KR20220095829A - Multilayer electronic device, heat-resisting film, and manufacturing method thereof - Google Patents

Abstract

A multilayer electronic device of an 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. The base layer includes a polyimide layer having a heat resistance-optical index (H-R Index) of 25 to 150 represented by equation 1, H - R Index = H * Y / R. In equation 1, H is a thermal expansion coefficient (ppm/℃) value of the polyimide layer, Y is a yellowness value of the polyimide layer at a thickness of 10 μm, and R is an in-plane retardation numerical value at 550 nm with reference to a 10 μm thickness of the polyimide layer. 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 device that is thinner and lighter and has improved optical properties at the same time.

Description

Multilayer electronic equipment, heat-resistant film and manufacturing method thereof

The embodiment relates to a multilayer electronic device, a heat-resistant film, and a method for manufacturing the same.

Because 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, coating in the form of a film, drying at high temperature, and ring closure through dehydration.

Since the polyimide film has a yellow color due to its high aromatic ring density, it has a low transmittance in the visible light region, making it difficult to use as an optical material. However, in recent years, a colorless and transparent polyimide film has been manufactured and various attempts have been made to apply it as an optical material.

As related prior art, there are Republic of Korea Patent Publication No. 10-2020-0082203, Korean Patent Registration No. 10-1430976, and the like.

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

In order to achieve the above object, a multi-layer 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 base 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 an embodiment of the present invention includes a polyimide layer.

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

[Equation 1]

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

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

The thickness deviation of the polyimide layer may be within 5%.

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 expressed 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 a numerical value of in-plane retardation at 550 nm based on a thickness of 10 μm of the polyimide layer.

A temperature (°C) at which 5 wt% of the polyimide layer is reduced may be 550°C or higher.

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

Td1 is the temperature (°C) at which 1 wt% 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 residue and pyromellitic acid anhydride residue in a molar ratio of 1: 0.5 to 1.9.

In order to achieve the above object, in the method for manufacturing a heat-resistant film according to an embodiment of the embodiment, a polymer solution having a viscosity of 1,000 to 9,000 cps measured at 25° C. is prepared by stirring a raw material composition containing diamine and dianhydride a polymer solution preparation step; a sheet manufacturing step of applying the polymer solution in the form of a sheet and then drying the sheet with hot air; and a film manufacturing step of manufacturing 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 inducing a reaction in the raw material composition while stirring the raw material composition in an organic solvent to form a reaction solution.

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.

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

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

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily carry out the present invention. However, the present invention may be embodied in several different forms and is not limited to the embodiments described herein. Throughout the specification, like reference numerals are assigned to similar parts.

In the present specification, when a certain component "includes" another component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In the present specification, when a component is "connected" with another component, this includes not only the case of 'directly connected', but also the case of 'connected with another component in the middle'.

In this specification, the meaning that B is positioned on A means that B is positioned so that it directly abuts on A or that B is positioned on A while other configurations are positioned therebetween, and B is positioned so that it abuts 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 one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It means to include one or more selected from the group consisting of.

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

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

In the present specification, unless otherwise specified, the expression “a” is interpreted as meaning including “a” or “plural” as interpreted in context.

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

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

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

Hereinafter, embodiments will be described in more detail.

The polyimide film has characteristics of a colored film close to brown in the case of a film having excellent heat resistance, and 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.

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

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

Multi-layer electronic equipment

In order to achieve the above object, the multi-layer electronic device 800 according to an embodiment of the embodiment, the 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, wherein the base layer 100 includes a heat-resistant film 100 to be described below.

The multi-layer electronic device 800 may be a display device.

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

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

The light emitting functional layer 300 includes a color emitting layer (not shown) having an element emitting light according to a signal. Illustratively, the light emitting layer includes a signal transfer layer (not shown) that transmits an external electrical signal to the color emitting layer, and a color emitting layer (not shown) that is disposed on the signal transfer layer and develops a color according to a given signal. , an encapsulation layer (not shown) for protecting the color development layer may be included. The signal transmission layer (not shown) may include a thin film transistor (TFT), for example, LTPS, a-SiTFT, or oxide TFT may be applied, but is not limited thereto. Thin Film Encapsulation (TFE) may be applied to the encapsulation layer (not shown), but is not limited thereto.

The color development layer may be a self-luminescence type color development layer. Exemplarily, quantum dot light-emitting diodes (QLEDs), organic light emitting diodes (OLEDs), or the like may be applied as the color emitting layer, but the present invention is not limited thereto.

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

The light emitting layer 300 may further include a polarization layer (not shown). The polarizing layer may be disposed above or below the chromophoric layer.

The light emitting layer 300 may further include a color filter layer (not shown). The color filter layer may be disposed above or below the color developing 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, or the like, which is 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 a transparent metal layer having a sealing function is preferably applied. 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 this way, when the signal transmission layer under the other surface of the light emitting layer and the electrode layer on one surface of the light emitting layer are provided together, the structure is suitable for applying a light emitting functional layer such as an 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 a laminate including OCA (Optically Clear Adhesive), PSA (Pressure Sensitive Adhesive), or a combination thereof.

A detailed description of the heat-resistant film and the polyimide layer will be omitted since it overlaps with the description below.

If necessary, the multi-layer electronic device may further include an additional boundary layer (not shown) under the base layer, or may be further connected to the support means (or driving means) of the rollable or bendable display.

If necessary, in the multi-layer electronic device, an additional rollable or bendable display driving means (or supporting means) may be further connected on the cover layer.

The driving means or the supporting means can be applied without limitation as long as they are applied to a rollable or bendable display in general.

heat resistant film

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

[Equation 1]

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

The polyimide layer 50 has excellent optical characteristics as well as heat resistance characteristics.

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

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

The polyimide layer 50 may have a coefficient of thermal expansion (ppm/°C) of 60 or less, or 50 or less. The polyimide layer 50 may have a coefficient of thermal expansion (ppm/°C) of 45 or less and 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 value of the thermal expansion coefficient, the heat resistance property is relatively good.

The polyimide layer 50 may have a thickness of 2 to 100 μm, 2 to 55 μm, and more than 2 μm and less than 40 μm. The following optical properties will be described based on a 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 can be seen clearly with the naked eye, and is excellent for application as a base film such as a display.

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

The polyimide layer 50 may have a light transmittance of 85% or more, 88% or more, and 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, and 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 RETS-100 model of OTSUKA Electronics, and taking the in-plane retardation Re value at 550 nm as a standard. The polyimide layer having the 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 expressed 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 a numerical value of in-plane retardation 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, and 7 or less. In this range, the polyimide layer having the optical index can maintain the coefficient of thermal expansion and in-plane retardation, which is difficult to obtain excellent physical properties, at a certain level or more at the same time.

The polyimide layer 50 may have a glass transition temperature of 375 °C or higher, 380 °C or higher, and 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 that of the existing polyimide layer, and the microstructure of the polymer changes due to various influences such as control of viscosity and control of temperature and atmosphere during the manufacturing process such as polymerization and drying process. , it is thought that the glass transition temperature has the above range due to this effect.

The polyimide layer 50 has a constant thickness over the entire area. Specifically, the polyimide layer 50 divides the polyimide layer into 40 regions with a substantially equal area, and the thickness measured at 40 points, 1 point in each area, is the average value of the thicknesses measured at the 40 points. The uniformity of the thickness is excellent within the range of -5 to +5% of the contrast.

The polyimide layer 50 has excellent heat resistance along with 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, the value obtained by subtracting the Td1 from the Td5 may be 65° C. or less, 60° C. or less, and 55° C. or less. In the polyimide layer 50 , the value obtained by subtracting the Td1 from the Td5 may be 25° C. or more. In the polyimide layer 50 , the 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 properties.

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

It includes a polyimide layer 50 having a heat resistance and transparency index (H-T Index) of 8 or more expressed by Equation 3 below.

[Equation 3]

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

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

When the polyimide layer 50 has the above-described heat resistance and transparency index, it is possible to provide a heat resistant film excellent in heat resistance and optical properties, in particular, yellowness.

The polyimide layer 50 includes a polymer formed by polymerization of 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 Ropropane (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 the following Chemical Formula 1-1.

[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), pilomellitic dianhydride (PMDA), and may include any one selected from the group consisting of combinations thereof.

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

[Formula 2-1]

[Formula 2-2]

The aromatic diamine compound and the aromatic dianhydride compound may be reacted 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 Formula 2-1 and the compound of Formula 2-2 are applied together in the above ratio, heat resistance and optical properties can be improved at the same time.

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

The polyimide layer 50 is a 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl residue and hexafluoroisopropylidenediphthalic anhydride residue 1: 0.35 to 0.65 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 including residues in the above ratio is applied to the heat-resistant film, heat resistance and optical properties are simultaneously satisfied, and the efficiency and workability of the process can be improved.

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. For example, a laminate including an optically clear adhesive (OCA), a pressure sensitive adhesive (PSA), or a combination thereof may be applied.

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

The heat-resistant film 100, including the polyimide layer described above, serves as a support layer while satisfying heat-resistance and optical properties at the same time, and thus has excellent utility as a base layer. In addition, when the heat-resistant film is used as a base layer, not only the upper surface of the light emitting functional layer corresponding to the front surface of the multi-layer electronic device but also the base layer corresponding to the back surface can be transparently manufactured, so that foldable, flexible, It has excellent usability for bendable devices, and can provide a reliable heat-resistant film in terms of heat resistance, thickness, insulation characteristics, support characteristics, etc.

Heat-resistant film manufacturing method

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.

The polymer solution preparation step is a step for preparing a polymer solution by stirring a raw material composition including diamine and dianhydride. The polymer solution preparation step 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 aromatic dianhydride compounds.

Since the description of the aromatic diamine compound, the type of the aromatic dianhydride compound, the application ratio, etc. overlaps with the above description, the description thereof will be omitted.

The reaction process is a process in which the raw material composition is stirred in an organic solvent while inducing an imidization reaction. The product in the above reaction process is referred to as a reaction solution for convenience.

The content of solids of the raw material composition under the organic solvent may be 10 to 40% by weight, 15 to 30% by weight, and 18 to 25% by weight. When it has such a solid content, workability is more excellent.

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

The first 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, and the reaction temperature is 1 to 30 ° C. 10 minutes to 10 hours may proceed during the reaction time. Preferably, at a reaction temperature of 1 to 9 °C, 10 minutes to 10 hours may be performed during the reaction time.

The second 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.

Through this process, a reaction solution can be prepared.

The aging process is a process of storing the reaction solution to form a polymer solution having a constant viscosity. The aging process may be a process of storage for 4 to 20 hours at 10 to 35 ℃. The aging process may be a process of storage 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 allows the reaction to proceed slowly after the reaction process, thereby making it easy to obtain a polymer solution having an intended viscosity. In addition, it was experimentally confirmed that differences in physical properties including the glass transition temperature of the formed polyimide layer may occur compared to the case where the aging process was not performed. Through this, it is thought that if the appropriate aging process described above is further performed, it affects the control of the polymer structure of the polyimide layer to be produced, and thus a polyimide layer with better physical properties can be obtained.

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

Additional additives, process stabilizers, etc. may be added to the polymer solution as needed. The additive, the process stabilizer, etc. can 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 the sheet 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 drying time. The drying temperature is exemplarily 100 to 180 ℃, the drying time may be applied to 3 to 60 minutes. The drying may be performed in an inert atmosphere or a vacuum oven in order 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, and 360 to 420 °C. The heating rate to the heat treatment temperature may be 3 to 25 °C/min, 10 to 20 °C/min, and 13 to 17 °C/min. When such heat treatment temperature and temperature increase rate are applied, the degree of polymerization is controlled so as to have the intended physical properties of the film to be produced, and more stable heat treatment can be performed.

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

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

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

Preparation of polyimide layer A

(Example 1)

In a double-jacketed 1L glass reactor with temperature control, 458 g of NMP (N-Methyl-2-Pyrrolidone), an organic solvent, was filled under a nitrogen atmosphere at 40° C., and 2,2'-bis (trifluoromethyl), an aromatic diamine ) -4,4'-diaminobiphenyl (TFDB) 0.170mol was dissolved while slowly added. Then, 0.102 mol of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6-FDA) was slowly added thereto, followed by stirring at 5°C for 3 hours. Then, 0.068 mol of PMDA (Pyromellitic dianhydride) was added, stirred at 50 °C for 4 hours, and then aged at 25 °C for 12 hours. Then, the viscosity at room temperature was measured.

After measuring the viscosity, an additive and a process stabilizer were further added and stirred for 4 hours to obtain a polymer solution. After the polymer solution was applied to 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 a temperature range of 150 °C to 400 °C, and cured in an atmospheric atmosphere (hot air oven) at 400 °C to finally obtain a polyamide film having a thickness of 10 µm, which was It was applied as a mid-layer.

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

In the case of Examples 2 to 3 and Comparative Examples 1 to 2, a polyimide layer was prepared by the manufacturing method of Example 1, but the raw materials were added according to the composition of 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.

In the table below, the values converted based on 100 moles of diamine content are listed.

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
molar ratio* Standard: 6 FDA 0.667 1.000 1.500 0.429 0.250 1.500

* Display up to the 3rd decimal place.

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 following measurement methods, and the results are shown in Table 2 below.

(1) Thickness was measured using a digital micrometer 547-401 of Mitsutoyo, Japan, and the thickness was measured at 10 random positions and the average value was used to measure the thickness. In case of thickness deviation, divide the area into 40 using the above device, select a point from the center of each point, measure the thickness at 40 points, and if the average value is in the range of -5 to +5 % of the total value P, when it is out of the above range, it is indicated as F.

(2) Yellowness (YI) was measured using a CIE colorimetric system of a spectrophotometer (UltraScan PRO, manufactured by Hunter Associates Laboratory). YI was calculated according to ASTM E-313 standard.

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

(4) To measure the viscosity, the temperature of the polymer solution (varnish) was maintained at 25°C, and a viscometer of TOKI SANGYO's BH-II Model was used. RPM was set to 4 and it was confirmed that the target viscosity was realized using spindle number 4

(5) For Td1 and Td5, 2 g of a measurement sample was taken and thermal analysis was performed using Model Q500 of TA's TGA (Thermal Gravimetric Analysis) equipment. The analysis was carried out at a heating rate of 10 °C/min from 25 °C to 700 °C to obtain mass loss data according to temperature. In the analysis, it was assumed that the sample weight at 25°C was 100%, the temperature at which 1% of the weight was reduced was defined as Td1, and the temperature at the time when 5% of the weight was decreased was defined as Td5.

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

* After raising the temperature from 30°C to 350°C (temperature increase rate of 5°C/min or more, 1st heating), it is cooled again to a temperature of 50°C.

* Raise the temperature from 50°C to 450°C (temperature increase rate 5°C/min or higher, 2nd heating).

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

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

[Equation 1]

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

(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 a numerical value of in-plane retardation 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 (℃)
In the air, 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 refers to the viscosity of the polymer solution. Among the evaluation items, the items excluding the viscosity were measured for the film. ND means no measurement.

Referring to Tables 1 and 2, it was reviewed that Comparative Example 3 was not suitable for application to multi-layer electronic equipment for displays because of its high heat resistance-optical index and relatively high yellowness.

In addition, it was confirmed that when the molar ratio of PMDA was less than 0.538 when 6FDA was considered as the standard (1), it was difficult to control the thickness of the film or the heat resistance properties were substantially inferior. That is, in the case of Comparative Examples 1 and 2, the viscosity was low, so that thickness non-uniformity occurred or the heat resistance was somewhat lower than those of the other Examples.

In the case of Examples 1 to 3, although there was a slight difference in kurtosis, it was confirmed that processability suitable for film formation was shown, and both optical 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 it has excellent heat resistance and transparency at the same time even when curing is performed in an atmospheric atmosphere at about 400 °C. At 500 °C, it was confirmed that the optical properties deteriorated rapidly when curing was carried out in an atmospheric atmosphere.

Although 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 by those skilled in the art using the basic concept of the present invention as defined in the following claims are also provided. is within the scope of the

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

Claims (11)

base layer;
a light emitting functional layer disposed on the base layer; and
a cover layer disposed on the light emitting functional layer; and
The base layer includes a heat-resistant film,
The heat-resistant film is heat-resistance represented by Equation 1 below - multilayer electronic equipment comprising a polyimide layer having an optical index (HR Index) of 25 to 150;
[Equation 1]

In Equation 1 above,
Wherein H is the coefficient of thermal expansion (ppm / ℃) value of the polyimide layer,
Y is the yellowness value at 10 μm thickness of the polyimide layer,
R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
According to claim 1,
The polyimide layer has a yellowness of 7 or less, a multilayer electronic device.
According to claim 1,
The polyimide layer has a thickness variation within 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, a multilayer electronic device.
According to claim 1,
The polyimide layer has an optical index (R Index) of 11 or less represented by Equation 2 below, multi-layer electronic equipment;
[Equation 2]

In Equation 2 above,
Y is the yellowness value at 10 μm thickness of the polyimide layer,
R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
Heat resistance represented by Equation 1 below - a heat-resistant film comprising a polyimide layer having an optical index (HR Index) of 25 to 150;
[Equation 1]

In Equation 1 above,
Wherein H is the coefficient of thermal expansion (ppm / ℃) value of the polyimide layer,
Y is the yellowness value at 10 μm thickness of the polyimide layer,
R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
7. The method of claim 6,
A temperature (°C) at which 5 wt% of the polyimide layer is reduced is 550°C or higher, a heat-resistant film;
7. The method of claim 6,
Td5 is the temperature (°C) at which 5 wt% of the polyimide layer is reduced,
Td1 is the temperature (°C) at which 1 wt% of the polyimide layer is reduced,
The value obtained by subtracting the Td1 from the Td5 is 70 ℃ or less, the heat-resistant film.
7. The method of claim 6,
Wherein the polyimide layer comprises a molar ratio of hexafluoroisopropylidenediphthalic anhydride residue and pyromellitic acid anhydride residue in a molar ratio of 1: 0.5 to 1.9.
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;
a sheet manufacturing step of applying the polymer solution in the form of a sheet and then drying the sheet with hot air; and
A film manufacturing step of manufacturing a polyimide film by heat-treating the sheet at 150 to 500 °C; including,
The heat-resistant film includes the polyimide film,
The polyimide film is heat-resisting represented by Equation 1 below - an optical index (HR Index) of 25 to 150, a method of manufacturing a heat-resistant film;
[Equation 1]

In Equation 1 above,
Wherein H is the coefficient of thermal expansion (ppm / ℃) value of the polyimide layer,
Y is the yellowness value at 10 μm thickness of the polyimide layer,
R is an in-plane retardation numerical value at 550 nm based on a 10 μm thickness of the polyimide layer.
11. The method of claim 10,
The polymer solution preparation step includes a reaction process and an aging process,
The reaction process is a process of inducing a reaction in the raw material composition while stirring the raw material composition under an organic solvent to form a reaction solution,
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.

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