KR102481278B1 - Multilayer electronic device, heat-resisting film, and manufacturing method thereof - Google Patents

Abstract

상기 식 1에서, 상기 H는 상기 폴리이미드층의 열팽창 계수 (ppm/℃) 값이고, 상기 Y는 상기 폴리이미드층의 10㎛ 두께에서의 황색도 값이고, 상기 R은 상기 폴리이미드층의 10㎛ 두께 기준 550nm에서의 면내 위상차 수치 값이다.
구현예는 내열특성과 광학특성이 동시에 향상된 폴리이미드층을 포함하는 내열필름 등을 제공하여, 보다 얇고 가벼워지면서 동시에 광학적 특성 등이 향상된 다층전자장비를 제공할 수 있다.Embodiments of embodiments of the multi-layer electronic equipment include a substrate layer; a light emitting functional layer disposed on the base layer; and a cover layer disposed on the light emitting functional layer, wherein the base layer includes a polyimide layer having a heat resistance-optical index (HR Index) of 25 to 150 represented by Equation 1 below.
[Equation 1]

In Equation 1, H is the thermal expansion coefficient (ppm/°C) of the polyimide layer, Y is the yellowness value of the polyimide layer at a thickness of 10 μm, and R is 10 μm of the polyimide layer. It is an in-plane retardation numerical value at 550 nm based on the thickness of ㎛.
Embodiments provide a heat-resistant film including a polyimide layer having improved heat-resistance and optical properties at the same time, thereby providing multilayer electronic equipment that is thinner and lighter and has improved optical properties at the same time.

Description

Multi-layer electronic equipment, heat-resisting film and its manufacturing method {MULTILAYER ELECTRONIC DEVICE, HEAT-RESISTING FILM, AND MANUFACTURING METHOD THEREOF}

Embodiments relate to multilayer electronic equipment, a heat-resistant film, and a manufacturing method thereof.

Since polyimide film has excellent heat resistance and mechanical properties, it has a wide range of uses such as coating materials and composite materials. Such a polyimide film is generally prepared by solution polymerization of aromatic diamine and aromatic dianhydride, application in the form of a film and ring closure through dehydration through high-temperature drying steps.

Since the polyimide film has a yellow color due to high aromatic ring density, it has a problem in that it is difficult to use as an optical material due to low transmittance in the visible light region. However, recently, various attempts have been made to apply colorless and transparent polyimide films to optical materials and the like.

As related prior art, there are Korean Patent Publication No. 10-2020-0082203 and Korean Patent Registration No. 10-1430976.

An object of embodiments is to provide a multi-layer electronic device to which a heat-resistant film with improved heat-resistance and optical properties is simultaneously applied. Another object of embodiments is to provide a heat-resistant film including a polyimide layer having improved heat-resistant properties and optical properties at the same time. Another object of embodiments is to provide a method for manufacturing the heat-resistant film and the like.

In order to achieve the above object, a multilayer electronic device according to an embodiment of the embodiment includes a base layer; a light emitting functional layer disposed on the base layer; and a cover layer disposed on the light emitting functional layer, wherein the substrate layer includes a heat-resistant film, and the heat-resistant film includes a polyimide layer.

In order to achieve the above object, the heat-resistant film according to one embodiment of the embodiment includes a polyimide layer.

The polyimide layer may have a heat resistance-optical index (H-R Index) of 25 to 150 represented by Equation 1 below.

[Equation 1]

In Equation 1, H is the thermal expansion coefficient (ppm/°C) of the polyimide layer, Y is the yellowness value of the polyimide layer at a thickness of 10 μm, and R is 10 μm of the polyimide layer. It is an in-plane retardation numerical value at 550 nm based on the thickness of ㎛.

The polyimide layer may have a yellowness of 7 or less.

The polyimide layer may have a thickness variation of 5% or less.

The polyimide layer may have an in-plane retardation of 3.0 or less at 550 nm.

The polyimide layer may have an optical index (R Index) of 11 or less represented by Equation 2 below.

[Equation 2]

In Equation 2, Y is a yellowness value at a thickness of 10 μm of the polyimide layer, and R is an in-plane retardation value at 550 nm based on a thickness of 10 μm of the polyimide layer.

A temperature (° C.) at a time when 5% by weight of the polyimide layer is reduced may be 550° C. or more.

Td5 is the temperature (° C.) at which 5% by weight of the polyimide layer is reduced.

Td1 is the temperature (° C.) at which 1% by weight of the polyimide layer is reduced.

In the polyimide layer, a value obtained by subtracting the Td1 from the Td5 may be 70 °C or less.

The polyimide layer may include hexafluoroisopropylidenediphthalic anhydride residues and pyromellitic acid anhydride residues in a molar ratio of 1:0.5 to 1.9.

In order to achieve the above object, a method for producing a heat-resistant film according to an embodiment of the present invention prepares a polymer solution having a viscosity of 1,000 to 9,000 cps measured at 25 ° C. by stirring a raw material composition containing diamine and dianhydride. preparing a polymer solution; Sheet manufacturing step of preparing a sheet by applying the polymer solution in the form of a sheet and then drying with hot air; and a film manufacturing step of preparing a polyimide film by heat-treating the sheet at 150 to 500° C., wherein the heat-resistant film includes the polyimide film.

The step of preparing the polymer solution may include a reaction process and an aging process.

The reaction process is a process of forming a reaction solution by inducing a reaction in the raw material composition while stirring the raw material composition in an organic solvent.

The aging process is a process of preparing the polymer solution by storing the reaction solution at 10 to 35 ° C. for 4 to 20 hours.

Embodiments of multilayer electronic equipment, heat-resistant film, and manufacturing method thereof provide a heat-resistant film including a polyimide layer having improved heat resistance and optical properties at the same time, thereby providing multilayer electronic equipment that is thinner and lighter and has improved optical properties at the same time. can In addition, it is possible to provide a method of manufacturing a heat-resistant film with improved workability by providing a reliable manufacturing method.

1 is a conceptual diagram illustrating a layer structure of a multi-layer electronic equipment according to an embodiment in cross section;
2 and 3 are conceptual views illustrating a layer structure of a heat-resistant film according to an embodiment in a cross-section, respectively.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. Like reference numerals have been assigned to like parts throughout the specification.

In this specification, when a certain component "includes" another component, this means that it may further include other components without excluding other components unless otherwise specified.

In this specification, when a component is said to be "connected" to another component, this includes not only the case of being 'directly connected', but also the case of being 'connected with another component intervening therebetween'.

In the present specification, the meaning that B is located on A means that B is located directly on A or B is located on A while another component is located therebetween, and B is located on the surface of A. It is not construed as being limited to

In this specification, the term "combination of these" included in the expression of the Markush form means a mixture or combination of one or more selected from the group consisting of the components described in the expression of the Markush form, It means including one or more selected from the group consisting of.

In this specification, description of "A and/or B" means "A, B, or A and B".

In this specification, terms such as "first", "second", or "A" and "B" are used to distinguish the same terms from each other unless otherwise specified.

In this specification, a singular expression is interpreted as a meaning including a singular number or a plurality interpreted in context unless otherwise specified.

In this specification, the relative size, thickness, etc. of components shown in the drawings may be exaggerated for the purpose of easy description.

In this specification, yellowness (Y.I.) uses the CIE colorimetric system of a spectrophotometer (Hunter Associates Laboratory Co., Ltd. UltraScan PRO) and is based on a value calculated according to ASTM E-313 standard.

In this specification, the viscosity presented without mentioning a specific temperature means the viscosity measured at room temperature, and exemplarily refers to the viscosity measured at 25 °C.

Hereinafter, an embodiment will be described in more detail.

A polyimide film has characteristics of a colored film close to brown in the case of a film having excellent heat resistance, and has characteristics of poor heat resistance in the case of a transparent film, so that heat resistance and transparency are in a trade-off relationship with each other.

Polyimide film is used as an insulating layer of electronic products based on the insulating properties of polyimide film. In addition, attempts to apply it to a flexible display or foldable display based on the foldable or flexible characteristics of the plastic film itself and the insulating characteristics of the polyimide film are continuing. The inventors manufacture a polyimide film with excellent optical properties and heat resistance properties at the same time, confirm that the polyimide film is excellent in physical properties and usability when used as a base film for a flexible or foldable display, and present an embodiment. .

1 is a conceptual diagram illustrating a layer structure of a multilayer electronic device in cross section according to an embodiment, and FIGS. 2 and 3 are conceptual views illustrating a layer structure of a heat-resistant film in a cross section according to an embodiment. Referring to FIGS. 1 to 3 , the multilayer electronic equipment 800 and the heat resistant film 100 will be described in detail below.

multilayer electronic equipment

In order to achieve the above object, the multilayer electronic equipment 800 according to one embodiment of the embodiment includes a base layer 100; a light emitting functional layer 300 disposed on the base layer; and a cover layer 500 disposed on the light-emitting functional layer, and the base layer 100 includes a heat-resistant film 100 described below.

The multilayer electronic equipment 800 may be a display device.

The multilayer electronic equipment 800 may be a large area display device, a foldable display device, a bendable display device, or a flexible display device.

The multilayer electronic equipment 800 may be, for example, a bendable mobile communication device (eg, a mobile phone) or a bendable laptop computer.

The light-emitting functional layer 300 includes a color-emitting layer (not shown) having a device that emits light according to a signal. Illustratively, the light emitting functional layer includes a signal transmission layer (not shown) that transmits an external electrical signal to the color layer, and a color layer (not shown) that is disposed on the signal transmission layer and emits color according to a given signal. , It may include an encapsulation layer (not shown) that protects the color layer. The signal transmission layer (not shown) may include a thin film transistor (TFT), and illustratively, LTPS, a-SiTFT, or oxide TFT may be applied, but is not limited thereto. The encapsulation layer (not shown) may be applied with TFE (Thin Film Encapsulation), but is not limited thereto.

The color layer may be a self-luminous color layer. Illustratively, QLED (Quantum dot light-emitting diodes), OLED (Organic Light Emitting Diodes), etc. may be applied to the color layer, but is not limited thereto.

The light emitting functional layer 300 may include a sensor layer (not shown). Illustratively, a touch sensor or the like may be applied. The sensor layer may be disposed above or below the chromogenic layer.

The light emitting functional layer 300 may further include a polarization layer (not shown). A polarization layer may be disposed above or below the color development layer.

The light emitting functional layer 300 may further include a color filter layer (not shown). A color filter layer may be disposed above or below the color development layer.

The light emitting functional layer 300 may be disposed on the base layer 100 .

A cover layer 500 may be disposed on the light emitting functional layer 300 .

As the cover layer 500, a plastic film, glass, etc. applied as a cover layer of a display device may be applied.

An adhesive layer (not shown) may be further applied between the light emitting functional layer 300 and the cover layer 500 .

The cover layer 500 may further include an electrode layer (not shown) according to the type of light emitting device applied to the light emitting functional layer. The electrode layer is disposed on one surface of the light emitting functional layer, and an optical adhesive layer may or may not be disposed between the electrode layer and the light emitting functional layer. The electrode layer may be a transparent metal layer, and it is preferable to apply a transparent metal layer having a sealing function. The electrode layer may induce driving of the light emitting layer of the light emitting functional layer while passing light emitted from the light emitting functional layer. Illustratively, the electrode layer may be applied as a cathode of the light emitting functional layer. In the case of having an electrode layer on one surface of the light emitting layer and a signal transmission layer under the other surface of the light emitting layer, the structure is good for applying a light emitting functional layer such as OLED.

The base layer 100 includes a heat-resistant film 100 .

The base layer 100 includes a polyimide layer 50 .

The base layer 100 may include a polyimide layer 50 and an adhesive layer 60 positioned on the polyimide layer.

The adhesive layer 60 may be an optical adhesive layer having excellent light transmittance and/or transparency. Illustratively, the adhesive layer may be applied with a laminate including optically clear adhesive (OCA), pressure sensitive adhesive (PSA), or a combination thereof.

Since a detailed description of the heat-resistant film and the polyimide layer overlaps with the description below, a detailed description thereof will be omitted.

If necessary, the multilayer electronic equipment may further include an additional boundary layer (not shown) under the base layer, or may be further connected to a supporting means (or driving means) of a rollable or bendable display.

If necessary, the multilayer electronic equipment may further connect a driving means (or support means) of an additional rollable or bendable display on the cover layer.

The driving means or support means can be applied without limitation as long as it is applied to a rollable or bendable display.

heat resistant film

The heat-resistant film 100 according to an embodiment includes a polyimide layer having a heat-resistant-optical index (H-R Index) of 25 to 150 represented by Equation 1 below.

[Equation 1]

In Equation 1, H is the thermal expansion coefficient (ppm/°C) of the polyimide layer, Y is the yellowness value of the polyimide layer at a thickness of 10 μm, and R is 10 μm of the polyimide layer. It is an in-plane retardation numerical value at 550 nm based on the thickness of ㎛.

The polyimide layer 50 has heat resistance and excellent optical characteristics.

The heat resistance-optical index means that various characteristics obtained from the same polyimide layer, such as yellowness, in-plane retardation, and thermal expansion coefficient, which are difficult to satisfy at the same time, can be obtained at a certain level or higher.

The heat resistance-optical index of the polyimide layer 50 may be 25 or more, 40 or more, or 60 or more. The heat resistance-optical index of the polyimide layer 50 may be 150 or less, or 140 or less. The heat resistance-optical index of the polyimide layer 50 may be in the range of 110 to 140. The polyimide layer having a heat-resistant optical index within this range can simultaneously obtain a thermal expansion coefficient, yellowness, and in-plane retardation above a certain level, which are difficult to obtain excellent physical properties at the same time.

The polyimide layer 50 may have a thermal expansion coefficient (ppm/°C) of 60 or less, or 50 or less. The polyimide layer 50 may have a thermal expansion coefficient (ppm/°C) of 45 or less, or 30 or less. In addition, the polyimide layer 50 may have a coefficient of thermal expansion (ppm/°C) of 20 or more. In the case of having such a thermal expansion coefficient value, the heat resistance property is relatively good.

The polyimide layer 50 may have a thickness of 2 to 100 μm, 2 to 55 μm, or more than 2 μm to less than 40 μm. The following optical characteristics are described based on the polyimide layer having such a thickness.

The polyimide layer 50 may have a haze of 2% or less, 1.5% or less, 1% or less, or 0.5% or less. The polyimide layer 50 may have a haze of 0.001% or more. The polyimide layer having such haze characteristics has optical characteristics that appear clear to the naked eye, and is excellent for application as a base film for displays and the like.

The polyimide layer 50 may have a yellowness of 7 or less, a yellowness of 6 or less, or a yellowness of 5 or less. The polyimide layer 50 may have a yellowness of greater than 1.

The polyimide layer 50 may have light transmittance of 85% or more, 88% or more, or 99% or less. The light transmittance is based on visible light transmittance.

The polyimide layer 50 may have an in-plane retardation value (Re) of 3.0 or less, 2.0 or less, 1.5 or less, or 1.0 or less. The polyimide layer 50 may have an in-plane retardation value (Re) of 0.1 or more. The in-plane retardation value is measured by selecting Alpha / Theta mode in the Rotate Analyzer Method at room temperature using the RETS-100 model of OTSUKA Electronics, and the in-plane retardation Re value at 550 nm is taken. A polyimide layer having an in-plane retardation value within the above-mentioned range has excellent optical properties.

The polyimide layer may have an optical index (R Index) of 11 or less represented by Equation 2 below.

[Equation 2]

In Equation 2, Y is a yellowness value at a thickness of 10 μm of the polyimide layer, and R is an in-plane retardation value at 550 nm based on a thickness of 10 μm of the polyimide layer.

The optical index may be 3 or more, 8 or less, or 7 or less. The polyimide layer having the optical index within this range can maintain a thermal expansion coefficient and in-plane retardation above a certain level, which are difficult to obtain excellent physical properties at the same time.

The polyimide layer 50 may have a glass transition temperature of 375 °C or higher, 380 °C or higher, or 382 °C or higher. The polyimide layer 50 may have a glass transition temperature of 410 °C or less and 400 °C or less. This glass transition temperature is higher than the glass transition temperature of the existing polyimide layer, and the microstructure of the polymer changes due to various influences such as viscosity control, temperature and atmosphere control in the manufacturing process such as polymerization and drying process. , it is considered that the glass transition temperature has the above range due to these influences.

The polyimide layer 50 has a constant thickness throughout the area. Specifically, the polyimide layer 50 divides the polyimide layer into 40 regions with substantially equal areas, and the thickness measured at 40 points, one point in each region, is the average value of the thicknesses measured at the 40 points. The thickness uniformity is excellent within the range of -5 to +5% of the contrast.

The polyimide layer 50 has excellent heat resistance properties as well as the above-mentioned optical properties.

In the polyimide layer 50, a value obtained by subtracting the Td1 from the Td5 may be 70 °C or less. In the polyimide layer 50, a value obtained by subtracting the Td1 from the Td5 may be 65 °C or less, 60 °C or less, or 55 °C or less. In the polyimide layer 50, a value obtained by subtracting the Td1 from the Td5 may be 25 °C or higher. In the polyimide layer 50, a value obtained by subtracting the Td1 from the Td5 may be 30 °C or higher, 35 °C or higher, or 40 °C or higher. The polyimide layer having these characteristics has substantially excellent heat resistance.

The temperature (°C, Td5) at the time when 5% by weight of the entire polyimide layer 50 is reduced may be 550°C or higher, 555°C or higher, or 560°C or higher. A temperature (°C, Td5) at a time when 5% by weight of the entire polyimide layer is reduced may be less than 600°C. In addition, the temperature (° C., Td1) at the time when 1% by weight of the entire polyimide layer 50 is reduced may be 500° C. or more and may be less than 515° C. A polyimide layer having these characteristics has excellent heat resistance characteristics.

The polyimide layer 50 having a heat resistance transparency index (H-T Index) represented by Equation 3 below is 8 or more.

[Equation 3]

In Equation 3, Td5 is the temperature (°C) at which 5% by weight of the entire polyimide layer 50 is reduced, and Td1 is the time when 1% by weight of the entire polyimide layer 50 is reduced. is the temperature (° C.), and YI is the yellow index value based on the 10 μm thickness of the polyimide layer 50.

The polyimide layer 50 may have a heat resistance transparency index (H-T Index) of 20 or less, 18 or less, or 16 or less. The polyimide layer 50 may have a heat resistance transparency index (H-T Index) of 8 or more, or 10 or more.

When the polyimide layer 50 has the above-described heat-resistant transparency index, a heat-resistant film having excellent heat resistance and optical properties, particularly yellowness, can be provided.

The polyimide layer 50 includes a polymer formed by polymerizing an aromatic diamine compound and an aromatic dianhydride compound.

The aromatic diamine compound is 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (TFMB), 2,2-bis (4- (4-aminophenoxy) phenyl) hexafluoro Lopropane (HFBAPP), 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether (BTFDPE), 2,2-bis(4-(4-amino-2-(tri) fluoromethyl)phenoxy)phenyl)hexafluoropropane (HFFAPP), or 3,5-diaminobenzotrifluoride (DATF).

Specifically, the aromatic diamine compound may be a compound represented by Chemical Formula 1-1 below.

[Formula 1-1]

The aromatic dianhydride compound is 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6-FDA), 4,4'-oxydiphthalic anhydride (ODPA), 2 ,3,3',4'-biphenyltetracarboxylic acid dianhydride (BPDA), philomellitic dianhydride (PMDA), and any one selected from the group consisting of combinations thereof may be included.

Specifically, the aromatic dianhydride compound may be applied together with the compounds represented by Chemical Formulas 2-1 and 2-2 below.

[Formula 2-1]

[Formula 2-2]

The aromatic diamine compound and the aromatic dianhydride compound may react in a molar ratio of 1:0.95 to 1.05 to form a polymer.

The compound of Formula 2-1 and the compound of Formula 2-2 may be included in a molar ratio of 1:0.5 to 1.9. When the compound of Chemical Formula 2-1 and the compound of Chemical Formula 2-2 are applied together in the above ratio, heat resistance and optical characteristics can be simultaneously improved.

The polyimide layer 50 may include hexafluoroisopropylidenediphthalic anhydride residues and pyromellitic acid anhydride residues in a molar ratio of 1:0.5 to 1.9.

The polyimide layer 50 contains a 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl residue and a hexafluoroisopropylidenediphthalic anhydride residue in a ratio of 1:0.35 to 0.65. It may be included in a molar ratio of

The polyimide layer 50 may include 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl residue and pyromellitic acid anhydride residue in a molar ratio of 1:0.35 to 0.65. can

When the polyimide layer containing the residues in the above ratio is applied to the heat-resistant film, it is possible to simultaneously satisfy heat resistance and optical properties, while improving process efficiency and workability.

The heat-resistant film 100 may further include an adhesive layer 60 on one surface of the polyimide layer. The adhesive layer 60 may be an optical adhesive layer having excellent light transmittance and/or transparency. Illustratively, a laminate including optically clear adhesive (OCA), pressure sensitive adhesive (PSA), or a combination thereof may be applied.

The heat-resistant film 100 may further include a release film or a reinforcement film on the other surface of the polyimide layer.

The heat-resistant film 100 includes the polyimide layer described above, and simultaneously satisfies heat-resistant properties and optical properties and serves as a support layer, and is excellent in utilization as a base layer. In addition, when the heat-resistant film is used as a substrate layer, not only the upper surface of the light emitting functional layer corresponding to the front surface of multilayer electronic equipment but also the substrate layer corresponding to the back surface can be manufactured transparently, so that foldable, flexible, It is excellent in utilization in bendable devices and can provide a reliable heat-resistant film in terms of heat resistance, thickness, insulation characteristics, and support characteristics.

Manufacturing method of heat-resistant film

A method of manufacturing a heat-resistant film according to an embodiment includes preparing a polymer solution; sheet manufacturing step; And a film manufacturing step; includes.

The polymer solution preparation step is a step of preparing a polymer solution by stirring a raw material composition containing diamine and dianhydride. The step of preparing the polymer solution may include a reaction process and an aging process.

The diamine may be an aromatic diamine compound.

The diamine may include one or more aromatic diamine compounds.

The dianhydride may be an aromatic dianhydride compound.

The dianhydride may include two or more types of aromatic dianhydride compounds.

Since the contents of the aromatic diamine compound, the type of the aromatic dianhydride compound, the application ratio, etc. overlap with the above description, the description thereof is omitted.

The reaction process is a process of inducing an imidation reaction while stirring the raw material composition in an organic solvent. A product in the above reaction process is referred to as a reaction solution for convenience.

In the organic solvent, the solid content of the raw material composition may be 10 to 40% by weight, 15 to 30% by weight, or 18 to 25% by weight. Workability is better when it has such a solid content.

Agitation of the raw material composition may be divided into primary stirring and secondary stirring.

The primary stirring is a step of inducing a reaction while stirring an aromatic diamine compound containing a halogen element in a molecule and an aromatic anhydride compound containing a halogen element in a molecule in an organic solvent, at a reaction temperature of 1 to 30 ° C. 10 minutes to 10 hours may proceed during the reaction time. Preferably, 10 minutes to 10 hours at a reaction temperature of 1 to 9 ° C. may be performed during the reaction time.

The secondary stirring is a step of inducing a reaction while stirring the reaction product of the first stirring and an aromatic anhydride compound having no halogen element in the molecule. The secondary stirring may be performed at a reaction temperature of 30 to 70 °C for a reaction time of 30 minutes to 10 hours.

A reaction solution may be prepared through this process.

The aging process is a process of storing the reaction solution to form a polymer solution having a certain viscosity. The aging process may be a process of storing at 10 to 35 ° C. for 4 to 20 hours. The aging process may be a process of storing for 6 to 16 hours at 15 to 30 ℃. The aging process may be a process of storing for 8 to 15 hours at 20 to 28 ℃.

The aging process may facilitate obtaining a polymer solution having an intended viscosity by allowing the reaction to proceed slowly after the reaction process. In addition, it was experimentally confirmed that a difference may occur in physical properties including the glass transition temperature of the polyimide layer formed in contrast to the case where the aging process was not performed. Through this, it is thought that, when the above-described appropriate aging process is further performed, it is possible to obtain a polyimide layer with better physical properties by affecting the control of the polymer structure of the polyimide layer to be produced.

The completion of preparation of the polymer solution can be confirmed by measuring the viscosity of the polymer solution. The polymer solution, as a precursor of the polyimide layer, should be easy to coat, suitable for forming a layer having a constant thickness, and should also have excellent optical properties. Therefore, considering workability and physical properties, etc., it is good to induce a reaction to have a viscosity of 1,000 to 9,000 cps based on the value measured at 25 ° C, and to prepare a polymer solution having a viscosity of 2,000 cps or more and less than 5,000 cps, It is more preferably less than 3,000 cps to 4,500 cps. If the viscosity is too low, less than 1,000 cps, it may be difficult to prepare the polyimide layer to have a certain thickness or an intended thickness, and heat resistance may be insufficient. When it exceeds 9,000 cps, gelation occurs, and film formation may be substantially difficult.

Additional additives, process stabilizers, etc. may be added to the polymer solution as needed. The additive, the process stabilizer, etc. may be applied without limitation as long as they are applied to polyimide polymerization.

The sheet manufacturing step is a step of preparing a dry sheet by applying the polymer solution in the form of a sheet and then drying with hot air.

The polymer solution is applied to a substrate such as a glass plate, and drying is performed at a drying temperature and for a drying time. The drying temperature is exemplarily 100 to 180 °C, and the drying time may be 3 to 60 minutes. The drying may be performed in an inert atmosphere or a vacuum oven to control the optical properties of the polyimide layer.

The film manufacturing step is a step of preparing a polyimide film by heat-treating the sheet.

The heat treatment may be performed by applying a heat treatment temperature and a heat treatment temperature increase rate.

The heat treatment temperature may be 150 to 450 °C, 300 to 430 °C, or 360 to 420 °C. A heating rate up to the heat treatment temperature may be 3 to 25 °C/min, 10 to 20 °C/min, or 13 to 17 °C/min. When such a heat treatment temperature and temperature increase rate are applied, the degree of polymerization is controlled so as to have desired physical properties of the produced film, and more stable heat treatment can be performed.

The heat treatment has an advantage in that it can be performed not only under an inert atmosphere but also under an air atmosphere. Embodiments also have excellent optical properties even when heat treatment is performed in an air atmosphere, so process workability is further improved.

The heat-resistant film manufactured by the manufacturing method includes the polyimide film. The polyimide film has the characteristics of the polyimide layer included in the above heat-resistant film as it is.

Hereinafter, it will be described in more detail through specific examples. The following examples are merely examples to aid understanding of the present invention, and the scope of the present invention is not limited thereto.

Production of polyimide layer A

(Example 1)

After filling 458g of NMP (N-Methyl-2-Pyrrolidone), an organic solvent, in a temperature-controlled double-jacketed 1L glass reactor under a nitrogen atmosphere at 40 ° C, aromatic diamine, 2,2'-bis (trifluoromethyl) ) -4,4'-diaminobiphenyl (TFDB) was dissolved while slowly adding 0.170 mol. Subsequently, 0.102 mol of 4,4′-(hexafluoroisopropylidene) diphthalic anhydride (6-FDA) was slowly added while stirring at 5° C. for 3 hours. After adding 0.068 mol of PMDA (Pyromellitic dianhydride), the mixture was stirred at 50 °C for 4 hours, and then stored at 25 °C for 12 hours to mature. Then, the viscosity at room temperature was measured.

After measuring the viscosity, an additive and a process stabilizer were additionally added and stirred for 4 hours to obtain a polymer solution. After coating the polymer solution on a glass plate, it was dried in a vacuum oven at 150° C. for 10 minutes. Thereafter, the temperature was raised at a rate of 15 ° C / min in the temperature range of 150 ° C to 400 ° C, and cured in an air atmosphere (hot air oven) at 400 ° C, finally obtaining a polyamide film having a thickness of 10 μm, which was obtained in Example 1. applied as a mid-layer.

(Examples 2-3 and Comparative Examples 1-2)

In the case of Examples 2 and 3 and Comparative Examples 1 and 2, polyimide layers were prepared by the manufacturing method of Example 1, but raw materials were added according to the composition shown in Table 1.

(Comparative Example 3)

Other conditions were the same as in Example 3, but Comparative Example 3 was prepared by applying different viscosity and curing temperature. Specific conditions are as described in Tables 1 and 2.

The table below shows values converted based on 100 moles of diamine content.

Ingredients: Content
(molar ratio) Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Diamine TFMB 100 100 100 100 100 100 dianhydride 6FDA 60 50 40 70 80 40 PMDA 40 50 60 30 20 60 of dianhydride
mole ratio* Standard: 6FDA 0.667 1.000 1.500 0.429 0.250 1.500

* Displayed only up to 3 decimal places.

Evaluation of physical properties of polyimide film A

The physical properties of Examples 1 to 3 and Comparative Examples 1 to 3 were evaluated by the measurement method below, and the results are shown in Table 2 below.

(1) Thickness was measured using a digital micrometer 547-401 from Mitutoyo Co., Ltd. in Japan, measuring the thickness of 10 points at random locations and measuring the thickness as an average value. In the case of thickness deviation, divide the area into 40 using the above device, measure the thickness at 40 points by taking a point from the center of each point, and if the average value of the total value is in the range of -5 to +5% P, if it is out of the above range, it is marked as F.

(2) For yellowness (YI), the CIE colorimetric system of a spectrophotometer (Hunter Associates Laboratory, UltraScan PRO) was used. YI was calculated according to the ASTM E-313 standard.

(3) Transmittance and haze were measured according to the JIS K 7105 standard using a haze meter NDH-5000W from Denshoku Kogyo, Japan. Light transmittance (%) and haze (%) were measured.

(4) Viscosity was measured by maintaining the temperature of the polymer solution (varnish) at 25° C., and using a TOKI SANGYO BH-II Model viscometer. RPM was set to 4, and it was confirmed that the target viscosity was implemented using spindle number 4.

(5) Td1 and Td5 were subjected to thermal analysis by taking 2 g of measurement sample using TA's TGA (Thermal Gravimetric Analysis) model Q500. Starting at 25 °C, the analysis was performed at a heating rate of 10 °C/min to 700 °C to obtain mass loss data according to temperature. At the time of analysis, the sample weight at 25 ° C was assumed to be 100%, and the temperature at which 1% of the weight was reduced was defined as Td1, and the temperature at which 5% of the weight was reduced was defined as Td5.

(6) Thermal expansion coefficient (CTE) was measured using a thermal expansion coefficient measuring instrument, and specifically, Seiko Exstar 6000 (TMA6100) Model from SEICO INST. (JAPAN) was used. The measurement method/conditions are as follows, and the amount of change between 50 and 250 based on 2nd Heat was defined as the CTE value.

* After heating from 30℃ to 350℃ (heating rate of 5 ℃/min or more, 1st heating), cool again to 50℃.

* Heating from 50℃ to 450℃ (heating rate 5 ℃/min or more, 2nd heating).

(7) In-plane retardation was measured at room temperature using the RETS-100 model of OTSUKA Electronics. It was measured by selecting the Alpha/Theta mode in the Rotate Analyzer Method, and the in-plane retardation Re value at 550 nm was measured at room temperature and shown in the table below.

(8) The heat resistance-optical index (H-R Index) was calculated according to Equation 1.

[Equation 1]

In Equation 1, H is the thermal expansion coefficient (ppm/°C) of the polyimide layer, Y is the yellowness value of the polyimide layer at a thickness of 10 μm, and R is 10 μm of the polyimide layer. It is an in-plane retardation numerical value at 550 nm based on the thickness of ㎛.

(9) The optical index (R Index) was calculated according to Equation 2 below.

[Equation 2]

In Equation 2, Y is a yellowness value at a thickness of 10 μm of the polyimide layer, and R is an in-plane retardation value at 550 nm based on a thickness of 10 μm of the polyimide layer.

evaluation items Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Viscosity (CPS @ 25°C)* 4,000 3,750 7,500 1,600 200 200 Thickness (㎛) 10 10 10 10 about 10 about 10 thickness deviation P P P P F P Curing conditions (℃)
Standby, hot air oven 400 400 400 400 400 500 Tg 383 389 398 372 366 ND TT (%) 90.4 89.9 89.8 90.6 91.3 89.8 Haze (%) 0.31 0.4 0.8 0.3 0.2 0.7 YI 3.1 4.3 4.5 4.4 2.3 8.9 Re 1.1 1.47 0.68 1.62 4.5 0.68 CTE 46.5 43 27.1 57.9 81.6 27.5 Td1 502 505 506 498 489 506 Td5 551 558 561 521 505 561 Td5-Td1 49 53 55 23 16 55 Heat resistance-optical index (H-R Index) 131 125.8 132.6 157.3 21.7 319 Optical Index (R Index) 6.51 10.62 7.56 11.53 12.65 14.95

* Viscosity means the viscosity of the polymer solution. Among the evaluation items, items other than viscosity were measured for the film. ND means no measurement.

Referring to Tables 1 and 2, Comparative Example 3 had a high heat-resistance-optical index and a relatively high yellowness, and was considered not suitable for application to multilayer electronic equipment for displays.

In addition, when considering 6FDA as the criterion (1), it was confirmed that when the molar ratio of PMDA was less than 0.538, it was difficult to control the thickness of the film or the heat resistance was substantially inferior. That is, in the case of Comparative Example 1 and Comparative Example 2, the viscosity was low, resulting in uneven thickness or slightly inferior heat resistance compared to other examples.

In the case of Examples 1 to 3, although there was a slight difference in kurtosis, it was confirmed that they showed processability suitable for film formation, and both optical properties and heat resistance properties were excellent.

It seems that the difference in curing conditions affects physical properties such as heat resistance, and it was confirmed that even when curing is performed in an atmospheric atmosphere at about 400 ° C., it has excellent heat resistance and transparency at the same time. At 500 ℃, it was confirmed that the optical properties deteriorated rapidly when curing was performed in an atmospheric atmosphere.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concept of the present invention defined in the following claims are also made according to the present invention. falls within the scope of the rights of

[Company information]
This invention was invented with the support of the Korea Evaluation Institute of Industrial Technology material parts technology development project (package type, task number 20007228).

100: base layer 300: light emitting functional layer
500: cover layer 800: multilayer electronic equipment
50: polyimide layer 60: adhesive layer

Claims (11)

base layer;
a light emitting functional layer disposed on the base layer; and
Including; a cover layer disposed on the light emitting functional layer,
The base layer includes a heat-resistant film,
The heat-resistant film includes a polyimide layer having a heat-resistant-optical index (HR Index) of 25 to 150 represented by Equation 1 below,
The polyimide layer includes hexafluoroisopropylidenediphthalic anhydride residues and pyromellitic acid anhydride residues in a molar ratio of 1:0.5 to 1.9,
The glass transition temperature of the polyimide layer is 375 ° C. or higher,
Multi-layer electronic equipment, wherein the polyimide layer has a yellowness of 5 or less;
[Equation 1]

In Equation 1 above,
The H is the thermal expansion coefficient (ppm / ℃) value of the polyimide layer,
Y is the yellowness value of the polyimide layer at a thickness of 10 μm,
The R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
delete According to claim 1,
The polyimide layer has a thickness deviation of less than 5%, multi-layer electronic equipment.
According to claim 1,
The polyimide layer has an in-plane retardation of 3.0 or less at 550 nm, multilayer electronic equipment.
According to claim 1,
The polyimide layer has an optical index (R Index) represented by Equation 2 below of 11 or less, multi-layer electronic equipment;
[Equation 2]

In Equation 2 above,
Y is the yellowness value of the polyimide layer at a thickness of 10 μm,
The R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
A polyimide layer having a heat resistance-optical index (HR Index) of 25 to 150 represented by Equation 1 below,
The polyimide layer includes hexafluoroisopropylidenediphthalic anhydride residues and pyromellitic acid anhydride residues in a molar ratio of 1:0.5 to 1.9,
The glass transition temperature of the polyimide layer is 375 ° C. or higher,
a heat-resistant film having a yellowness of the polyimide layer of 5 or less;
[Equation 1]

In Equation 1 above,
The H is the thermal expansion coefficient (ppm / ℃) value of the polyimide layer,
Y is the yellowness value of the polyimide layer at a thickness of 10 μm,
The R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
According to claim 6,
A heat-resistant film having a temperature (° C.) of 550° C. or higher at a time when 5% by weight of the polyimide layer is reduced.
According to claim 6,
Td5 is the temperature (° C.) at which 5% by weight of the polyimide layer is reduced,
Td1 is the temperature (° C.) at which 1% by weight of the polyimide layer is reduced,
The heat-resistant film, wherein the value obtained by subtracting the Td1 from the Td5 is 70 °C or less.
delete A polymer solution preparation step of preparing a polymer solution having a viscosity of 1,000 to 9,000 cps measured at 25 ° C. by stirring a raw material composition containing diamine and dianhydride;
Sheet manufacturing step of preparing a sheet by applying the polymer solution in the form of a sheet and then drying with hot air; and
A film manufacturing step of preparing a polyimide layer by heat-treating the sheet at 150 to 500 ° C.; Including,
The heat-resistant film includes the polyimide layer,
The polyimide layer has a heat resistance-optical index (HR Index) of 25 to 150 represented by Equation 1 below,
The polyimide layer includes hexafluoroisopropylidenediphthalic anhydride residues and pyromellitic acid anhydride residues in a molar ratio of 1:0.5 to 1.9,
The glass transition temperature of the polyimide layer is 375 ° C. or higher,
A method for producing a heat-resistant film in which the yellowness of the polyimide layer is 5 or less;
[Equation 1]

In Equation 1 above,
The H is the thermal expansion coefficient (ppm / ℃) value of the polyimide layer,
Y is the yellowness value of the polyimide layer at a thickness of 10 μm,
The R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
According to claim 10,
The polymer solution preparation step includes a reaction process and an aging process,
The reaction process is a process of forming a reaction solution by inducing a reaction in the raw material composition while stirring the raw material composition in an organic solvent,
The aging process is a process of preparing the polymer solution by storing the reaction solution at 10 to 35 ° C. for 4 to 20 hours, a method for producing a heat-resistant film.

Images