compound has a high density structure, it serves to improve the chemical resistance of the substrate, and shows a low refractive index compared to the substrate, thereby improving the optical properties of the polyimide film due to reinforcement interference with the substrate layer. It can improve more.

The silazane-siloxane compound to the norbornene resin compound is preferably included in a weight ratio of 1: 0.1 to 1.0 in that the object and effect of the present invention can be obtained.

The norbornene resin compound is a compound having a cinnamate group. When UV is irradiated, the norbornene resin compound crosslinks in one direction without a heat source to have an orientation of the film, and has a low temperature process.

In the present invention, the norbornene resin compound may be introduced by mixing with a primer to obtain an orientation (polarization) effect.

The norbornene resin compound preferably has a weight average molecular weight of 500 to 150,000 g / mol.

The optical primer layer according to the present invention may further include an acrylic compound.

The acrylic compound may be included in an amount of 10 to 200 parts by weight, preferably 50 to 100 parts by weight, and more preferably 60 to 100 parts by weight, based on 100 parts by weight of the norbornene resin compound. It is preferable in that it can obtain, and improves the adhesive force between the optical primer layer and the hard coating layer, and also improves the bending crack required in the flexible substrate.

The acryl-based compound may be a trifunctional acrylate monomer, dipentaerytritol triacrylate (PETA), a bifunctional acrylate monomer hexanediol diacrylate (HDDA) and a 6 functional acrylate monomer. At least one selected from the group consisting of DIPENTAERYTHRITOL HEXAACRYLATE (DPEHA).

The silazane-siloxane resin is applied by dissolving in an organic solvent, wherein the applicable organic solvent is isopropyl alcohol (IPA), propylene glycol monomethyl ether (PGME), propylene glycol monomethyl ether acetate (PGMEA) , N-Butanol, Pentanol, methyl ethyl ketone (MEK), Acetone, Methyl alchol, Ethyl alchol, but is not limited to these. The suitable organic solvent amount of this compound is 0.5 to 90% of the total weight of the primer resin, and if it is less than 0.5%, it may not be uniformly formed during application, which may cause thickness deviation on the surface of the substrate. It is difficult to apply to a substrate.

In addition, in the present invention, the optical primer layer including the silazane-siloxane resin compound preferably has a thickness of 0.1 μm or more in order to secure solvent resistance and optical properties and improve moisture blocking properties, and the optical properties of the polyimide cover substrate. In order to prevent a fall and the generation of curl, it is preferable to make thickness into 3 micrometers or less. The optical primer layer may be formed on one side of the polyimide film, but may also be formed on both sides, and the polyimide substrate including the optical primer layer according to the present invention is based on CM-3700D measurement, yellowness of 2.5 Hereinafter, the optical transmittance at preferably 2.0 or less and 350 to 700 nm can exhibit excellent optical properties of 85 to 93%, preferably 91 to 93%.

The optical primer layer may include a silazane-siloxane resin compound including a repeating unit represented by Formula 1-1 and a repeating unit represented by Formula 1-2, and a norbornene resin including a repeating unit represented by Formula 2 After forming a film with an optical primer resin solution containing a compound, it may be prepared including a step of heat treatment at a temperature of 200 to 300 ℃.

In the present invention, the optical primer layer may be coated with the optical primer resin solution on a substrate and then dried to form a film. The coating method may include spray coating, bar coating, and spin. Various methods such as coating and dip coating may be selected and coated, and the coating method and the drying method may be applied without being limited thereto as long as they are generally applied.

The optical primer layer is advantageously heat treated at a temperature of 200 to 300 ° C. to have an intramolecular network structure, which makes the film property more rigid, thereby making it excellent in chemical resistance and heat resistance.

In addition, the UV polarization irradiation step after the heat treatment process may be further performed, it is possible to orient the surface of the optical primer layer in a predetermined direction by the UV polarization irradiation process.

According to a preferred embodiment of the present invention, the polyimide substrate further comprises a hard coating layer, thereby securing chemical resistance and impact resistance, and can exhibit a surface hardness of JIS K56000 measurement standards 5H to 10H. Above all, the hard coating layer is formed on the optical primer layer, so that the optical coating such as transmittance and yellowness is maintained while the hard coating is laminated directly on the polyimide film, while the ASTM E96BW measurement moisture permeability is 0.001 to 10 g. / m ² * day, preferably from 0.001 to 3.1 g / m ² * day. In particular, the polyimide substrate of the present invention exhibits low moisture permeability in the above range, which may be advantageous for protecting TFT and OLED devices from external humid environments.

At this time, according to a more preferred embodiment of the present invention, the hard coating layer may be formed from a siloxane resin containing a mixture or a chemical reactant of the alkoxy silane represented by the following formula (3) and the alkoxy metal represented by the following formula (4).

<Formula 3>

<Formula 4>

In Formulas 3 to 4, R ¹ is a linear, branched, alicyclic, aromatic organic compound including epoxy, acryl, and isocyanate, and R ² and R ³ are linear, including a hetero compound such as oxygen or nitrogen, branched, an alkyl group of alicyclic C ₁ to C _8, n is an integer from 1 to 3. In addition, M is a metal element including a transition metal, and m is an integer of 1-10.

In the present invention, the siloxane resin may be prepared from a polymerization reaction of the alkoxy silane of Formula 3 alone, or may be prepared as a siloxane resin in which a chemical bond of a metal element exists by introducing an alkoxy metal of Formula 3 during the polymerization reaction. have. The formation reaction of the siloxane resin may proceed at room temperature, but may be stirred for 1 hour to 120 hours at 50 ℃ to 120 ℃ to promote the reaction.

In addition, as a catalyst for the hydrolysis and condensation reaction during the reaction, an acid catalyst such as hydrochloric acid, acetic acid, hydrogen fluoride, nitric acid and iodide sulfate, base such as ammonia, potassium hydroxide, sodium hydroxide, barium hydroxide, imidazole and the like Catalysts and ion exchange resins such as Amberite may be used, and these catalysts may be used alone but may be used in combination. The amount of the catalyst is not particularly limited, but may be added in an amount of 0.0001 to about 10 parts by weight based on 100 parts by weight of the siloxane resin.

When the hydrolysis and condensation reaction proceeds, by-product alcohol is generated, and by removing this, the reverse reaction can be reduced to allow the forward reaction to proceed more quickly, and the reaction rate can be controlled through the reaction. In addition, after the reaction, the by-products can be removed by applying heat under reduced pressure.

As described above, the siloxane resin synthesized by the condensation reaction may adjust the viscosity and the curing rate by the monomers added during the reaction, thereby providing an optimum resin composition suitable for the purpose. In addition, the siloxane resin obtained through the reaction as described above can secure the intermolecular space during crosslinking, thereby preventing the curl phenomenon caused by curing shrinkage, and enables high surface hardness by crosslinking and metal elements.

Meanwhile, according to a preferred embodiment of the present invention, the hard coating resin composition may further include an initiator for polymerization of the siloxane resin, for example, a photopolymerization initiator such as an organometallic salt and a thermal polymerization initiator such as amine or imidazole. Can be used. At this time, the addition amount of the initiator is not particularly limited, but may be added from about 0.01 to 10 parts by weight based on about 100 parts by weight of the siloxane resin.

In addition, the hard coating resin composition of the present invention may further add an organic solvent to control the viscosity of the siloxane resin to facilitate the processability and at the same time adjust the thickness of the coating film. The addition amount of the organic solvent is not particularly limited, but examples of the organic solvent that can be used include ketones such as acetone, methyl ethyl ketone, methyl butyl ketone and cyclohexanone, or cellosolves such as methyl cellosolve and butyl cellosolve, Or ethers such as ethyl ether and dioxane, alcohols such as isobutyl alcohol, isopropyl alcohol, butanol and methanol, or halogenated hydrocarbons such as dichloromethane, chloroform and trichloroethylene, or normal hexane, benzene and toluene It may include one or more selected from a solvent consisting of hydrocarbons and the like.

In one embodiment of the present invention, the siloxane resin may further include an antioxidant to suppress the oxidation reaction resulting from the polymerization reaction, and may further include a leveling agent or a coating aid, but is not necessarily limited thereto. no.

The resin composition for hard coating of the present invention may be prepared into a hardened coating cured product by photopolymerization and thermal polymerization after molding such as coating, casting, and molding. For the photopolymerization it is possible to obtain a uniform surface over the light article pre-heat treatment, which can be carried out at a temperature below about 300 ℃ than 40 ℃, if the irradiation light amount performed under the conditions of 50mJ / cm ² or more 20000mJ / cm ² or less It may be, but is not limited thereto. In addition, the thermal polymerization may be performed at a temperature of about 40 ° C. or more and about 300 ° C. or less, but is not limited thereto.

In the present invention, the hard coating layer formed as described above preferably has a dry thickness of 10 μm or more for ensuring excellent surface hardness, impact resistance, and chemical resistance, and is preferably formed to be less than 50 μm to prevent warpage and excessive stiffness. .

Furthermore, the present invention can provide a display substrate module including a transparent adhesive layer , a black mattress, and a polyimide substrate having the aforementioned characteristics. Although not limited thereto, the display substrate module of the present invention is, for example, the optical primer layer 20, the polyimide layer 10, the optical primer layer 20 and the hard coating layer 30 sequentially as shown in FIG. It may be prepared by forming a transparent adhesive layer 40 and the black mattress 50 in the direction of the lower optical primer layer on the laminated polyimide substrate.

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are only for illustrating the present invention more specifically, and the present invention is not limited thereto.

Production Example 1. Manufacture of Polyimide Film

1-1: Polyimide Powder Manufacturing

After filling 832 g of N, N-dimethylacetaamide (DMAc) while passing nitrogen through a 1L reactor equipped with a stirrer, a nitrogen injection device, a dropping funnel, a temperature controller and a cooler as a reactor, the temperature of the reactor was adjusted to 25 ° C. 6.6046 g (0.2 mol) of bis trifluoromethyl benzidine (TFDB) was dissolved to maintain this solution at 25 ° C. Here, 31.09 g (0.07 mol) of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and 8.83 g (0.03 mol) of biphenyl tetracarboxylic dianhydride (BPDA) ) Was added and stirred for a certain time to dissolve and react. At this time, the temperature of the solution was maintained at 25 ℃. And 20.302 g (0.1 mol) of terephthaloyl chloride (TPC) was added to obtain a polyamic acid solution having a solid content of 13% by weight.

25.6 g of pyridine and 33.1 g of acetic anhydride were added to the polyamic acid solution, followed by stirring for 30 minutes, and then stirred at 70 ° C. for 1 hour to cool to room temperature, which was precipitated with 20 L of methanol, and the precipitated solid was filtered and ground. After drying for 6 hours in a vacuum at 100 ℃ to obtain a polyimide of 111g of solid powder.

1-2: polyimide film production

0.03 g (0.03 wt%) of amorphous silica particles having OH groups bound to the surface were added to N, N-dimethylacetamide (DMAc) at a dispersion concentration of 0.1%, and subjected to sonication until the solvent became transparent. 100 g of the obtained polyimide of the solid powder was taken and dissolved in 670 g of N, N-dimethylacetaamide (DMAc) to obtain a 13 wt% solution. The solution thus obtained was applied to a stainless plate, cast at 340 μm, dried for 30 minutes with hot air at 130 ° C., and the film was peeled off from the stainless plate to be fixed to the frame with a pin.

The film on which the film was fixed was placed in a vacuum oven and slowly heated for 2 hours from 100 ° C to 300 ° C, and then slowly cooled to separate from the frame to obtain a polyimide film. After the final heat treatment was performed for 30 minutes at 300 ℃ again. The polyimide film thus prepared had a thickness of 80 μm, an average light transmittance of 87%, a yellowness of 4.5, and an average linear expansion coefficient (CTE) measured at 50 to 250 ° C. according to TMA-Method. .

Preparation Example 2 Preparation of Hard Coating Composition

KBM-303 (Shinetsu Co., Ltd.), Titanium isopropoxide (Sigma-Aldrich Co., Ltd.) and H ₂ O were mixed in a ratio of 227.96 mL: 1.94 mL: 21.61 mL in a 500 mL flask, and 0.2 g of sodium hydroxide was added as a catalyst. Stir at rt for 24 h. Thereafter, the resultant was filtered using a 0.45 um Teflon filter to obtain a siloxane resin having a number average molecular weight of 7245, a weight average bacterium molecular weight of 20146, and a polydispersity index (PDI, M _w / M _n ) of 2.78 (the molecular weight using GPC). Measure). Here, IRGACURE 250 (BASF, Inc.) was added as a photoinitiator 3 parts by weight based on 100 parts by weight of the resin to finally obtain a composition for hard coating.

Example 1

A silazane-siloxane resin compound having a weight average molecular weight of 2,000 g / mol (DCT) and a norbornene resin compound having a cinnamate group having a weight average molecular weight of 150,000 g / mol are added at a weight ratio of 1: 0.6, and an acrylic compound ( Hi CNP model name HIK-2000) Was added to cyclohexanone in an amount of 60 parts by weight based on 100 parts by weight of the norbornene resin compound having the cinnamate group, and then dissolved to prepare an optical primer resin solution.

The prepared optical primer resin solution was applied to one surface of the colorless and transparent polyimide film prepared through the preparation example, and then dried at a temperature of 80 ° C. to form a film having a thickness of 0.1 μm. Thereafter, the mixture was left to stand at room temperature for about 5 minutes and then heat-treated at a temperature of about 250 ° C., followed by irradiation with UV linearly polarized ultraviolet rays (300 mW / cm 2) to orientate the photo alignment layer. At this time, the polarization direction of the linearly polarized ultraviolet light was controlled by a method of irradiating UV polarization by placing a lattice-type pattern mask on the path of the film so as to form an angle of 60 ° or more with the boundary line of the film.

After the alignment treatment, an optical primer layer having a thickness of 0.1 μm was formed to prepare a polyimide substrate.

Example 2

A polyimide substrate having an optical primer layer was prepared in the same manner as in Example 1, except that the siloxane resin of Preparation Example 2 was coated with 40 μm on the back of the optical primer layer, and then exposed to an ultraviolet lamp having a wavelength of 315 nm for 30 seconds. By further forming a hard coating layer.

Comparative Example 1

The polyimide film produced in Preparation Example 1 was prepared as it was as Comparative Example 1.

Comparative Example 2

In the polyimide film of Preparation Example 1, the optical primer layer was omitted, and only the hard coating layer was formed in the same manner as in Example 2 to prepare a polyimide substrate.

Measurement Example

The physical properties were measured by the following method, and the results are shown in Table 1 and Table 2.

(1) Average light transmittance (%): The optical transmittance at 350-700 nm was measured using the spectrophotometer (CM-3700D, KONICA MINOLTA) by the standard specification ASTM E313.

(2) Yellowness: Yellowness was measured by using a spectrophotometer (CM-3700D, KONICA MINOLTA) as a standard standard ASTM E313.

(3) Moisture Permeability (g / m ² * day): The moisture permeability (WVTR) was measured using a moisture permeability tester (MOCON / US / Aquatran-model-1) using the standard standard ASTM E69BW.

(4) Pencil hardness: 50mm at a speed of 180mm / min with a load of 1kg (in the direction of the coating layer, if a coating layer is formed) using an electric pencil hardness tester with Mitsubishi evaluation pencil (UNI) according to the standard specification ASTM D3363 After drawing five times, the pencil hardness without any scratches on the surface was measured.

(5) Adhesiveness (Removability after Cross Cut with tape): Measured by Taping after Cross Cut with standard specification (ASTM D3359).

(6) Bending characteristics: wound the substrate in the center of a circular tool with a diameter of 2mm and repeated 200,000 times by visually and observing the film for cracking. If any cracking occurs, mark it as 'Failed'. 'OK'.

 (7) Contrast: After displaying white and black images on an image display device using PR-705 (Photo Research) in a room temperature dark room, the front direction of the screen (polar angle 0 ') and the tilt direction (azimuth angle 45 to 60 ') Yrkatdmf of the XYZ display system was measured, the contrast ratio “YW / YB” in the oblique direction was calculated from the Y value (YW) of the white image and the Y value (YB) of the black image. The better the polarization efficiency of the films prepared above, the higher the contrast ratio.

(8) thermal expansion coefficient (CTE) measurement

The TMA (TA Instrument, Inc., Q400) was used to measure the linear thermal expansion coefficient at 50 to 250 ° C. twice according to the TMA-Method. The size of the specimen was 4 mm × 24 mm, the load was 0.02 N, and the temperature increase rate was 10 ° C./min.

 After the film was formed and residual stress could remain in the film through heat treatment, the first run was completely removed and the second value was presented as a real measurement.

division	Permeability (%)	Yellow road	Moisture permeability (g / m 2 / day)	Pencil hardness	Adhesive	Flexural characteristics	Contrast ratio in the front direction (polar angle 0 ')	Contrast ratio in the inclined direction (polar angle 60 / azimuth angle 45 '”)
Example 1	91	2.0	> 50	2H	5B	OK	587.6	29.4
Example 2	91	2.0	3.1	9H	5B	OK	589.7	29.9
Comparative Example 1	89	4.5	> 50	2H	5B	OK	476	26.2
Comparative Example 2	88	4.4	17.0	9H	5B	OK	413.0	14.6

As can be seen from the results of Table 1, in the case of Examples 1 to 2 in which the optical primer layer was formed on the surface of the polyimide film, light transmittance, yellowness, etc. were improved compared to Comparative Example 1, which did not have any treatment on the surface. It was found. In addition, in the case of Comparative Example 2 subjected to the hard coating treatment, the chemical resistance and the pencil hardness were excellent, but the optical properties were poor due to the low yellowness and the transmittance, whereas the optical primer layer was formed before the hard coating layer was formed as in Example 2. In one case, the chemical resistance was complemented, and above all, the optical properties and the moisture permeability were confirmed to be improved compared to Comparative Example 2. In addition, it can be seen that the contrast ratio in the front is higher than that of the base film and the primer film due to the polarization function included in the optical primer layer. The higher the contrast ratio, the higher the sharpness of the screen (image), thereby improving visibility.

Through these results, the polyimide substrate according to the present invention realizes excellent optical properties as well as surface hardness, chemical resistance, and bending characteristics and high coat last, and is suitable as a display substrate module for flexible and display electronic devices. Low was found to be beneficial to protect the TFT and OLED devices from the external humid environment.

The present invention is applicable to a polyimide substrate and a display substrate module including the same.

Claims (16)

1. Polyimide layer; And

   At least one surface of the polyimide layer comprises a repeating unit represented by the following formula (1-1) and a repeating unit represented by the following formula 1-2 and a silazane-siloxane compound and a repeating unit represented by the formula (2) A polyimide substrate comprising an optical primer layer containing a norbornene resin compound.

   <Formula 1-1>

   

   <Formula 1-2>

   

   In Formulas 1-1 and 1-2, R ₁ is a urethane group, R ₂ is a cyanate group, R ₃ is selected from the group consisting of a hydroxyl group, a vinyl group, an acryl group, an epoxy group and an amine group, m and n is an integer from 1 to 10.

   <Formula 2>

   

   The silazane-siloxane resin is characterized in that the weight average molecular weight of 500 to 500,000 g / mol.
2. The method of claim 1,

   The silazane-siloxane compound is a polyimide substrate, characterized in that the weight average molecular weight of 500 to 500,000 g / mol.
3. The method of claim 1,

   The norbornene resin compound is a polyimide substrate, characterized in that the weight average molecular weight of 500 to 150,000g / mol.
4. The polyimide substrate of claim 1, wherein the silazane-siloxane resin to the norbornene resin compound is included in a weight ratio of 1: 0.1 to 1.0.
5. The polyimide substrate of claim 1, wherein the optical primer layer comprises an acrylic compound.
6. The polyimide substrate according to claim 5, wherein the acrylic compound is contained in an amount of 10 to 200 parts by weight based on 100 parts by weight of the norbornene resin compound.
7. The method of claim 5,

   The acryl-based compound is a trifunctional acrylate monomer dipentaerythritol hexaacrylate (pentaerytritol triacrylate (PETA)), a bifunctional acrylate monomer hexanediol diacrylate (hexanediol diacrylate (HDDA)) and a 6 functional acrylate monomer. A polyimide substrate, characterized in that it is at least one selected from the group consisting of dipentaerythritol hexaacrylate (DIPENTAERYTHRITOL HEXAACRYLATE; DPEHA).
8. The polyimide substrate of claim 1, wherein the optical primer layer has a thickness of 0.1 to 3 μm.
9. The method of claim 1, wherein the optical primer layer is a silazane-siloxane resin compound comprising a repeating unit represented by Formula 1-1 and a repeating unit represented by Formula 1-2 and a repeating unit represented by Formula 2 Forming a film with an optical primer resin solution containing a norbornene resin compound comprising a, a polyimide substrate comprising a step of heat treatment at a temperature of 200 to 300 ℃.
10. The polyimide substrate according to claim 1, wherein the polyimide substrate has a yellowness of 2.5 or less, based on KONICA MINOLTA's CM-3700D measurement, and a light transmittance at 550 nm of 85 to 93%.
11. The polyimide substrate of claim 1, wherein the polyimide substrate further comprises a hard coating layer.
12. The polyimide substrate of claim 11, wherein the hard coating layer is formed from a siloxane resin including a mixture or a chemical reactant of an alkoxy silane represented by Formula 3 and an alkoxy metal represented by Formula 4.

    <Formula 3>

    

    <Formula 4>

    

    In Formulas 3 to 4, R ¹ is a linear, branched, alicyclic, aromatic organic compound including epoxy, acryl, and isocyanate, and R ² and R ³ are linear, including a hetero compound such as oxygen or nitrogen, branched, an alkyl group of alicyclic C ₁ to C _8, n is an integer from 1 to 3. In addition, M is a metal element including a transition metal, and m is an integer of 1-10.
13. The polyimide substrate of claim 11, wherein the hard coating layer has a thickness of 10 to 50 μm.
14. 12. The polyimide substrate of claim 11, wherein the polyimide substrate has a JIS K56000 measurement surface hardness of 5H to 9H.
15. The polyimide substrate of claim 11, wherein the polyimide substrate has an ASTM E96BW measurement moisture permeability of 0.001 to 10 g / m ² * day.
16. A display substrate module comprising a transparent adhesive layer, a black mattress layer and a polyimide substrate according to any one of claims 1 to 15.

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