KR102819987B1 - Optical film and display apparatus comprising the same - Google Patents

Abstract

One embodiment of the present invention provides an optical film including a light-transmitting substrate and a filler dispersed in the light-transmitting substrate, wherein the filler has a fiber shape and has a driving toughness strain index of 10.5% or less, and a display device including the optical film.

Description

OPTICAL FILM AND DISPLAY APPARATUS COMPRISING THE SAME

The present invention relates to an optical film and a display device including the same, and more particularly, to an optical film having a low ductility deformation index and excellent weather resistance.

Recently, due to the thinning, weight reduction, and flexibility of display devices, the use of optical films instead of glass as cover windows is being considered. In order for an optical film to be used as a cover window of a display device, it is necessary to have excellent optical characteristics as well as excellent mechanical characteristics. For example, the optical film needs to have excellent strength, hardness, wear resistance, and flexibility.

In order to impart desired properties to optical films that require various characteristics, fillers are sometimes added. Fillers can vary depending on the properties required for the optical film.

One embodiment of the present invention is to provide an optical film including a fibrous filler dispersed within a light-transmitting substrate.

Another embodiment of the present invention is to provide an optical film having excellent driving properties by including a fiber-shaped filler dispersed within a light-transmitting substrate.

Another embodiment of the present invention is to provide an optical film having excellent ductility strain index by including a fiber-shaped filler dispersed within a light-transmitting substrate.

Another embodiment of the present invention is to provide an optical film having excellent operating elasticity limit by including a fiber-shaped filler dispersed within a light-transmitting substrate.

Another embodiment of the present invention is to provide a cover window substrate including the optical film.

Another embodiment of the present invention is to provide a display device including the optical film.

An optical film according to one embodiment of the present invention includes a light-transmitting substrate and a filler dispersed in the light-transmitting substrate, wherein the filler has a fiber shape and may have a driving force strain index of 10.5% or less.

Here, the driving force deformation index is calculated according to the following equation 1,

[Formula 1]

The above first driving force is the driving force measured after treatment under room temperature and humidity conditions,

The above room temperature and humidity condition treatment is a condition in which the optical film is left for 1 hour at a temperature of 25℃±3℃ and a humidity of 30%±5%.

The above second driving force is the driving force measured after treatment under high temperature and high humidity conditions.

The above high temperature and high humidity condition treatment is a condition in which the optical film is left for 1 hour at a temperature of 60℃±3℃ and a humidity of 90%±5%.

The above driving force is defined as the product of the area occupied by the section where the strain is 1.6% or less in the strain-stress curve and the specimen length, by measuring the strain for the stress of the optical film using a dynamic mechanical analyzer (DMA), and obtaining a strain-stress curve with the strain of the optical film as the x-axis and the stress as the y-axis.

An optical film according to one embodiment of the present invention can have a first driving toughness of 240 MPa·mm or more.

An optical film according to one embodiment of the present invention can have a second driving toughness of 217 MPa·mm or more.

An optical film according to one embodiment of the present invention may have a first driving elastic limit of 155 MPa·mm or more.

Here, the first driving elastic limit is calculated according to Equation 2 below.

[Formula 2]

1st driving elastic limit = 1st driving toughness / 1st driving toughness strain

The value of the above first driving force strain is 1.6%.

An optical film according to one embodiment of the present invention may have a second driving elastic limit of 140 MPa·mm or more.

Here, the second driving elastic limit is calculated according to Equation 3 below.

[Formula 3]

Second drive elastic limit = Second drive toughness / Second drive toughness strain

The value of the above second driving force strain is 1.6%.

According to one embodiment of the present invention, the filler may include at least one of glass fiber, aluminum-based fiber, and fluoride fiber.

The above filler may include at least one of aluminum oxide hydroxide, SiO ₂ , Al ₂ O ₃ , PTFE (Polytetrafluoroethylene), and PVDF (Polyvinylidene Fluoride).

According to one embodiment of the present invention, the light-transmitting substrate can be formed from a polymerizable composition comprising a diamine monomer; and at least one of a dianhydride compound and a dicarbonyl compound.

The above-mentioned light-transmitting substrate may include at least one of an imide repeating unit and an amide repeating unit.

The above diamine monomers are bis trifluoromethyl benzidine (2,2'-bis(trifluoromethyl)benzidine, TFDB), oxydianiline (4,4'-Oxydianiline, ODA), p-phenylene diamine (pPDA), meta-phenylene diamine (mPDA), p-methylene diamine (pMDA), meta-Methylene diamine (mMDA), bis aminophenoxy benzene (1,3-bis(3-aminophenoxy) benzene, 133APB), bis aminophenoxy benzene (1,3-bis(4-aminophenoxy) benzene, 134APB), bis amino phenoxy phenyl hexafluoropropane (2,2'-bis[4(4-aminophenoxy)phenyl] hexafluoropropane, 4BDAF), Bisaminophenyl hexafluoropropane (2,2'-bis(3-aminophenyl)hexafluoropropane, 33-6F), Bisaminophenyl hexafluoropropane (2,2'-bis(4-aminophenyl)hexafluoropropane, 44-6F), Bisaminophenyl sulfone (bis(4-aminophenyl)sulfone, 4DDS), Bisaminophenyl sulfone (bis(3-aminophenyl)sulfone, 3DDS), Cyclohexanediamine (1,3-Cyclohexanediamine, 13CHD), Cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), Bisamino phenoxy phenylpropane (2,2-Bis[4-(4-aminophenoxy)-phenyl]propane, 6HMDA), Bisaminohydroxy phenyl It may include at least one of hexafluoropropane (2,2-Bis(3-amino-4-hydroxy-phenyl)-hexafluoropropane, DBOH), and bisaminophenoxy diphenyl sulfone (4,4'-Bis(3-amino phenoxy) diphenyl sulfone, DBSDA).

The above dianhydride compounds are biphenyl tetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellictic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, pyromellicticacid dianhydride, PMDA), benzophenone tetracarboxylic dianhydride (3,3,4,4-Benzophenone tetracarboxylic dianhydride, BTDA), oxydiphthalic dianhydride (4,4-ODPA), It may include at least one of Bis(3,4dicarboxyphenyl)dimethyl-silane dianhydride (SiDA), Bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), Sulfonyldiphthalic anhydride (SO2DPA), Cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), and Isopropylidenediphenoxy bis phthalic anhydride (4,4'-(4,4'-Isopropylidenediphenoxy) bis(phthalic anhydride, 6HBDA).

The above dicarbonyl compound may include at least one of terephthaloyl chloride (TPC), phthaloyl chloride, isophthaloyl chloride (IPC), 4,4'-Biphenyldicarbonyl chloride (DPDOC), 4,4'-Oxybis(benzoyl chloride, OBBOC), naphthalene-2,3-dicarbonyl dichloride, and cyclohexanedicabonyldichloride (CHDOC).

According to one embodiment of the present invention, the molar ratio of the dianhydride compound and the dicarbonyl compound may be in the range of 5:95 to 40:60.

A cover window substrate according to another embodiment of the present invention may include the optical film.

According to another embodiment of the present invention, a cover window substrate includes a light-transmitting sheet and a coating layer on the light-transmitting sheet, wherein the light-transmitting sheet may include the optical film.

According to another embodiment of the present invention, a cover window substrate may further include a primer layer disposed between the light-transmitting sheet and the coating layer.

Another embodiment of the present invention provides a display device including a display panel and the optical film disposed on the display panel.

According to one embodiment of the present invention, the filler included in the optical film has a fiber shape and can entangle the polymer chains constituting the light-transmitting substrate. As a result, the optical film can have excellent mechanical strength, and in particular, can have excellent driving toughness and driving toughness deformation index.

In addition, according to one embodiment of the present invention, it can have excellent driving elasticity limit and driving elasticity limit index.

According to one embodiment of the present invention, an optical film including a fiber-shaped filler can have excellent mechanical properties in addition to excellent optical properties. The optical film according to one embodiment of the present invention has excellent optical properties and mechanical properties, and can be usefully used as a cover window of a display device.

Figure 1 is a schematic diagram of an optical film according to one embodiment of the present invention.
FIG. 2 is a schematic diagram of a cover window substrate according to another embodiment of the present invention.
FIG. 3 is a schematic diagram of a cover window substrate according to another embodiment of the present invention.
FIG. 4 is a cross-sectional view of a portion of a display device according to another embodiment of the present invention.
Figure 5 is an enlarged cross-sectional view of portion “P” of Figure 4.
Figure 6 is an external view of a display device according to another embodiment of the present invention.
Figure 7 is a strain-stress curve after treatment under room temperature and humidity conditions for Examples 1, 2, and Comparative Example 1.
Figure 8 is a strain-stress curve after treatment under high temperature and high humidity conditions for Examples 1, 2, and Comparative Example 1.
Figure 9 is a strain-stress curve after treatment under room temperature and humidity conditions for Examples 3 and 4 and Comparative Example 2.
Figure 10 is a strain-stress curve after treatment under high temperature and high humidity conditions for Examples 3 and 4 and Comparative Example 2.
Figure 11 is a strain-stress curve after treatment under room temperature and humidity conditions for Examples 5 and 6 and Comparative Example 3.
Figure 12 is a strain-stress curve after treatment under high temperature and high humidity conditions for Examples 5 and 6 and Comparative Example 3.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the embodiments described below are presented for the purpose of illustration only to help a clear understanding of the present invention, and do not limit the scope of the present invention.

The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are exemplary, and the present invention is not limited to the matters illustrated in the drawings. The same components may be referred to by the same reference numerals throughout the specification. In explaining the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

In the present specification, when the terms "includes," "has," and "consists of" are used, other parts may be added unless the expression "only" is used. When a component is expressed in the singular, it includes the plural unless there is a special explicit description. In addition, when interpreting a component, it is interpreted to include a range of errors even if there is no separate explicit description.

When describing a positional relationship, for example, when the positional relationship between two parts is described as 'on', 'above', 'below', 'next to', etc., one or more other parts can be located between the two parts, unless the expression 'right' or 'directly' is used.

The spatially relative terms "below," "beneath," "lower," "above," "upper," and the like can be used to easily describe the relationship of one element or component to another element or component, as illustrated in the drawings. The spatially relative terms should be understood to include different orientations of the elements during use or operation in addition to the orientations depicted in the drawings. For example, if an element illustrated in the drawings is flipped over, an element described as "below" or "beneath" another element may now be located "above" the other element. Thus, the exemplary term "below" can include both the above and below directions. Likewise, the exemplary term "above" or "above" can include both the above and below directions.

When describing a temporal relationship, for example, when describing a temporal relationship such as 'after', 'following', 'next to', or 'before', it can also include cases where there is no continuity, as long as the expression 'right away' or 'directly' is not used.

Although the terms first, second, etc. are used to describe various components, these components are not limited by these terms. These terms are only used to distinguish one component from another. Accordingly, a first component referred to below may also be a second component within the technical concept of the present invention.

The term "at least one" should be understood to include all combinations that can be presented from one or more of the associated items. For example, the meaning of "at least one of the first, second, and third items" can mean not only each of the first, second, or third items, but also all combinations of items that can be presented from two or more of the first, second, and third items.

The individual features of the various embodiments of the present invention may be partially or wholly combined or combined with each other, and may be technically linked and driven in various ways, and each embodiment may be implemented independently of each other or may be implemented together in a related relationship.

Figure 1 is a schematic diagram of an optical film (100) according to one embodiment of the present invention. According to one embodiment of the present invention, a film having light transmittance is called an optical film (100).

An optical film (100) according to one embodiment of the invention includes a light-transmitting substrate (110) and a filler (120) dispersed in the light-transmitting substrate.

The light-transmitting substrate (110) according to one embodiment of the present invention has light-transmitting properties. According to one embodiment of the present invention, the light-transmitting substrate (110) may have flexible properties. For example, the light-transmitting substrate (110) may have bending properties, folding properties, or rollable properties. As a result, the optical film (100) according to one embodiment of the present invention has light-transmitting properties and may have bending properties, folding properties, or rollable properties.

The properties that can be used to verify the reliability of materials with flexible characteristics include mechanical properties such as strength, hardness, strain, and elastic modulus. The mechanical properties of a material indicate the degree of the material's response to external action. For example, it refers to the relationship between external force and the resulting deformation of the material. In order to verify the deformation relationship of the material according to the external force, for example, a universal tensile tester (UTM) or a dynamic mechanical analyzer (DMA) can be used to evaluate the stress relaxation behavior.

According to one embodiment of the present invention, the light-transmitting substrate (110) may include at least one of an imide repeating unit and an amide repeating unit.

The light-transmitting substrate (110) according to one embodiment of the present invention can be manufactured from monomer components including, for example, dianhydride and diamine. Specifically, the light-transmitting substrate (110) can include an imide repeating unit formed by dianhydride and diamine.

However, the light-transmitting substrate (110) according to one embodiment of the present invention is not limited thereto, and the light-transmitting substrate (110) may be manufactured from monomer components including a dicarbonyl compound in addition to dianhydride and diamine. The light-transmitting substrate (110) according to one embodiment of the present invention may have an imide repeating unit and an amide repeating unit. As a light-transmitting substrate (110) having an imide repeating unit and an amide repeating unit, there is, for example, a polyamide-imide resin.

According to one embodiment of the present invention, the light-transmitting substrate (110) may include a polyimide-based polymer. Examples of the polyimide-based polymer include a polyimide polymer, a polyamide-imide polymer, and the like. The light-transmitting substrate (110) according to one embodiment of the present invention may be made of, for example, a polyamide-imide-based polymer resin.

According to one embodiment of the present invention, the light-transmitting substrate (110) can be formed from a polymerizable composition.

A polymerizable composition according to one embodiment of the present invention may include a diamine monomer.

According to one embodiment of the present invention, the diamine monomer is, for example, bis trifluoromethyl benzidine (2,2'-bis(trifluoromethyl)benzidine, TFDB), oxydianiline (4,4'-Oxydianiline, ODA), para-phenylene diamine (pPDA), meta-phenylene diamine (mPDA), para-Methylene Diamine (pMDA), meta-Methylene Diamine (mMDA), bis aminophenoxy benzene (1,3-bis(3-aminophenoxy) benzene, 133APB), bis aminophenoxy benzene (1,3-bis(4-aminophenoxy) benzene, 134APB), bis amino phenoxy phenyl hexafluoropropane (2,2'-bis[4(4-aminophenoxy)phenyl] hexafluoropropane (4BDAF), bis-aminophenyl hexafluoropropane (2,2'-bis(3-aminophenyl)hexafluoropropane, 33-6F), bis-aminophenyl hexafluoropropane (2,2'-bis(4-aminophenyl)hexafluoropropane, 44-6F), bis-aminophenyl sulfone (4DDS), bis-aminophenyl sulfone (3DDS), cyclohexanediamine (1,3-Cyclohexanediamine, 13CHD), cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), bis-amino phenoxy phenylpropane (2,2-Bis[4-(4-aminophenoxy)-phenyl]propane, 6HMDA), bis-aminohydroxy phenyl It may include at least one of hexafluoropropane (2,2-Bis(3-amino-4-hydroxy-phenyl)-hexafluoropropane, DBOH), bisaminophenoxy diphenyl sulfone (4,4'-Bis(3-amino phenoxy) diphenyl sulfone, DBSDA), but is not limited thereto.

A polymerizable composition according to one embodiment of the present invention may include at least one of a dianhydride compound and a dicarbonyl compound.

According to one embodiment of the present invention, the dianhydride compound is, for example, biphenyl tetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride (BPDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellictic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, pyromellicticacid dianhydride (PMDA), benzophenone tetracarboxylic dianhydride (3,3,4,4-Benzophenone tetracarboxylic dianhydride (BTDA), 4,4-Oxydiphthalic The composition may include at least one of: dianhydride (ODPA), bis(3,4dicarboxyphenyl)dimethyl-silane dianhydride (SiDA), bis dicarboxyphenoxy diphenyl sulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), and isopropylidenediphenoxy bis phthalic anhydride (4,4'-(4,4'-Isopropylidenediphenoxy) bis(phthalic anhydride, 6HBDA). However, the composition is not limited thereto.

According to one embodiment of the present invention, the dicarbonyl compound may include at least one of, for example, Terephthaloyl Chloride (TPC), Phthaloyl Chloride, Isophthaloyl Chloride (IPC), 4,4'-Biphenyldicarbonyl Chloride (DPDOC), 4,4'-Oxybis(benzoyl Chloride (OBBOC), Naphthalene-2,3-dicarbonyl dichloride, and 1,4-Cyclohexanedicabonyldichloride (CHDOC). However, the present invention is not limited thereto.

According to one embodiment of the present invention, the total equivalents of the dianhydride compound and the dicarbonyl compound and the equivalents of the diamine monomer can be substantially the same.

A polymerizable composition according to one embodiment of the present invention may include a dicarbonyl compound in an amount of 60 mol% or more relative to the total number of moles of dianhydride compounds and dicarbonyl compounds to secure excellent mechanical properties.

For example, the molar ratio of the dianhydride compound and the dicarbonyl compound may be in the range of 5:95 to 40:60.

According to one embodiment of the present invention, the filler (120) may have a fiber shape. For example, a fiber may mean a material whose length is significantly longer than its diameter. A fiber may mean a material in the shape of a thin and long thread. A fiber may mean a material having a linear structure. A fiber may also mean a material that is long and bendable.

Hereinafter, a shape having a length greater than the diameter is called a fiber shape. The fiber shape may also be called a filament shape. According to one embodiment of the present invention, the length of the filler (120) may be at least twice greater than the diameter.

According to one embodiment of the present invention, the filler (120) has a fiber shape and can intertwine the polymer chains constituting the light-transmitting substrate (110). As a result, the stability and arrangement characteristics of the polymer chains are improved, so that the mechanical properties of the light-transmitting substrate (110) can be improved, and the mechanical properties of the optical film (100) can also be improved.

There is no particular limitation on the type of filler (120). If it has a fiber shape, it can be used as a filler (120) according to one embodiment of the present invention without limitation on its type. The filler (120) may be an inorganic or organic substance. The filler (120) may include at least one of an inorganic fiber, an organic fiber, and an organic-inorganic composite fiber.

More specifically, the filler (120) may have a fiber shape. For example, the filler (120) may have a single-strand fiber shape, a multi-strand fiber shape, or a shape in which multiple strands are arranged in a branch form around one central strand.

According to one embodiment of the present invention, the filler (120) may include at least one of glass fiber, aluminum-based fiber, and fluoride fiber.

The glass fibers may include SiO ₂ . The glass fibers may further include other components in addition to SiO ₂ . The aluminum-based fibers may include aluminum oxide hydroxide or Al ₂ O ₃ . The aluminum-based fibers may further include other components in addition to aluminum oxide hydroxide or Al ₂ O ₃ . The fluorine fibers may include at least one of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF). The fluorine fibers may further include other components in addition to PTFE and PVDF.

According to one embodiment of the present invention, the filler (120) may include at least one of aluminum oxide hydroxide, SiO ₂ , Al ₂ O ₃ , PTFE (Polytetrafluoroethylene), and PVDF (Polyvinylidene Fluoride).

According to one embodiment of the present invention, the filler (120) may be surface-treated. For example, a fiber surface-treated with an organic compound group having an alkoxy group may be used as the filler (120).

According to one embodiment of the present invention, the aluminum-based fiber may include either aluminum oxide hydroxide or Al ₂ O ₃ . Aluminum oxide hydroxide is also called Boehmite and may be represented by γ-AlO(OH). More specifically, aluminum oxide hydroxide may include a structure represented by any one of the following chemical formulas 1, 2, and 3.

[Chemical Formula 1]

[Chemical formula 2]

[Chemical Formula 3]

Here, n is in the range of 50 to 10,000, m is in the range of 50 to 10,000, and p is in the range of 100 to 20,000.

To help understand the structure of the filler (120), if the structures of chemical formulas 1, 2 and 3 are expanded, the filler (120) may include a structure represented by any one of the following chemical formulas 4, 5 and 6.

The structure represented by Chemical Formula 1 can be represented, for example, by Chemical Formula 4 below. Chemical Formula 4 below corresponds to the case where n is 5 in Chemical Formula 1.

[Chemical Formula 4]

The structure represented by chemical formula 2 can be represented, for example, by chemical formula 5 below. Chemical formula 5 below corresponds to the case where m is 4 in chemical formula 2.

[Chemical Formula 5]

The structure represented by chemical formula 3 can be represented, for example, by chemical formula 6 below. Chemical formula 6 below corresponds to the case where p is 3 in chemical formula 3.

[Chemical formula 6]

In the above chemical formulas 4 to 6, “*” indicates a bonding position.

According to one embodiment of the present invention, Al ₂ O ₃ may have a unit structure represented by the following chemical formula 7.

[Chemical formula 7]

According to one embodiment of the present invention, SiO ₂ may have a unit structure represented by the following chemical formula 8.

[Chemical formula 8]

According to one embodiment of the present invention, the filler (120) may have a diameter of 2 nm to 10 nm and a length of 200 nm to 4,000 nm.

According to one embodiment of the present invention, the diameter and length of the filler (120) can be measured by a transmission electron microscope (TEM).

When the diameter of the filler (120) is less than 2 nm, the stability of the filler (120) may be reduced, and the filler (120) may be broken or crumbled, thereby contaminating the optical film (100), thereby increasing the haze of the optical film (100). When the diameter of the filler (120) exceeds 10 nm, it may be difficult for the filler (120) to have a fiber shape, or the function of intertwining polymer chains may be reduced, and the light transmittance of the optical film (100) may be reduced.

When the length of the filler (120) is less than 200 nm, the function of the filler (120) to link the polymer chains may not be sufficiently exerted. When the length of the filler (120) exceeds 4,000 nm, the dispersibility of the filler (120) may be reduced, and as a result, aggregation of the filler (120) may occur within the light-transmitting matrix (110). Accordingly, the light transmittance of the optical film (100) may be reduced, haze may be increased, and the optical properties of the optical film (100) may be deteriorated.

According to one embodiment of the present invention, the length of the filler (120) can be controlled by the growth conditions of the filler (120) or the post-processing of the filler (120). For example, the length of the filler (120) can be appropriately controlled by controlling the temperature during the growth of the filler (120). In addition, ultrasonic waves or other energy can be applied to the filler (120) grown to a certain length so that the filler (120) can be cut to an appropriate length.

According to one embodiment of the present invention, when a filler (120) is added, appropriate light scattering occurs by the filler (120), so that the optical properties of the optical film (100) can be improved.

According to one embodiment of the present invention, when filler (120) is added, a synergistic effect of tensile properties can be obtained by the filler (120). As a result, a greater force is required to elongate the optical film (100) to the same length. Accordingly, the mechanical properties of the optical film (100) can be improved.

However, if the content of filler (120) is excessive, the yield point of the optical film (100) may be lowered, and the elasticity of the optical film (100) may be insufficient. If the content of filler (120) is trace, the improvement in the mechanical properties of the optical film (100) may be minimal.

Therefore, in order to obtain appropriate strength and elasticity of the optical film (100), the content of the filler (120) included in the optical film (100) can be adjusted to an appropriate range.

For example, the filler (120) may be introduced at 2 to 20 wt% of the polymerizable composition solid content. Specifically, the filler (120) may be introduced at 3 to 15 wt% of the polymerizable composition solid content. More specifically, the filler (120) may be introduced at 3 to 10 wt% of the polymerizable composition solid content.

According to one embodiment of the present invention, by adjusting the content of the filler (120) and improving the dispersion method, the mechanical properties of the optical film (100) can be improved. For example, the driving toughness and elastic limit of the optical film (100) can be improved. In addition, the mechanical properties of the optical film (100) can hardly be deteriorated even after treatment under high temperature and high humidity conditions. Therefore, by adjusting the content of the filler (120) and improving the dispersion method, the mechanical properties of the optical film (100) as well as the weather resistance and long-term stability can be improved.

An optical film (100) according to one embodiment of the present invention can have excellent driving properties.

The driving toughness can be defined as the product of the area of the elastic region in the strain-stress curve and the length (mm) of the optical film (100) specimen. For example, a large driving toughness indicates that the elastic region is wide and the force required to deform the specimen until plastic deformation occurs is large. The optical film (100) specimen can be manufactured to have, for example, a length (L) x width (W) x thickness (T) of 5 mm x 2 mm x 0.05 mm. The unit of the driving toughness is defined as MPa·mm.

In the strain-stress curve, the part where the stress increases steadily as the strain increases and the slope is almost constant corresponds to the elastic region, and the deformation of the material within this section corresponds to elastic deformation. However, the section where the slope and the shape of the curve change abruptly corresponds to the plastic region, and it can be seen that plastic deformation begins to occur as dislocations occur in the internal structure of the material.

Fig. 6 is an external view of a display device (600) according to another embodiment of the present invention. More specifically, Fig. 6 is a schematic side view of a folded state of a foldable display device.

According to FIG. 6, a display device (600) according to another embodiment of the present invention may include an optical film (100) and a case (601) according to an embodiment of the present invention. The display device (600) may be a device that can be bent or folded, such as a foldable display device. In addition, R represents a radius of curvature.

As shown in FIG. 6, when a display device (600) including an optical film (100) according to one embodiment of the present invention is folded, the optical film (100) may be bent by a radius of curvature (R) of 1.5 mm based on a thickness of, for example, 50 μm. In addition, a space (701) may be formed between the bent optical films (100).

When the optical film (100) according to one embodiment of the present invention is bent by a radius of curvature (R) of 1.5 mm based on a thickness of 50 ㎛, the strain (%) of the outermost part of the optical film (100) is 1.6%. Therefore, the driving toughness of the optical film (100) can be obtained based on the strain of 1.6% of the outermost part of the optical film (100).

More specifically, the driving force is defined as the product of the area occupied by the section where the strain is 1.6% or less in the strain-stress curve and the specimen length, by measuring the strain in response to the stress of the optical film (100) using a dynamic mechanical analyzer (DMA), and obtaining a strain-stress curve with the strain of the optical film (100) as the x-axis and the stress as the y-axis.

According to another embodiment of the present invention, the optical film (100) is placed on a display device (600) and can be used under various environmental conditions for a long period of time. When the optical film (100) is repeatedly folded and unfolded under various environmental conditions, deformation may occur. In order to prevent such deformation, elasticity maintenance under deformation or stress conditions is required.

In order to evaluate the elasticity retention ability of the optical film (100), the driving toughness retention ability of the optical film (100) after being subjected to harsh conditions, for example, high temperature and high humidity conditions, can be evaluated.

According to one embodiment of the present invention, an optical film (100) can be manufactured so that the difference in driving toughness after room temperature and humidity condition treatment and the driving toughness after high temperature and high humidity treatment is small.

An optical film (100) according to one embodiment of the present invention can have a first driving toughness of 240 MPa·mm or more.

The above first driving force refers to the driving force measured after treatment under room temperature and humidity conditions.

The above room temperature and humidity condition treatment means the condition of leaving the optical film (100) at a temperature of 25°C±3°C and a humidity of 30%±5% for 1 hour.

When the first driving force is less than 240 MPa·mm, the optical film (100) may not be able to resist external force well under room temperature and humidity conditions, resulting in deformation. For example, when used as a cover window for a foldable device, the folded portion may become deformed when repeatedly folded and unfolded for a long period of time, resulting in reduced visibility. In addition, when subjected to an external force such as pressing, even a weak stimulus with a pencil hardness of 1H may easily leave a mark, and may not be restored over time.

An optical film (100) according to one embodiment of the present invention can have a second driving toughness of 217 MPa·mm or more.

The above second driving force refers to the driving force measured after treatment under high temperature and high humidity conditions.

The above high temperature and high humidity condition treatment means the condition of leaving the optical film for 1 hour at a temperature of 60℃±3℃ and a humidity of 90%±5%.

When the second driving force is less than 217 MPa·mm, the optical film (100) may not be able to resist external force well under high temperature and high humidity conditions, and deformation may occur. For example, when used as a cover window for a foldable device, if the device is folded and unfolded repeatedly while the temperature of the device is high due to watching high-definition video, etc., deformation may occur at the folded portion, resulting in reduced visibility.

An optical film (100) according to one embodiment of the present invention may have a driving toughness strain index of 10.5% or less.

The above-mentioned driving toughness deformation index indicates how much the driving toughness (second driving toughness) of the optical film changes after high-temperature and high-humidity treatment compared to the driving toughness (first driving toughness) of the optical film after room-temperature and high-humidity treatment. For example, a small driving toughness deformation index indicates that the mechanical properties of the optical film are excellent at high temperature and high humidity.

The above driving force deformation index is calculated according to Equation 1 below. The unit of the driving force deformation index is defined as %.

[Formula 1]

If the driving force strain index exceeds 10.5%, the stress decreases significantly as temperature and humidity increase, so it may be difficult to apply it to a foldable device.

An optical film (100) according to one embodiment of the present invention may have a first driving elastic limit of 155 MPa·mm or more.

The above driving elastic limit is the force required for 1% deformation by dividing the force required until the material undergoes a certain deformation by the strain. For example, a large driving elastic limit can be seen as indicating excellent film toughness or strength. The unit of the driving elastic limit is defined as MPa·mm.

The above first driving elastic limit is calculated according to Equation 2 below.

[Formula 2]

1st driving elastic limit = 1st driving toughness / 1st driving toughness strain

The above first driving force strain is 1.6%. The reason why it is limited to 1.6% is because it means the strain of the outermost part of the film when the radius of curvature (R) of a 50㎛ thick film is 1.5 mm.

When the first driving elastic limit is less than 155 MPa·mm, it can be seen that the optical film (100) is easily deformed due to low resistance to external force.

An optical film (100) according to one embodiment of the present invention may have a second driving elastic limit of 140 MPa·mm or more.

The above second driving elastic limit is calculated according to Equation 3 below.

[Formula 3]

Second drive elastic limit = Second drive toughness / Second drive toughness strain

The above second driving force strain is 1.6%. The reason why it is limited to 1.6% is because it means the strain of the outermost part of the film when the radius of curvature (R) of a 50㎛ thick film is 1.5 mm.

When the second driving elastic limit is less than 140 MPa·mm, it can be seen that the optical film (100) is easily deformed by external force at high temperature and high humidity.

An optical film (100) according to one embodiment of the present invention may have a modulus of 7.5 GPa or more.

The modulus of an optical film (100) according to one embodiment of the present invention can be measured by preparing an optical film sample of 10 mm x 100 mm in size and then using a universal tensile tester according to the ASTM D885 method. For example, MODEL 5967 of Instron can be used as the universal tensile tester.

In general, it is known that a film made of a polymer resin has difficulty having a modulus of 6.0 GPa or more. However, according to one embodiment of the present invention, the filler (120) has a fiber shape and can intertwine the polymer chains constituting the light-transmitting matrix (110). As a result, the stability and arrangement characteristics of the polymer chains are improved and the intermolecular force increases, so that the optical film (100) can have a large modulus of 7.5 GPa or more.

More specifically, the optical film (100) according to one embodiment of the present invention may have a modulus of 8.0 GPa or more, and may also have a modulus of 9.0 GPa or more.

The light-transmitting substrate (110) according to one embodiment of the present invention may have a thickness sufficient for the optical film (100) to protect the display panel. For example, the light-transmitting substrate (110) may have a thickness of 10 to 100 μm. The thickness of the light-transmitting substrate (110) may be the same as the thickness of the optical film (100).

FIG. 2 is a schematic diagram of a cover window substrate (200) according to another embodiment of the present invention.

A cover window substrate (200) according to another embodiment of the present invention may include an optical film (100) according to an embodiment of the present invention.

A cover window substrate (200) according to another embodiment of the present invention may further include a coating layer (130) on the light-transmitting sheet to enhance the surface properties of the light-transmitting sheet and the cover window substrate (200). The light-transmitting sheet may include an optical film (100) according to one embodiment of the present invention.

FIG. 3 is a schematic diagram of a cover window substrate (300) according to another embodiment of the present invention.

According to another embodiment of the present invention, a cover window substrate (300) may further include a primer layer (140) disposed between the light-transmitting sheet and the coating layer (130) to improve adhesion between the light-transmitting sheet and the coating layer (130).

Hereinafter, with reference to FIGS. 4 and 5, a display device (400) using an optical film (100) according to one embodiment of the present invention will be described.

FIG. 4 is a cross-sectional view of a portion of a display device (400) according to another embodiment of the present invention, and FIG. 5 is an enlarged cross-sectional view of a portion “P” of FIG. 4.

Referring to FIG. 4, a display device (400) according to another embodiment of the present invention includes a display panel (501) and an optical film (100) on the display panel (501).

Referring to FIGS. 4 and 5, the display panel (501) includes a substrate (510), a thin film transistor (TFT) on the substrate (510), and an organic light-emitting element (570) connected to the thin film transistor (TFT). The organic light-emitting element (570) includes a first electrode (571), an organic light-emitting layer (572) on the first electrode (571), and a second electrode (573) on the organic light-emitting layer (572). The display device (400) disclosed in FIGS. 4 and 5 is, for example, an organic light-emitting display device.

The substrate (510) may be made of glass or plastic. Specifically, the substrate (510) may be made of plastic such as a polyimide-based resin or an optical film. Although not shown, a buffer layer may be disposed on the substrate (510).

A thin film transistor (TFT) is disposed on a substrate (510). The thin film transistor (TFT) includes a semiconductor layer (520), a gate electrode (530) that is insulated from the semiconductor layer (520) and overlaps at least a portion of the semiconductor layer (520), a source electrode (541) connected to the semiconductor layer (520), and a drain electrode (542) that is spaced apart from the source electrode (541) and connected to the semiconductor layer (520).

Referring to FIG. 5, a gate insulating film (535) is disposed between a gate electrode (530) and a semiconductor layer (520). An interlayer insulating film (551) may be disposed on the gate electrode (530), and a source electrode (541) and a drain electrode (542) may be disposed on the interlayer insulating film (551).

A planarizing film (552) is placed on a thin film transistor (TFT) to planarize the upper portion of the thin film transistor (TFT).

The first electrode (571) is placed on the planarization film (552). The first electrode (571) is connected to a thin film transistor (TFT) through a contact hole provided in the planarization film (552).

The bank layer (580) is arranged on a portion of the first electrode (571) and the planarizing film (552) to define a pixel area or a light-emitting area. For example, the bank layer (580) may be arranged in a matrix structure in a boundary area between a plurality of pixels, thereby defining a pixel area by the bank layer (580).

The organic light-emitting layer (572) is disposed on the first electrode (571). The organic light-emitting layer (572) may also be disposed on the bank layer (580). The organic light-emitting layer (572) may include one light-emitting layer, or may include two light-emitting layers that are stacked one above the other. The organic light-emitting layer (572) may emit light having one of red, green, and blue colors, and may also emit white light.

The second electrode (573) is placed on the organic light-emitting layer (572).

An organic light-emitting element (270) can be formed by stacking a first electrode (571), an organic light-emitting layer (572), and a second electrode (573).

Although not shown, when the organic light-emitting layer (572) emits white light, each pixel may include a color filter for filtering the white light emitted from the organic light-emitting layer (572) by wavelength. The color filter is formed on the path of light.

A thin film encapsulation layer (590) may be placed on the second electrode (573). The thin film encapsulation layer (590) may include at least one organic film and at least one inorganic film, and at least one organic film and at least one inorganic film may be placed alternately.

An optical film (100) according to one embodiment of the present invention may be placed on a display panel (501) having the laminated structure described above. The optical film (100) may include a light-transmitting matrix (110) and a filler (120) dispersed in the light-transmitting matrix (110).

In addition, a cover window substrate (200, 300) may be placed on a display panel (501) having the laminated structure described above. The cover window substrate (200, 300) may include an optical film (100) according to one embodiment of the present invention.

Hereinafter, a method for manufacturing an optical film (100) according to one embodiment of the present invention will be described.

A method for manufacturing an optical film (100) according to one embodiment of the present invention may include a step of first dispersing a filler (120) in a polymerizable composition for forming a light-transmitting substrate (110) to prepare a first mixture solution and a step of casting the first mixture solution to prepare a cast film.

According to one embodiment of the present invention, a polyimide-based resin solution can be used as a polymerizable composition for forming a light-transmitting substrate (110).

More specifically, a method for manufacturing an optical film (100) according to one embodiment of the present invention may include a step of manufacturing a polyimide-based resin powder, a step of dissolving the polyimide-based resin powder in a first solvent to manufacture a polyimide-based resin solution, a step of dispersing a filler (120) in a second solvent to manufacture a filler dispersion, and a step of mixing the filler dispersion and the polyimide-based resin solution to manufacture a first mixture.

DMAc (N,N-Dimethylacetamide) may be used as the first solvent. DMAc (N,N-Dimethylacetamide) or methyl ethyl ketone (MEK) may be used as the second solvent. However, one embodiment of the present invention is not limited thereto, and other solvents known as the first solvent and the second solvent may be used.

A fiber-shaped filler (120), for example, a fiber-shaped filler (120) having a large aspect ratio, may have a long length relative to its diameter, and thus may easily become entangled or clumped within the light-transmitting matrix. Accordingly, the filler (120) requires excellent dispersibility within the first mixture.

According to one embodiment of the present invention, for example, toluene sulfonic acid (PTSA) may be used as an additive to improve the dispersibility of the filler (120). However, one embodiment of the present invention is not limited thereto, and other known additives may be used to improve the dispersibility of the filler (120).

According to one embodiment of the present invention, in order to improve the dispersibility of the filler (120), the pH of the first mixed solution may be adjusted. For example, the pH of the first mixed solution may be adjusted to a range of 5 to 7. Accordingly, the agglomeration or clumping phenomenon of the filler (120) may be prevented.

Next, the first mixture solution can be cast, dried, and heat-treated to form an optical film (100). According to one embodiment of the present invention, a film formed by casting the first mixture solution can be referred to as a cast film, and a film manufactured by drying and heat-treating the cast film can be referred to as an optical film (100). The cast film can be referred to as an uncured film.

To improve the orientation of the filler (120), casting can be performed by bar coating.

According to one embodiment of the present invention, the direction and degree of orientation of the filler (120) can be changed by controlling the pressure applied to the cast film formed by casting.

In addition, convection can be prevented during the drying and heat treatment process of the cast film formed by casting, thereby allowing the filler (120) to be oriented in a certain direction.

Specifically, when drying the cast film using heat, if convection occurs inside, the orientation of the filler (120) may be reduced. Therefore, the cast film may be dried slowly to prevent convection. For example, drying of the cast film may be performed while the temperature is increased at a rate of 1°C/1 minute (1 degree/1 minute) from 80°C to 120°C. When the drying is performed to a certain level or higher, the orientation of the filler (120) may be fixed.

Hereinafter, the present invention will be described more specifically with reference to exemplary manufacturing examples and examples. However, the present invention is not limited to the manufacturing examples or examples described below.

<Manufacturing Example: Production of Solid Content of Polyimide-Based Polymerizable Composition>

In a 4-chamber double-jacket reactor, 320.23 g of bistrifluoromethyl benzidine (TFDB) was dissolved in dimethylacetamide (DMAc). Then, 79.44 g of biphenyl tetracarboxylic dianhydride (BPDA) was added, and the reaction was carried out by stirring for 2 hours while maintaining the temperature of the reactor at 25°C. When the reaction was complete, 53.31 g of 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) was added, and the reaction was carried out by stirring for 1 hour while maintaining the temperature of the reactor at 25°C.

Afterwards, the temperature of the reactor was lowered to 7℃ or lower, and 118.77g of terephthaloyl chloride (TPC) and propylene oxide (PO) were added. The temperature of the reactor was maintained at 7℃ and stirred for 1 hour, then the temperature was raised to room temperature and left for 24 hours.

After the polymerization reaction was completed, 67.87 g of pyridine and 87.62 g of acetic anhydride were added to the obtained polymer solution, the temperature was raised to 80°C, and the mixture was stirred for 1 hour. The mixture was cooled to room temperature again, and 20 L of methanol was added to the obtained polymerizable composition solution to precipitate a solid, and the precipitated solid was filtered and pulverized, washed again with 2 L of methanol, and then dried in a vacuum at 100°C for 6 hours to obtain a solid of a polyimide-based polymerizable composition in a powder state. The solid content of the polyimide-based polymerizable composition manufactured here is the solid content of the polyamide-imide polymerizable composition. The yield was 80% or more.

<Example 1>

A circulator was connected to maintain the temperature of the four-hole double-jacket reactor at 5°C while maintaining a nitrogen atmosphere, and then 525.17 g of DMAc (first solvent) and 5 parts by weight of filler (120) were filled into the reactor, with a total weight of 100 parts by weight of the polyimide-based resin powder introduced, and stirred for a certain period of time. Thereafter, 85.97 g of the solid powder of the polyimide-based polymerizable composition manufactured in the manufacturing example was introduced, and stirred until dissolved, to prepare a liquid polyimide-based resin solution. Here, the filler (120) is a fibrous alumina hydrate including a structure of chemical formula 1.

When the pH is measured immediately after preparing the liquid polyimide resin solution, the pH is 8 or higher. In order to improve the arrangement characteristics of the filler (120), a weak acid such as acetic acid is added to the liquid polyimide resin solution to adjust the pH of the liquid polyimide resin solution to a range of 5 to 7. The liquid polyimide resin solution prepared in this manner is a polyimide resin solution in which a fiber-shaped filler (120) is dispersed.

The obtained polyimide resin solution was cast. A casting substrate is used for casting. There is no particular limitation on the type of the casting substrate. A glass substrate, a stainless steel (SUS) substrate, a Teflon substrate, etc. can be used as the casting substrate. According to one embodiment of the present invention, an organic substrate can be used as the casting substrate.

Specifically, the obtained polyimide-based resin solution was applied to a glass substrate and casted. In order to improve the orientation of the filler (120), the polyimide-based resin solution was applied to a substrate (organic substrate), and then casted while pressing with a force of 30 N or more in a direction perpendicular to the glass substrate. As a result, a cast film was manufactured.

In order to maintain the orientation of the filler (120) during the drying process of the cast film, the film was manufactured by placing it in a hot air oven at 80°C and slowly drying it at a rate of 1°C/min to 120°C for about 40 minutes, and the manufactured film was peeled off from the glass substrate and fixed to a frame with pins.

The frame with the film fixed thereto was placed in a vacuum oven and slowly heated from 100°C to 280°C for 2 hours, then slowly cooled and separated from the frame to obtain an optical film. The optical film was then heat-treated at 250°C for 5 minutes.

As a result, a 50 ㎛ thick optical film (100) including a light-transmitting substrate (110) and an alumina-based filler (120) dispersed in the light-transmitting substrate was completed.

<Examples 2 to 8>

According to the conditions of Table 1, optical films (100) were manufactured in the same manner as in Example 1 and were referred to as Examples 2 to 8, respectively.

<Comparative examples 1 to 3>

According to the conditions of Table 1, optical films (100) were manufactured in the same manner as Example 1 except for the addition of filler, and these were designated as Comparative Examples 1 to 3, respectively.

division Diamine Monomer Dianhydride
compound Dicarbonyl
compound Types of fillers Filler's
Content TFDB BPDA CBDA 6FDA TPC Example 1 100 27 - 12 61 Alumina hydrate
(chemical formula 1) 5 Example 2 100 27 - 12 61 Alumina hydrate
(chemical formula 1) 10 Example 3 100 - 17 17 66 Alumina hydrate
(chemical formula 1) 7 Example 4 100 - 17 17 66 Alumina Hydrate
(chemical formula 1) 10 Example 5 100 - 26.25 12.5 61.25 Alumina hydrate
(chemical formula 1) 3 Example 6 100 - 26.25 12.5 61.25 Alumina Hydrate
(chemical formula 1) 5 Example 7 100 27 - 12 61 Alumina hydrate
(chemical formula 2) 5 Example 8 100 27 - 12 61 Alumina hydrate
(chemical formula 3) 5 Comparative Example 1 100 27 - 12 61 No added - Comparative Example 2 100 - 17 17 66 No added - Comparative Example 3 100 - 26.25 12.5 61.25 No added

Alumina hydrate (chemical formula 1, 2, 3) filler: 4 nm in diameter and 1500 nm in length

<Measurement method>

The following measurements were performed on the optical films manufactured according to Examples 1 to 8 and Comparative Examples 1 to 3. In addition, the strain-stress curves of Examples 1 to 6 and Comparative Examples 1 to 3 are shown in FIGS. 7 to 12.

(1) Measurement of strain-stress curve

The strain-stress curves of the optical films manufactured according to Examples 1 to 8 and Comparative Examples 1 to 3 were measured using a Dynamic Mechanical Analysis (DMA) model DMA850 from TA instrument.

- Connect RH Chamber (thermo-hygrostat) to control measurement environment

- Measurement specimen: Length (L) x Width (W) x Thickness (T) = 5mm x 2mm x 0.05mm

- Room temperature and humidity condition treatment: Conditions for leaving the optical film specimen at a temperature of 25℃±3℃ and a humidity of 30%±5% for 1 hour

- High temperature and high humidity condition treatment: Conditions for leaving the optical film specimen for 1 hour at a temperature of 60℃±3℃ and a humidity of 90%±5%

- Each specimen of the optical film manufactured according to Examples 1 to 8 and Comparative Examples 1 to 3 was placed on a film tension clamp and measured using the strain sweep method during the Oscillation Test.

(2) Measurement of the surrender point

In the strain-stress curve of the optical film measured in (1) above, the point at which the stress pattern changes abruptly was designated as the yield point. Specifically, the point at which the stress begins to decrease or remain constant even when the strain increases was designated as the yield point. The unit of the yield point is defined as %.

- 1st yield point: Yield point on the strain-stress curve after treatment under room temperature and humidity conditions

- Second yield point: Yield point on the strain-stress curve after treatment under high temperature and high humidity conditions

(3) Measurement of first driving force and second driving force

Based on the strain-stress curve measured in (1) above, when the strain is 1.6%, the area of the strain-stress curve was calculated three times, and the average value multiplied by the length of the specimen was used as the driving toughness. The unit of the driving toughness is defined as MPa·mm.

The first driving toughness is the area obtained based on a strain of 1.6% in the strain-stress curve obtained after treatment under room temperature and humidity conditions, and the second driving toughness is the area obtained based on a strain of 1.6% in the strain-stress curve obtained after treatment under high temperature and high humidity conditions.

(4) Calculation of driving force deformation index

The degree of deformation of the driving toughness according to temperature and humidity changes of the optical films manufactured according to Examples 1 to 8 and Comparative Examples 1 to 3 was defined as the driving toughness deformation index, and was calculated according to Equation 1 below. The unit of the driving toughness deformation index is defined as %.

[Formula 1]

(5) Measurement of the first driving elastic limit and the second driving elastic limit

In the strain-stress curve measured in the above (1), when the strain is 1.6%, the area of the strain-stress curve was taken as the driving toughness, and the value obtained by dividing it by the driving toughness strain was taken as the driving elastic limit, and its value was calculated. The first and second driving toughness strains are 1.6%. The reason for limiting it to 1.6% is because it means the strain of the outermost film when the radius of curvature of a 50 ㎛ thick film is 1.5R.

The above value was calculated three times and the average value was used as the driving elastic limit. The unit of the driving elastic limit is defined as MPa·mm.

The first driving elastic limit and the second driving elastic limit were calculated according to Equations 2 and 3 below.

[Formula 2]

1st driving elastic limit = 1st driving toughness / 1st driving toughness strain

The first driving elastic limit was measured after the optical film specimen was treated under room temperature and humidity conditions.

[Formula 3]

Second drive elastic limit = Second drive toughness / Second drive toughness strain

The second driving elastic limit was measured after treating the optical film specimens under high temperature and high humidity conditions.

(6) Modulus measurement

According to the ASTM D885 method, the modulus of each optical film manufactured according to Examples 1 to 8 and Comparative Examples 1 to 3 was measured using a universal tensile testing machine (MODEL 5967) from Instron.

- Road Cell 30KN, Grip 250N.

- Specimen size 10mm X 100mm, tensile speed 25mm/min

- Since orientation occurs in the direction of coating, the coating direction is called MD, and the direction orthogonal to the coating is called TD, and the modulus in the MD direction of the optical film is measured.

- Modulus Unit: GPa

The results of the physical property measurements are shown in Table 2 below.

division 1st
yield point 2nd
yield point 1st
Drive
tenacity 2nd
Drive
tenacity Driving force
Transformation index 1st drive
Elastic limit Second drive
Elastic limit Modulus
(GPa) Example 1 2.52 2.95 255 242 5.3 160 151 8.0 Example 2 1.86 2.69 333 319 4.1 208 199 9.3 Example 3 1.74 2.11 418 376 10.0 261 235 8.4 Example 4 1.31 1.71 459 424 7.7 287 265 9.3 Example 5 1.61 1.96 371 332 10.4 232 208 7.5 Example 6 1.09 1.36 451 418 7.2 282 261 8.4 Example 7 2.41 2.52 232 244 5.4 145 153 7.8 Example 8 2.74 2.69 233 239 2.7 145 149 10.0 Comparative Example 1 3.14 3.94 239 93.5 60.9 150 58.4 5.9 Comparative Example 2 2.45 2.24 370 294 20.5 232 184 6.0 Comparative Example 3 1.80 2.41 330 284 14.1 206 177 6.5

As disclosed in the measurement results in Table 2, it can be confirmed that the optical film (100) according to the embodiment of the present invention has excellent mechanical properties, such as excellent driving toughness, excellent driving toughness strain index, excellent driving elastic limit, and excellent driving elastic limit index.

100: Optical film 110: Light-transmitting substrate
120: Filler 130: Coating layer
140: Primer layer 200, 300: Cover window substrate
400, 600: Display device 501: Display panel

Claims (17)

a light-transmitting substrate; and
A filler dispersed in the above light-transmitting substrate;
The above filler has a fiber shape,
Optical films having a driving force strain index of 10.5% or less:
Here, the driving force deformation index is calculated according to the following equation 1,
[Formula 1]

The above first driving force is the driving force measured after treatment under room temperature and humidity conditions,
The above room temperature and humidity condition treatment is a condition in which the optical film is left for 1 hour at a temperature of 25℃±3℃ and a humidity of 30%±5%.
The above second driving force is the driving force measured after treatment under high temperature and high humidity conditions.
The above high temperature and high humidity condition treatment is a condition in which the optical film is left for 1 hour at a temperature of 60℃±3℃ and a humidity of 90%±5%.
The above driving force is defined as the product of the area occupied by the section where the strain is 1.6% or less in the strain-stress curve and the specimen length, by measuring the strain for the stress of the optical film using a dynamic mechanical analyzer (DMA), and obtaining a strain-stress curve with the strain of the optical film as the x-axis and the stress as the y-axis. In the first paragraph,
An optical film having a first driving force of 240 MPa·mm or more. In the first paragraph,
An optical film having a second driving toughness of 217 MPa·mm or more. In the second paragraph,
An optical film having a first driving elastic limit of 155 MPa·mm or more:
Here, the first driving elastic limit is calculated according to the following equation 2,
[Formula 2]
1st driving elastic limit = 1st driving toughness / 1st driving toughness strain
The value of the above first driving force strain is 1.6%. In the third paragraph,
An optical film having a second driving elastic limit of 140 MPa·mm or more:
Here, the second driving elastic limit is calculated according to the following equation 3,
[Formula 3]
Second drive elastic limit = Second drive toughness / Second drive toughness strain
The value of the above second driving force strain is 1.6%. In the first paragraph,
An optical film wherein the filler comprises at least one of glass fiber, aluminum-based fiber, and fluoride fiber. In the first paragraph,
An optical film, wherein the filler comprises at least one of aluminum oxide hydroxide, SiO ₂ , Al ₂ O ₃ , PTFE (Polytetrafluoroethylene), and PVDF (Polyvinylidene Fluoride). In the first paragraph,
The above light-transmitting substrate
diamine monomer; and
At least one of a dianhydride compound and a dicarbonyl compound;
An optical film formed from a polymerizable composition comprising: In Article 8,
An optical film, wherein the light-transmitting substrate comprises at least one of an imide repeating unit and an amide repeating unit. In Article 8,
The above diamine monomers are bis trifluoromethyl benzidine (2,2'-bis(trifluoromethyl)benzidine, TFDB), oxydianiline (4,4'-Oxydianiline, ODA), p-phenylene diamine (pPDA), meta-phenylene diamine (mPDA), p-methylene diamine (pMDA), meta-Methylene diamine (mMDA), bis aminophenoxy benzene (1,3-bis(3-aminophenoxy) benzene, 133APB), bis aminophenoxy benzene (1,3-bis(4-aminophenoxy) benzene, 134APB), bis amino phenoxy phenyl hexafluoropropane (2,2'-bis[4(4-aminophenoxy)phenyl] hexafluoropropane, 4BDAF), Bisaminophenyl hexafluoropropane (2,2'-bis(3-aminophenyl)hexafluoropropane, 33-6F), Bisaminophenyl hexafluoropropane (2,2'-bis(4-aminophenyl)hexafluoropropane, 44-6F), Bisaminophenyl sulfone (bis(4-aminophenyl)sulfone, 4DDS), Bisaminophenyl sulfone (bis(3-aminophenyl)sulfone, 3DDS), Cyclohexanediamine (1,3-Cyclohexanediamine, 13CHD), Cyclohexanediamine (1,4-Cyclohexanediamine, 14CHD), Bisamino phenoxy phenylpropane (2,2-Bis[4-(4-aminophenoxy)-phenyl]propane, 6HMDA), Bisaminohydroxy phenyl An optical film comprising at least one of hexafluoropropane (2,2-Bis(3-amino-4-hydroxy-phenyl)-hexafluoropropane, DBOH) and bisaminophenoxy diphenyl sulfone (4,4'-Bis(3-amino phenoxy) diphenyl sulfone, DBSDA). In Article 8,
The above dianhydride compounds are biphenyl tetracarboxylic dianhydride (3,3,4,4-Biphenyltetracarboxylic dianhydride, BPDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride (TDA), pyromellictic acid dianhydride (1,2,4,5-benzene tetracarboxylic dianhydride, pyromellicticacid dianhydride, PMDA), benzophenone tetracarboxylic dianhydride (3,3,4,4-Benzophenone tetracarboxylic dianhydride, BTDA), oxydiphthalic dianhydride (4,4-ODPA), An optical film comprising at least one of bis(3,4dicarboxyphenyl)dimethyl-silane dianhydride (SiDA), 4,4-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride (BDSDA), sulfonyldiphthalic anhydride (SO2DPA), cyclobutane-1,2,3,4-tetracarboxylic dianhydride (CBDA), and 4,4'-(4,4'-Isopropylidenediphenoxy) bis(phthalic anhydride, 6HBDA). In Article 8,
An optical film, wherein the dicarbonyl compound comprises at least one of terephthaloyl chloride (TPC), phthaloyl chloride, isophthaloyl chloride (IPC), 4,4'-Biphenyldicarbonyl chloride (DPDOC), 4,4'-Oxybis(benzoyl chloride, OBBOC), naphthalene-2,3-dicarbonyl dichloride, and cyclohexanedicabonyldichloride (CHDOC). In Article 8,
An optical film, wherein the molar ratio of the dianhydride compound and the dicarbonyl compound is in the range of 5:95 to 40:60. An optical film comprising any one of claims 1 to 13;
Cover window substrate. Light-transmitting sheet; and
A coating layer on the above light-transmitting sheet;
The above light-transmitting sheet comprises an optical film according to any one of claims 1 to 13;
Cover window substrate. In Article 15,
Further comprising a primer layer disposed between the light-transmitting sheet and the coating layer.
Cover window substrate. display panel; and
An optical film according to any one of claims 1 to 13, disposed on the display panel;
A display device including:

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