CN117616072A - Optical film having excellent folding property and display device including the same - Google Patents

Optical film having excellent folding property and display device including the same Download PDF

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Publication number
CN117616072A
CN117616072A CN202180100358.XA CN202180100358A CN117616072A CN 117616072 A CN117616072 A CN 117616072A CN 202180100358 A CN202180100358 A CN 202180100358A CN 117616072 A CN117616072 A CN 117616072A
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optical film
repeating unit
compound
diamine compound
present disclosure
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郑鹤基
朴晓准
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Kolon Industries Inc
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Kolon Industries Inc
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Priority claimed from KR1020210186219A external-priority patent/KR20230011842A/en
Application filed by Kolon Industries Inc filed Critical Kolon Industries Inc
Priority claimed from PCT/KR2021/019823 external-priority patent/WO2023286954A1/en
Publication of CN117616072A publication Critical patent/CN117616072A/en
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Abstract

The invention provides: an optical film comprising a polymer resin and having a yellowness index of 3.0 or less and a folding property parameter of 1.5GPa or less; and a display device including the optical film.

Description

Optical film having excellent folding property and display device including the same
Technical Field
The present disclosure relates to an optical film including a polymer resin having an excellent post-folding recovery force and a display device including the optical film.
Background
Recently, for the purpose of reducing the thickness and weight of the display device and increasing the flexibility thereof, it has been considered to use an optical film instead of glass as a cover window of the display device. In order for the optical film to be able to be used as a cover window for a display device, the optical film is required to have excellent optical and mechanical properties and excellent recovery force after folding.
Therefore, it is necessary to develop a film exhibiting excellent optical properties as well as excellent mechanical properties such as insolubility, chemical resistance, heat resistance, radiation resistance, low temperature characteristics and recovery after folding.
Among the optical films, polyimide (PI) based resins have excellent insolubility, chemical resistance, heat resistance, radiation resistance, and low temperature characteristics, and are used as automobile materials, aviation materials, spacecraft materials, insulating coatings, insulating films, protective films, and the like.
Recently, polyamide-imide-based resins having amide repeating units added thereto have been developed, and films prepared using the polyamide-imide-based resins have excellent optical properties and excellent mechanical properties such as excellent insolubility, chemical resistance, heat resistance, radiation resistance and low temperature characteristics, and recovery after folding.
The amide repeating units may be prepared by polymerization of diamines and dicarbonyl compounds. However, for example, when 2,2' -bis (trifluoromethyl) benzidine (TFDB) is used as the diamine, there is a problem in that the polymerization reaction is insufficient due to gelation of the dicarbonyl compound during polymerization of TFDB and the dicarbonyl compound due to the rigid structure of TFDB.
Therefore, there is a need to develop a polyamide-imide resin having a high polymerization degree even when dicarbonyl compounds are added.
Disclosure of Invention
Technical problem
An aspect of the present disclosure is to provide an optical film including a polymer resin having excellent post-folding recovery force.
Another aspect of the present disclosure is to provide an optical film that exhibits excellent optical and mechanical properties.
Technical proposal
In accordance with the present disclosure, the above and other objects can be accomplished by the provision of an optical film comprising a polymer resin and having a yellowness index of 3.0 or less, and a post-folding recovery force parameter calculated using the following equation 1 of 1.5Gpa or less:
[ equation 1]
Where R is 0.5mm, which is the radius of curvature of the optical film on the folding centerline when folded, d is the thickness of the optical film, which is expressed as μm, and E' is the elastic strain index calculated using the following equation 2, wherein only values (excluding units) are applied to the radius of curvature and the thickness in equation 1.
[ equation 2]
Elastic strain index (E')=e/(1-v) 2 )
Where E is the modulus of the optical film, expressed as GPa, and v is the Poisson's ratio of the optical film.
The elastic strain index (E') calculated using equation 2 may be 5.5 or more.
The polymer resin may comprise imide repeating units and amide repeating units.
The amide repeating units may be present in an amount of 80% or more of the total number of imide repeating units and amide repeating units.
The imide repeating unit may comprise a first repeating unit and a second repeating unit.
The amide repeat unit may comprise a third repeat unit and a fourth repeat unit.
The first repeating unit may be an imide repeating unit formed by polymerization of a first diamine compound and a first dianhydride compound, and the second repeating unit may be an imide repeating unit formed by polymerization of a second diamine compound and a second dianhydride compound.
The third repeating unit may be an amide repeating unit formed by polymerization of the first diamine compound and the first dicarbonyl compound, and the fourth repeating unit may be an amide repeating unit formed by polymerization of the second diamine compound and the second dicarbonyl compound.
The first diamine compound may be 2,2' -bis (trifluoromethyl) benzidine (TFDB).
The second diamine-based compound may contain at least one functional group selected from sulfonyl, carbonyl, methylene, propylene, and halogen.
The second diamine-based compound may include at least one selected from the group consisting of bis (3-aminophenyl) sulfone (3 DDS), bis (4-aminophenyl) sulfone (4 DDS), 2-bis (3-aminophenyl) hexafluoropropane (3, 3' -6F), 2-bis (4-aminophenyl) hexafluoropropane (4, 4' -6F), 4' -Methylenedianiline (MDA), 3' -diaminobenzophenone, 4' -diaminobenzophenone, and benzidine tetrachloride (CIBZ).
The molar ratio of the polymerized first diamine compound to the polymerized second diamine compound may be 95:5 to 50:50.
The weight average molecular weight (Mw) of the polymer resin may be 200,000 to 500,000.
According to another aspect of the present disclosure, there is provided a display device including a display panel and an optical film according to the present disclosure disposed on the display panel.
Advantageous effects
One embodiment of the present disclosure provides an optical film including a polymer resin having excellent post-folding recovery force.
The optical film according to another embodiment of the present disclosure exhibits excellent optical and mechanical properties, and thus, can effectively protect a display surface of a display device when used as a cover window of the display device.
Drawings
FIG. 1 is a cross-sectional view of an optical film showing the change in length when folded;
fig. 2 is a cross-sectional view illustrating a portion of a display device according to one embodiment of the present disclosure;
fig. 3 is an enlarged cross-sectional view showing "P" of fig. 2.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. However, the following embodiments are provided for clarity of understanding only, and do not limit the scope of the present disclosure.
The shapes, dimensions, proportions, angles and values disclosed in the drawings describing embodiments of the present disclosure are merely examples, and the present disclosure is not limited to the detailed description shown. Throughout the specification, like reference numerals refer to like elements. In the following description, when a detailed description of related known functions or configurations is determined to unnecessarily obscure the gist of the present disclosure, the detailed description will be omitted.
In the case where terms such as "comprising," "having," or "including" are used in this specification, other parts may also be present unless "only" is used. Unless stated to the contrary, singular terms may include the plural meaning. In addition, when an element is explained, the element is understood as including an error range even if it is not explicitly described.
In describing the positional relationship, for example, when the positional relationship is described as "upper", "above", "lower" or "next", unless "just" or "direct" is used, a case where there is no contact between them may be included.
Spatially relative terms, such as "lower," "upper," and "upper," may be used herein to describe one device or element's relationship to another device or element as illustrated in the figures. It will be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in one figure is turned over, elements described as "under" or "beneath" another element would then be oriented "over" the other element. Thus, the exemplary terms "under" or "beneath" can include both the meaning of "under" and "above. In the same manner, the exemplary terms "above" or "upper" can include both the meaning of "above" and "below.
In describing the temporal relationship, for example, when "after", "subsequent", "next", or "preceding" are used to describe the temporal sequence, unless "just" or "direct" is used, the case of a discontinuous relationship may be included.
It will be understood that, although the terms "first," "second," etc. may be used herein to describe various elements, these elements are not limited by these terms. These terms are only used to distinguish one element from another element. Accordingly, in the technical idea of the present disclosure, the first element may be referred to as a second element.
It should be understood that the term "at least one" includes all combinations related to one or more. For example, "at least one of the first element, the second element, and the third element" may include all combinations of two or more elements selected from the first, second, and third elements, and each of the first, second, and third elements.
Features of various embodiments of the present disclosure may be combined or combined with each other, either partially or fully, and may be interoperated and technically driven with each other. Embodiments of the present disclosure may be performed independently of each other or may be performed together in a related manner.
One embodiment of the present disclosure provides an optical film. An optical film according to one embodiment of the present disclosure comprises a polymer resin.
The polymer resin may be contained in the film in any of a variety of shapes and forms, for example, as a solid powder, in a state of being dissolved in a solution, or as a matrix that is cured after being dissolved in a solution. Any resin may be considered to be the same as the polymer resin of the present disclosure, regardless of its shape and form, as long as it is a resin comprising the same repeating units as in the present disclosure. Typically, the polymer resin may be present in the film in the form of a matrix, which is obtained by coating a polymer resin solution and drying it to form a solid.
According to one embodiment of the present disclosure, the post-folding recovery force parameter of the optical film calculated using the following equation 1 is 1.5GPa or less:
[ equation 1]
Where R is 0.5mm, which is the radius of curvature of the optical film on the fold centerline when folded, d is the thickness of the optical film, expressed as μm, E' is the elastic strain index calculated using equation 2 below, where the thickness of the optical film can be measured using an electronic micrometer, for example, from Anritsu Corporation, the radius of curvature of the optical film is measured by determining the gap between the folded inner folded portions using a gap gauge in a bending tester, for example, DLDM111LHA from YUASA, and in equation 1, only the values (excluding units) are applied to the radius of curvature and thickness.
[ equation 2]
Elastic strain index (E')=e/(1-v) 2 )
Where E is the modulus of the optical film, expressed as GPa, and v is the Poisson's ratio of the optical film.
The modulus of the optical film can be measured using a universal tester (e.g., from Instron corp.) under the following conditions according to ASTM D882 standard.
-25℃/50RH％
-a load cell: 30KN, clamp: 250N.
Sample size: 10X 50mm, stretching speed: 25mm/min
Poisson's ratio of an optical film is the ratio of transverse strain to axial strain of a specimen subjected to an axial load and can be measured using a non-contact (video extensometer) method according to ASTM E-132 standard. Specifically, poisson's ratio can be measured using a universal tester (e.g., instron 3367 from Instron corp. Inc.).
Test speed: 10mm/min
-(25±2)℃/(45±5)％RH
The post-folding restoring force parameter of the present disclosure will be described in more detail with reference to the accompanying drawings. Fig. 1 is a cross-sectional view of an optical film, showing the change in length when the optical film is folded. Fig. 1 shows only one example for showing the length change when the optical film is folded, and the length change when folded may be different for each optical film. Accordingly, the present disclosure is not limited thereto.
When the post-folding recovery force parameter of the optical film is 1.5GPa or less, the resistance generated at the time of folding is reduced, whereby an excellent post-folding recovery force can be obtained and no folding mark is formed. As the radius of curvature (R) decreases, the occurrence of fold marks increases. When the post-folding recovery force parameter is 1.5GPa or less, the post-folding recovery force is excellent, and therefore, no folding trace occurs. In particular, the radius of curvature (R) in the post-folding restoring force parameter is 0.5mm. When the post-folding recovery force parameter is 1.5GPa or less and the radius of curvature (R) is 0.5mm, no folding trace is formed and an excellent post-folding recovery force can be obtained.
Specifically, when the optical film is folded, mechanical changes occur in the film. As used herein, the term "fold mark" refers, for example, to a phenomenon in which a film bends, has a non-uniform wrinkled surface, or, in the case of a transparent film, produces a white haze. In addition, in addition to the occurrence of wrinkles or haze, changes in the length of the optical film, as well as changes in the mechanical and optical properties of the optical film, such as changes in light transmittance, can occur before and after folding.
When the optical film is folded, stress is applied to the film. At this time, compressive stress is applied to the folded inner surface (hereinafter referred to as "inner diameter") of the optical film in the folding direction, and tensile stress is applied to the outer surface (hereinafter referred to as "outer diameter") thereof, which is the surface opposite thereto. Thus, compressive strain occurs in the inner diameter of the optical film and tensile strain occurs in the outer diameter of the optical film.
Specifically, as shown in fig. 1, the distance between two points (a and b) on the inner diameter of the fold is equal to the distance between two points (c, d) on the outer diameter of the fold prior to the fold. However, when the optical film is folded, two points a and b on the inner diameter of the optical film are converted into a 'and b' by compressive stress during folding, and two points c and d on the outer diameter are converted into c 'and d' by tensile stress during folding. The distance between a 'and b' becomes shorter than the distance between a and b due to the compressive stress on the inner diameter of the fold, and the distance between c 'and d' on the outer diameter of the fold becomes longer than the distance between c and d. At this time, the radius of curvature (R1) of the inner diameter of the fold is "R-d/2" based on the center line (M) of the optical film, and the radius of curvature (R2) of the outer diameter of the fold is "R+d/2" based on the center line (M) of the optical film. Distance L between a 'and b' calculated based on the radius of curvature of the folded inner and outer diameters 1 And the distance L between c' and d 2 Pi (R-d/2) and pi (R+d/2), respectively.
Compressive and tensile stresses are proportional to the magnitude of the length change. The length change of the outer diameter is +pi (d/2), and the length change of the inner diameter is-pi (d/2). Thus, the stress applied to the inner diameter is proportional to d/2R (= [ pi (d/2) ]/pi R), and the stress applied to the outer diameter is proportional to d/2R. As the stress applied to the outer diameter and the inner diameter decreases, the restoring force of the optical film after folding increases. Thus, a lower value of d/2R for the optical film facilitates folding. Specifically, when d/2R is 0.08 or less, the optical film exhibits excellent post-folding recovery, and thus leaves no folding trace, and when d/2R exceeds 0.08, excessive pressure is applied during folding, and folding traces are left after folding.
In addition, the post-folding recovery force parameter of the optical film is proportional to the elastic strain index (E'). As the elastic strain index (E ') increases, the post-folding recovery force of the optical film increases, and as the elastic strain index (E') decreases, the post-folding recovery force of the optical film deteriorates.
According to one embodiment of the present disclosure, the elastic strain index (E') of the optical film calculated using equation 2 may be 5.5GPa or more. By controlling the thickness and radius of curvature of the optical film, and its modulus and poisson's ratio, the post-folding recovery of the optical film can be improved. As the modulus and poisson's ratio of the optical film increase, the strain (deformation) resistance of the optical film increases during folding. For example, even if the thickness of the optical film increases, the restoring force after folding increases as the modulus of the optical film increases. On the other hand, even if the thickness of the optical film is reduced, when the modulus of the optical film is also reduced, the restoring force after folding is deteriorated, making the optical film unsuitable for use as a cover window of a flexible display device. Further, if the poisson's ratio of the optical film increases, the post-folding recovery force increases, and conversely, when the poisson's ratio of the optical film decreases, the post-folding recovery force deteriorates.
According to one embodiment of the present disclosure, the yellowness index (y.i.) of the optical film may be 3.0 or less. The yellowness index can be measured according to ASTM E313 standard using a spectrophotometer (CM-3700D,KONICA MINOLTA).
According to one embodiment of the present disclosure, the optical film may include a polymer resin.
By controlling the composition and content of the repeating units of the polymer resin, a post-folding resilience parameter of 1.5GPa or less can be imparted to the optical film. In addition, by increasing the polymerization degree of the polymer resin, the post-folding recovery force parameter can be reduced and the post-folding recovery force can be improved.
The polymer resin may include at least one of an imide repeating unit and an amide repeating unit. For example, the polymer resin may contain one of an imide repeating unit or an amide repeating unit, and may contain both an imide repeating unit and an amide repeating unit. The polymer resin may include at least one of polyimide-based resin, polyamide-based resin, and polyamide-imide-based resin.
In the present disclosure, the imide repeating units of the polymer resin may be prepared from monomer components including diamine-based compounds and dianhydride-based compounds. The diamine compound and dianhydride compound may polymerize to form an amic acid, and the amic acid may be imidized again to form imide repeating units. In addition, the amide repeating unit may be prepared by polymerization of monomer components including a diamine compound and a dicarbonyl compound. The specific structure of the imide repeating unit and the amide repeating unit may vary depending on the monomers used for polymerization.
However, the polymer resin according to one embodiment of the present disclosure is not limited thereto. The polymer resin according to one embodiment of the present disclosure may be prepared from a monomer component further comprising other compounds in addition to the diamine-based compound, the dianhydride-based compound, and the dicarbonyl-based compound. Thus, a polymer resin according to one embodiment of the present disclosure may contain other repeating units in addition to the imide repeating units and the amide repeating units.
The optical film according to one embodiment of the present disclosure may include at least one of a polyimide-based resin, a polyamide-based resin, and a polyamide-imide-based resin.
According to one embodiment of the present disclosure, the optical film may be any one of a polyimide-based film, a polyamide-based film, and a polyamide-imide-based film, but the embodiment of the present disclosure is not limited thereto. Any film having light transmittance may be used as the optical film according to one embodiment of the present disclosure.
In one embodiment of the present disclosure, the polymer resin may include an amide repeating unit in an amount corresponding to 80% or more of the total number of imide repeating units and amide repeating units. Preferably, the polymer resin may contain the amide repeating units in an amount corresponding to 95% or more, more preferably 98% or more of the total number of the imide repeating units and the amide repeating units.
When the polymer resin contains the amide repeating unit in an amount corresponding to 80% or more of the total number of the imide repeating unit and the amide repeating unit, the optical properties of the film made of the polymer resin can be maintained while the mechanical properties can be improved; in particular, the restoring force after folding can be greatly improved. That is, an optical film containing an amide repeating unit in an amount larger than that of an imide repeating unit, which is colorless and transparent and has excellent insolubility, chemical resistance, heat resistance, radiation resistance, low temperature characteristics, recovery after folding, and the like, can be produced.
When a large amount of dicarbonyl compound is added in order to form a large amount of amide repeating units, there is a problem in that the polymerization degree of the resin is lowered because the dicarbonyl compound gels and thus the polymerization reaction does not proceed sufficiently.
In the present disclosure, gelation of dicarbonyl compounds may be prevented or inhibited by polymerization using two or more different types of diamine compounds.
According to one embodiment of the present disclosure, the imide repeating unit may comprise a first repeating unit and a second repeating unit.
The imide repeating unit is formed by polymerization of a diamine compound and a dianhydride compound, the first repeating unit is an imide repeating unit obtained by polymerization of a first diamine compound and a first dianhydride compound, and the second repeating unit is an imide repeating unit obtained by polymerization of a second diamine compound and a second dianhydride compound. The polymer resins of the present disclosure comprise repeat units from at least two types of diamine-based compounds, including a first diamine-based compound and a second diamine-based compound.
Specifically, according to one embodiment of the present disclosure, the first diamine compound is 2,2' -bis (trifluoromethyl) benzidine (TFDB). According to one embodiment of the present disclosure, the second diamine-based compound includes an aromatic diamine-based compound other than TFDB. The imide repeat units and amide repeat units of the present disclosure may be from TFDB and aromatic diamines other than TFDB.
Since 2,2' -bis (trifluoromethyl) benzidine (TFDB) has a specific linear and rigid structure, it is possible to impart greatly improved mechanical properties such as insolubility, chemical resistance, heat resistance, radiation resistance and low temperature characteristics to a film comprising a repeating unit derived from TFDB.
However, due to the rigid structure of 2,2' -bis (trifluoromethyl) benzidine (TFDB), the polymerization between TFDB and dicarbonyl compounds is accelerated. This rapid polymerization may react only a portion of the dicarbonyl compound with the diamine compound, and the remaining portion of the dicarbonyl compound may gel without being polymerized. Gelation of dicarbonyl-based compounds reduces the degree of polymerization of the resin and deteriorates the optical properties of the film. Thus, it is difficult to prepare a polymer resin containing a large amount of amide repeating units only by adding 2,2' -bis (trifluoromethyl) benzidine (TFDB). According to the present disclosure, the second diamine-based compound can prevent gelation of the dicarbonyl-based compound and improve the polymerization degree of the polymer.
According to one embodiment of the present disclosure, the second diamine-based compound comprises an aromatic diamine-based compound.
In one embodiment of the present disclosure, the term "aromatic diamine compound" refers to a diamine compound in which an amino group is directly bound to an aromatic ring, and may include an aliphatic group or other substituent as part of its structure. The aromatic ring may be a single ring, a fused ring including a single ring directly attached thereto via a heteroatom, or a fused ring. Examples of the aromatic ring may include, but are not limited to, benzene ring, biphenyl ring, naphthalene ring, anthracene ring, and fluorene ring.
According to one embodiment of the present disclosure, the second diamine-based compound may be represented by the following chemical formula 1:
[ chemical formula 1]
H 2 N-A 1 -NH 2
Wherein A is 1 Represents a divalent aromatic organic group. An aromatic organic group refers to an organic group in which pi electrons are delocalized, whereby single bonds and double bonds are alternately connected to each other to form a ring. For example, A 1 May include divalent aromatic organic radicals having 4 to 40 carbon atomsA bolus. The hydrogen atom in the aromatic organic group in chemical formula 1 may be substituted with a halogen element, a hydrocarbon group, or a hydrocarbon group substituted with a halogen element. Here, the hydrocarbon group or the hydrocarbon group substituted with a halogen element may have 1 to 8 carbon atoms. For example, A 1 Hydrogen in (C) may be replaced by-F, -CH 3 、-CF 3 And the like.
An optical film manufactured using a diamine-based compound in which a hydrogen atom is substituted with a hydrocarbon group substituted with fluorine can be given excellent light transmittance and excellent processability.
A in chemical formula 1 1 A structure represented by any one of the following chemical formulas may be included, for example.
In the above chemical formula, the binding site is represented. In the above formula, X may be a single bond, O, S, SO 2 、CO、CH 2 、C(CH 3 ) 2 And C (CF) 3 ) 2 Any one of the following. Although there is no particular limitation on the bonding position of X on each ring, the bonding position of X may be, for example, meta or para on each ring.
According to one embodiment of the present disclosure, the second diamine-based compound may include at least one functional group selected from sulfonyl, carbonyl, methylene, propylene, and halogen.
The function of sulfonyl, carbonyl, methylene, propylene and halogen substituents is to control the movement of electrons in the compound. Thus, the second diamine compound contains at least one substituent selected from the group consisting of sulfonyl, carbonyl, methylene, propylene and halogen, thereby controlling ionization energy. Therefore, the reactivity and the reaction rate of the polymerization reaction with the dicarbonyl-based compound can be appropriately adjusted.
According to one embodiment of the present disclosure, the second diamine-based compound may include at least one selected from the group consisting of bis (3-aminophenyl) sulfone (3 DDS), bis (4-aminophenyl) sulfone (4 DDS), 2-bis (3-aminophenyl) hexafluoropropane (3, 3' -6F), 2-bis (4-aminophenyl) hexafluoropropane (4, 4' -6F), 4' -Methylenedianiline (MDA), 3' - (dimethylamino) benzophenone (3, 3' -CO), 4' - (dimethylamino) benzophenone (4, 4' -CO), and benzidine tetrachloride (CIBZ).
According to one embodiment of the present disclosure, the first dianhydride compound and the second dianhydride compound may each be independently represented by the following chemical formula 2. The first dianhydride compound and the second dianhydride compound may be the same or different from each other. The present disclosure is not limited thereto.
[ chemical formula 2]
In chemical formula 2, A 2 Represents a tetravalent organic group. For example, A 2 May comprise tetravalent organic groups having 4 to 40 carbon atoms. The hydrogen atom in the organic group in chemical formula 2 may be substituted with a halogen element, a hydrocarbon group, or a hydrocarbon group substituted with a halogen element. Here, the hydrocarbon group or the hydrocarbon group substituted with a halogen element may have 1 to 8 carbon atoms.
A in chemical formula 2 2 A structure represented by any one of the following chemical formulas may be included, for example.
In the above chemical formula, the binding site is represented. In the above formula, Z can be independently a single bond, O, S, SO 2 、CO、(CH 2 ) n 、(C(CH 3 ) 2 ) n And (C (CF) 3 ) 2 ) n N may be an integer of 1 to 5. Although there is no particular limitation on the bonding position of Z on each ring, the bonding position of Z may be, for example, meta or para on each ring.
In one embodiment of the present disclosure, the first dianhydride compound and the second dianhydride compoundCan each independently include a compound selected from the group consisting of 2, 2-bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6 FDA), biphenyl tetracarboxylic dianhydride (BPDA), naphthalene Tetracarboxylic Dianhydride (NTDA), diphenylsulfone tetracarboxylic dianhydride (DSDA), 4- (2, 5-oxo-tetrahydrofuran-3-yl) -1,2,3, 4-tetrahydronaphthalene-1, 2-dicarboxylic anhydride (TDA), pyromellitic dianhydride (PMDA), benzophenone Tetracarboxylic Dianhydride (BTDA), oxydiphthalic anhydride (ODPA), bis (carboxyphenyl) dimethylsilane dianhydride (SiDA), bis (dicarboxyphenoxy) diphenyl sulfide dianhydride (BDSDA), sulfonyl diphthalic anhydride (SO) 2 DPA) and isopropylidenediphenoxybis (phthalic anhydride) (BPADA).
An optical film according to one embodiment of the present disclosure may include, for example, a variety of dianhydride-based compounds.
An optical film manufactured using a dianhydride compound in which a hydrogen atom is substituted with a hydrocarbon group substituted with fluorine can exhibit excellent light transmittance and processability.
According to one embodiment of the present disclosure, the amide repeating unit may comprise a third repeating unit and a fourth repeating unit.
The amide repeating unit is formed by polymerization of a diamine compound and a dicarbonyl compound, the third repeating unit is an amide repeating unit obtained by polymerization of a first diamine compound and a first dicarbonyl compound, and the fourth repeating unit is an amide repeating unit obtained by polymerization of a second diamine compound and a second dicarbonyl compound.
According to one embodiment of the present disclosure, the first dicarbonyl compound and the second dicarbonyl compound may each be independently represented by the following chemical formula 3. The first dicarbonyl compound and the second dicarbonyl compound may be the same or different from each other. The present disclosure is not limited thereto.
[ chemical formula 3]
In chemical formula 3, A 3 Represents a divalent organic group. For example, A 3 May comprise a divalent organic group having 4 to 40 carbon atoms. The hydrogen atom in the organic group in chemical formula 3 may be substituted with a halogen element, a hydrocarbon group, or a hydrocarbon group substituted with fluorine. Here, the hydrocarbon group or the hydrocarbon group substituted with fluorine may have 1 to 8 carbon atoms. For example, A 3 Hydrogen in (C) may be replaced by-F, -CH 3 、-CF 3 And the like.
A in chemical formula 3 3 A structure represented by any one of the following chemical formulas may be included, for example.
In the above chemical formula, the binding site is represented. In the above formula, Y may independently be a single bond, O, S, SO 2 、CO、CH 2 、C(CH 3 ) 2 And C (CF) 3 ) 2 Any one of the following. Although there is no particular limitation on the bonding position of Y on each ring, the bonding position of Y may be, for example, meta or para on each ring.
According to one embodiment of the present disclosure, the first dicarbonyl-based compound and the second dicarbonyl-based compound may each independently include at least one selected from terephthaloyl chloride (TPC), isophthaloyl chloride (IPC), biphenyldicarbonyl chloride (BPDC), 4' -oxybisbenzoyl chloride (OBBC), and naphthalenedicarboxylic acid dichloride (NTDC).
In one embodiment of the present disclosure, the ratio of the number of first and third repeating units to the number of second and fourth repeating units is 95:5 to 50:50. Both the first repeating unit and the third repeating unit are repeating units formed by polymerization using the first diamine compound, and both the second repeating unit and the fourth repeating unit are repeating units formed by polymerization using the second diamine compound. Thus, the molar ratio of the first diamine compound for polymerization to the second diamine compound for polymerization is 95:5 to 50:50.
Regarding the ratio of the number of the first and third repeating units to the number of the second and fourth repeating units, when the fraction of the number of the first and third repeating units is increased to 95:5 or more, haze of the film increases due to the increase in the ratio of the repeating units from TFDB and dicarbonyl-based compound. On the other hand, when the fraction of the number of the second and fourth repeating units is increased to 50:50 or more, the heat resistance and strength of the film are deteriorated.
The polymer resin according to one embodiment of the present disclosure may include a first repeating unit represented by the following chemical formula 4 and a second repeating unit represented by the following chemical formula 5:
[ chemical formula 4]
Wherein A is 2 As described in the foregoing description of the invention,
[ chemical formula 5]
Wherein A is 1 And A 2 As described above.
The polymer resin according to one embodiment of the present disclosure may include a third repeating unit represented by the following chemical formula 6 and a fourth repeating unit represented by the following chemical formula 7:
[ chemical formula 6]
Wherein A is 3 As described in the foregoing description of the invention,
[ chemical formula 7]
Wherein A is 1 And A 3 As described above.
According to one embodiment of the present disclosure, the weight average molecular weight (Mw) of the polymer resin of the present disclosure may be 200,000 to 500,000.
The weight average molecular weight of the polymer resin can be measured using GPC (Alliance e2695/2414RID, waters) under the following conditions.
A detector: 2414RID, waters
Mobile phase: liBr in DMAc 10mM
Sample concentration: 0.25 (w/w) percent in DMAc
Column and detector temperature: 50 DEG C
Flow rate: 1.0ml/min
Gelation of dicarbonyl compounds due to high reaction rates with diamine compounds, particularly TFDB, reduces the degree of polymerization of polymer resins containing a large number of amide repeat units. The weight average molecular weight is proportional to the degree of polymerization. That is, as the degree of polymerization decreases, the weight average molecular weight of the polymer resin also decreases.
When the weight average molecular weight of the polymer resin is less than 200,000, the degree of polymerization decreases, the number of terminal groups of the polymer chain increases, and the physical properties of the polymer resin deteriorate. On the other hand, it is difficult to prepare a polymer resin having a weight average molecular weight of more than 500,000 in this process. The weight average molecular weight of the polymer resin is adjusted by controlling the polymerization viscosity during the polymerization. Resins having a weight average molecular weight exceeding 500,000 are disadvantageous in processing because of very high polymerization viscosity and consequent reduced flowability of the reaction solution, which makes control and handling difficult and requires a large amount of solvent for redissolving the polymer resin.
According to one embodiment of the present disclosure, the optical film is light transmissive. In addition, the optical film is flexible. For example, an optical film according to one embodiment of the present disclosure is bendable, foldable, or crimpable. The optical film may have excellent mechanical and optical properties.
According to one embodiment of the present disclosure, the optical film may have a thickness sufficient for the optical film to protect the display panel. For example, the thickness of the optical film may be 10 μm to 100 μm.
According to one embodiment of the present disclosure, the average light transmittance of the optical film in the visible light region measured using an ultraviolet spectrophotometer may be 88% or more based on a thickness of 50 μm.
The average light transmittance of the optical film may be measured in a wavelength range of 360nm to 740nm using a spectrophotometer.
According to one embodiment of the present disclosure, the haze of the optical film may be 0.5% or less based on a thickness of 50 μm.
Haze of the optical film can be determined by cutting the manufactured optical film into samples having a size of 50mm×50mm, measuring 5 times using a haze meter (model name: manufactured by HM-150,Murakami Color Research Laboratory) according to ASTM D1003, and taking an average of 5 values as haze of the optical film.
Fig. 2 is a cross-sectional view showing a part of a display device 200 according to another embodiment, and fig. 3 is an enlarged cross-sectional view of "P" in fig. 2.
Referring to fig. 2, a display device 200 according to another embodiment of the present disclosure includes a display panel 501 and an optical film 100 on the display panel 501.
Referring to fig. 2 and 3, the display panel 501 includes: a substrate 510, a thin film transistor TFT on the substrate 510, and an organic light emitting device 570 connected to the thin film transistor TFT. The organic light emitting device 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 200 shown in fig. 2 and 3 is an organic light emitting display device.
The substrate 510 may be formed of glass or plastic. In particular, the substrate 510 may be formed of a plastic such as a polymer resin or an optical film. Although not shown, a buffer layer may be disposed on the substrate 510.
The thin film transistor TFT is disposed on the substrate 510. The thin film transistor TFT includes a semiconductor layer 520, a gate electrode 530 insulated from the semiconductor layer 520 and at least partially overlapping the semiconductor layer 520, a source electrode 541 connected to the semiconductor layer 520, and a drain electrode 542 spaced apart from the source electrode 541 and connected to the semiconductor layer 520.
Referring to fig. 3, a gate insulating layer 535 is disposed between the gate electrode 530 and the semiconductor layer 520. An interlayer insulating layer 551 may be disposed on the gate electrode 530, and source and drain electrodes 541 and 542 may be disposed on the interlayer insulating layer 551.
A planarization layer 552 is disposed on the thin film transistor TFT to planarize the top of the thin film transistor TFT.
The first electrode 571 is disposed on the planarization layer 552. The first electrode 571 is connected to the thin film transistor TFT through a contact hole provided in the planarizing layer 552.
The bank layer 580 is disposed on the planarization layer 552 in a portion of the first electrode 571 to define a pixel region or a light emitting region. For example, the bank 580 is disposed at a boundary between a plurality of pixels in a matrix form to define a corresponding pixel region.
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 two light emitting layers stacked in a vertical direction. Light having any one of red, green, and blue may be emitted from the organic light emitting layer 572, and white light may be emitted from the organic light emitting layer 572.
The second electrode 573 is disposed on the organic light emitting layer 572.
The first electrode 571, the organic light emitting layer 572, and the second electrode 573 may be stacked to constitute the organic light emitting device 570.
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 based on a specific wavelength. The color filter is formed in the optical path.
A thin film encapsulation layer 590 may be disposed on the second electrode 573. The thin film encapsulation layer 590 may include at least one organic layer and at least one inorganic layer, and the at least one organic layer and the at least one inorganic layer may be alternately disposed.
The optical film 100 is disposed on the display panel 501 having the above-described stacked structure.
Hereinafter, a method of manufacturing an optical film according to another embodiment of the present disclosure will be briefly described.
A method of manufacturing an optical film according to one embodiment of the present disclosure includes: preparing a polymer resin; dissolving a polymer resin in a solvent to prepare a polymer resin solution; and manufacturing an optical film using the polymer resin solution.
The preparation of the polymer resin may be performed by polymerizing monomers forming the polymer resin.
According to another embodiment of the present disclosure, the polymer resin may be prepared from a monomer component including a first diamine compound, a second diamine compound, a first dianhydride compound, a second dianhydride compound, a first dicarbonyl compound, and a second dicarbonyl compound. In the present disclosure, the order or method of addition of the monomers is not limited. For example, the first and second dianhydride-type compounds and the first and second diamine-type compounds may be sequentially added to the solution in which the first and second diamine-type compounds are dissolved, and the resulting mixture may be polymerized. Alternatively, to avoid randomness, the first diamine compound, the first and second dianhydride compounds, the second diamine compound, and the first and second dicarbonyl compounds may be added in this order, or the second diamine compound, the first and second dianhydride compounds, the first diamine compound, and the first and second dicarbonyl compounds may be added in this order, and then polymerized.
More specifically, the polymer resin may be prepared by polymerization and imidization of monomers including a first diamine compound, a second diamine compound, first and second dianhydride compounds, and first and second dicarbonyl compounds. The imide repeating units can be prepared by polymerization and imidization of monomers comprising first and second diamine-based compounds and first and second dianhydride-based compounds. In addition, the amide repeating unit may be prepared by polymerization of monomers including the first and second diamine-based compounds and the first and second dicarbonyl-based compounds.
Thus, a polymer resin according to another embodiment of the present disclosure may have an imide repeating unit and an amide repeating unit.
The imide repeat unit and the amide repeat unit may be prepared separately and then copolymerized. Alternatively, the imide repeating unit may be first prepared, and then the dicarbonyl-based compound may be further added to prepare the amide repeating unit, or the amide repeating unit may be first prepared, and then the dianhydride-based compound may be further added to prepare the imide repeating unit. The polymer resin of the present disclosure is not limited to the formation order of repeating units (order of adding monomers).
According to another embodiment of the present disclosure, the first and second dicarbonyl compounds may be added in an amount of 80 mole% or more based on the total molar amount of the first and second dianhydride compounds and the first and second dicarbonyl compounds. Thus, the polymer resins of the present disclosure comprise amide repeat units in an amount of 80% or more. Preferably, the first and second dicarbonyl compounds may be added in an amount of 95 mole% or more, more preferably 98 mole% or more, based on the total molar amount of the first and second dianhydride compounds and the first and second dicarbonyl compounds.
According to another embodiment of the present disclosure, the first diamine compound is 2,2' -bis (trifluoromethyl) benzidine (TFDB).
According to another embodiment of the present disclosure, the second diamine compound comprises an aromatic diamine compound. Hereinafter, in order to avoid repetitive description, explanation of the above configuration is omitted.
2,2' -bis (trifluoromethyl) benzidine (TFDB) may be used as the first diamine compound, the aromatic diamine compound of the above chemical formula 1 may be used as the second diamine compound, and the compound of the above chemical formula 2 may be used as the first and second dianhydride compounds. The compound of the above chemical formula 3 may be used as the first and second dicarbonyl compounds.
According to another embodiment of the present disclosure, the aromatic diamine-based compound of the second diamine-based compound may include at least one functional group selected from sulfonyl, carbonyl, methylene, propylene, and halogen.
According to another embodiment of the present disclosure, the aromatic diamine compound of the second diamine compound may include at least one selected from the group consisting of bis (3-aminophenyl) sulfone (3 DDS), bis (4-aminophenyl) sulfone (4 DDS), 2-bis (3-aminophenyl) hexafluoropropane (3, 3' -6F), 2-bis (4-aminophenyl) hexafluoropropane (4, 4' -6F), 4' -Methylenedianiline (MDA), 3' - (dimethylamino) benzophenone (3, 3' -CO), 4' - (dimethylamino) benzophenone (4, 4' -CO), and benzidine tetrachloride (CIBZ).
According to another embodiment of the present disclosure, the ratio of the addition amount of the first diamine compound to the addition amount of the second diamine compound may be 95:5 to 50:50.
In another embodiment of the present disclosure, the solvent used to prepare the polymer resin solution may be, for example, a polar aprotic organic solvent such as N, N-dimethylacetamide (DMAc), N-Dimethylformamide (DMF), 1-methyl-2-pyrrolidone (NMP), m-cresol, tetrahydrofuran (THF), chloroform, methyl Ethyl Ketone (MEK), or a mixture thereof. However, the solvent according to one embodiment of the present disclosure is not limited thereto, and other solvents may be used.
Hereinafter, the present disclosure will be described in more detail with reference to exemplary embodiments. However, the following preparations and examples should not be construed as limiting the scope of the present disclosure.
Example 1 ]
While nitrogen was passing through the reactor, 313.34g of N, N-dimethylacetamide (DMAc) was charged into a 500mL reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller, and a cooler. Then, the temperature of the reactor was adjusted to 25 ℃, 24.02g (0.075 mol) of TFDB as the first diamine compound was dissolved therein, 6.21g (0.025 mol) of bis (3-aminophenyl) sulfone (3 DDS) as the second diamine compound was further dissolved therein, and the resulting solution was maintained at 25 ℃. To the resulting diamine compound solution, 0.89g (0.002 mol) of 6FDA was added, and thoroughly dissolved therein by stirring for 2 hours. The reactor temperature was lowered to 10℃and 19.90g (0.098 mol) of terephthaloyl chloride (TPC) was added thereto, completely dissolved, and reacted for 1 hour, and then the temperature was raised to 25 ℃. To the resultant reaction solution, 0.35g of pyridine and 0.45g of acetic anhydride were added, and stirred at 80℃for 30 minutes, and then an excess of methanol was added dropwise to obtain a polyamide-imide powder. The powder was filtered under reduced pressure, dried, and redissolved in DMAc to prepare a polymer resin solution with a solids concentration of 14 wt%.
Casting the obtained polymer resin solution. Casting is performed using a casting substrate. There is no particular limitation on the type of casting substrate. As the casting substrate, a glass substrate, a stainless steel (SUS) substrate, a teflon substrate, or the like can be used. According to one embodiment of the present disclosure, an organic substrate may be used as the casting substrate.
Specifically, the resulting polymer resin solution was coated on a glass substrate, cast, and dried with hot air at 80 ℃ for 20 minutes, and dried at 120 ℃ for 20 minutes to manufacture a film. The fabricated film was then peeled from the glass substrate and pinned to the frame.
The frame with the immobilized membrane was placed in an oven and then dried with hot air at a constant temperature of 270 ℃ for 10 minutes. Thus, an optical film having a thickness of 50 μm was completed.
< example 2 to example 14>
Optical films of examples 2 to 14 were produced in the same manner as in example 1, except that the addition amount of the first diamine compound, the type and addition amount of the second diamine compound, the addition amount of the dianhydride compound, and the type and addition amount of the dicarbonyl compound were changed.
The details of the addition amount of the first diamine compound, the type and addition amount of the second diamine compound, the addition amount of the dianhydride compound, and the type and addition amount of the dicarbonyl compound of examples 1 to 14 are shown in table 1 below.
Comparative examples 1 to 3 ]
Optical films of comparative examples 1 to 3 were produced in the same manner as in example 1, except that the addition amount of the first diamine compound, whether the second diamine compound and the type and addition amount thereof, the addition amount of the dianhydride compound, and the type and addition amount of the dicarbonyl compound were changed.
The amounts of the first diamine compound, whether the second diamine compound was added and the type and amount thereof, the amount of the dianhydride compound added, and the type and amount of the dicarbonyl compound added of comparative examples 1 to 3 are shown in the following Table 1 in detail.
Comparative example 4 ]
While nitrogen was passing through the reactor, 313.34g of N, N-dimethylacetamide (DMAc) was charged into a 500mL reactor equipped with a stirrer, a nitrogen syringe, a dropping funnel, a temperature controller, and a cooler. Then, the temperature of the reactor was adjusted to 25 ℃, 28.8207g (0.090 mol) of TFDB as the first diamine compound was dissolved therein, 2.483g (0.010 mol) of bis (4-aminophenyl) sulfone (4 DDS) as the second diamine compound was further dissolved therein, and the resulting solution was maintained at 25 ℃. 5.8833g (0.030 mol) of cyclobutane-1, 2,3, 4-tetracarboxylic dianhydride (CBDA) and 2.2212g (0.005 mol) of 6FDA were added to the resulting diamine compound solution, and thoroughly dissolved therein by stirring for 2 hours. The reactor temperature was lowered to 10 ℃, 13.1989g (0.065 mol) of terephthaloyl chloride (TPC) was added thereto, completely dissolved, and reacted for 1 hour, and then the temperature was raised to 25 ℃. To the resultant reaction solution, 0.35g of pyridine and 0.45g of acetic anhydride were added, and stirred at 80℃for 30 minutes, and an excess of methanol was added dropwise to obtain a polyamide-imide powder. The powder was filtered under reduced pressure, dried, and redissolved in DMAc to prepare a polymer resin solution with a solids concentration of 14 wt%.
Casting the obtained polymer resin solution. Casting is performed using a casting substrate. There is no particular limitation on the type of casting substrate. As the casting substrate, a glass substrate, a stainless steel (SUS) substrate, a teflon substrate, or the like can be used. According to one embodiment of the present disclosure, an organic substrate may be used as the casting substrate.
Specifically, the resulting polymer resin solution was coated on a glass substrate, cast, and dried with hot air at 80 ℃ for 20 minutes, and dried at 120 ℃ for 20 minutes to manufacture a film. The fabricated film was then peeled from the glass substrate and pinned to the frame.
The frame with the immobilized membrane was placed in an oven and then dried with hot air at a constant temperature of 270 ℃ for 10 minutes. Thus, an optical film having a thickness of 50 μm was completed.
Comparative example 5 and comparative example 6 ]
Optical films of comparative examples 5 and 6 were produced in the same manner as in example 1, except that the addition amount of the first diamine compound, the addition amount of the second diamine compound, the addition amount of the dianhydride compound, and the addition amount of the dicarbonyl compound were changed.
The details of the addition amounts of the first diamine compound, the second diamine compound, the dianhydride compound, and the dicarbonyl compound of comparative examples 5 and 6 are shown in Table 1 below.
TABLE 1
TFDB:2,2' -bis (trifluoromethyl) benzidine
3DDS: bis (3-aminophenyl) sulfones
4DDS: bis (4-aminophenyl) sulfones
3,3' -6F:2, 2-bis (3-aminophenyl) hexafluoropropane
4,4' -6F:2, 2-bis (4-aminophenyl) hexafluoropropane
pPDA: para-phenylenediamine
8FODA: oxygen-4, 4' -bis (2, 3,5, 6-tetrafluoroaniline)
TPC: terephthaloyl chloride
BPDC:4,4' -Biphenyl dicarboxylic acid dichloride
CBDA: cyclobutane-1, 2,3, 4-tetracarboxylic dianhydride
< measurement example >
The following measurements were made on the polymer resins and films produced in examples 1 to 14 and comparative examples 1 to 6.
1) Weight average molecular weight of polymer resin: the weight average molecular weight of the polymer resin was measured using GPC (Alliance e2695/2414 RID, waters) under the following conditions.
A detector: 2414 RID, waters
Mobile phase: liBr in DMAc 10mM
Sample concentration: 0.25 (w/w) percent in DMAc
Column and detector temperature: 50 DEG C
Flow rate: 1.0ml/min
2) Modulus: modulus was measured using a universal tester (e.g., instron corp.) under the following conditions according to ASTM D882 standard.
-25℃/50RH％
A load sensor: 30KN, clamp: 250N
Sample size: 10X 50mm, stretching speed: 25mm/min
3) Poisson ratio: the poisson's ratio of the optical film was measured using the non-contact (video extensometer) method according to ASTM E-132 standard. Specifically, poisson's ratio was measured using a universal tester (e.g., instron 3367 of Instron corp. Under the following conditions).
Test speed: 10mm/min
-(25±2)℃/(45±5)％RH
4) Elastic Strain index (E'): the elastic strain index (E') of the optical film was calculated using a non-contact (video extensometer) method according to equation 2 below:
[ equation 2]
Elastic strain index (E')=e/(1-v) 2 )
5) Yellowness index (y.i.): the yellowness index was measured using a spectrophotometer (CM-3700D,KONICA MINOLTA) according to ASTM E313 standard.
6) Restoring force parameters after folding: the post-folding recovery force parameter of the optical film was calculated using the following equation 1:
[ equation 1]
Wherein R represents a radius of curvature of the optical film on a folding center line when folded, in mm, d represents a thickness of the optical film, in μm, and E' represents an elastic strain index, wherein only numerical values (excluding units) are applied to the radius of curvature and the thickness.
7) Transmittance (%): the average light transmittance at a wavelength of 360nm to 740nm was measured using a spectrophotometer (CM-3700D,KONICA MINOLTA).
8) Haze: haze was determined by cutting the manufactured optical film into samples having a size of 50mm×50mm, and measuring 5 times using a haze meter (model name: manufactured by HM-150,Murakami Color Research Laboratory) according to ASTM D1003, taking the average of 5 values as haze of the optical film.
9) Fold trace: samples of dimensions 100mm by 50mm randomly derived from the optical film were subjected to bending tests along a single bending axis. The bending test was performed by repeatedly bending a 100mm×50mm sample 200,000 times at a speed of 60rpm to a radius of curvature of 2.0mm (diameter of 4.0 mm) using a bending tester (YUASA, DLDM111 LHA) at 25 ℃/50 RH%. Then, fold marks occurring along the bending axis were analyzed.
At this time, an analysis method for sharpening the contrast (shadow) of the fold trace may be required. For example, imaging can be performed by inspecting foreign matter on the film. Various inspection methods such as reflection, scattering, and transmission methods are used to detect defects or indentations that are not noticeable using a CCD camera or the naked eye, if possible, in order to detect foreign substances having the same color as the film material. It is preferred to use an inspection (i.e. measurement) device instead of a measurement device.
Specifically, for example, the inspection apparatus includes three components, i.e., an inspection apparatus, a control unit (controller box: converting laser data received by the inspection apparatus into image data), and a dedicated PC (imaging PC: a PC on which a dedicated application program is installed, the dedicated application program being connected to the control unit (controller box) and being capable of image processing). That is, the analysis/evaluation may be performed by setting measurement/evaluation conditions, converting laser data into image data, and performing analysis using known software for analyzing brightness, saturation, reflectance, and the like of an image/photograph, but is not limited thereto.
The measurement results are shown in tables 2 and 3 below.
TABLE 2
TABLE 3
As can be seen from the measurement results of tables 2 and 3, examples 1 to 14 of the present disclosure have high weight average molecular weight and exhibit excellent yellowness index, light transmittance, and haze. In addition, the post-folding recovery force parameters of examples 1 to 14 of the present disclosure were all 1.5GPa or less, the elastic strain index (E') was 5.5GPa or more, and no folding trace (X) was left even after the bending test.
However, in comparative example 1, a film could not be produced due to gelation of the dicarbonyl-based compound. In comparative example 2, the resin had a low weight average molecular weight, and was poor in visibility due to high yellowness index and haze. In comparative example 2, the recovery force parameter after folding was 1.5GPa or less, but the elastic strain index (E') was less than 5.5GPa, so that a slight folding trace (. DELTA.) remained after the bending test. In comparative example 3, the recovery force parameter after folding was 1.5GPa or less, but the elastic strain index (E') was less than 5.5GPa, so that a slight folding trace remained after the bending test. In comparative example 4, the yellowness index and haze were high, the light transmittance was low, the post-folding recovery parameter was higher than 1.5GPa, and a serious folding trace (O) was left after the bending test. In comparative example 5, the yellowness index and haze were high, and the light transmittance was low, so the visibility was low. In comparative example 5, the post-folding recovery force parameter was 1.5GPa or less, but the elastic strain index (E') was less than 5.5GPa, and a slight folding trace (. DELTA.) was left after the bending test. In comparative example 6, the resin had a low weight average molecular weight, a high yellowness index and haze, and a low light transmittance, and thus was poor in visibility. In comparative example 6, the post-folding recovery force parameter was 1.5GPa or less, but the elastic strain index (E') was less than 5.5GPa, and a slight folding trace (. DELTA.) was left after the bending test.
[ description of reference numerals ]
100: optical film
200: display device
501: a display panel.

Claims (14)

1. An optical film comprising a polymer resin and having a yellowness index of 3.0 or less and a post-folding recovery parameter of 1.5GPa or less calculated using equation 1 below:
[ equation 1]
Wherein R is 0.5mm, which is the radius of curvature of the optical film on the fold centerline when folded;
d is the thickness of the optical film, expressed in μm;
e' is an elastic strain index calculated using the following equation 2,
wherein only values excluding units are applied to the radius of curvature and the thickness in equation 1,
[ equation 2]
Elastic strain index (E')=e/(1-v) 2 )
Wherein E is the modulus of the optical film, expressed as GPa,
v is the poisson's ratio of the optical film.
2. The optical film according to claim 1, wherein the elastic strain index (E') calculated using equation 2 is 5.5 or more.
3. The optical film of claim 1, wherein the polymer resin comprises imide repeating units and amide repeating units.
4. An optical film according to claim 3, wherein the amide repeating units are present in an amount of 80% or more of the total number of the imide repeating units and the amide repeating units.
5. An optical film according to claim 3, wherein the imide repeating unit comprises a first repeating unit and a second repeating unit.
6. An optical film according to claim 3, wherein the amide repeat unit comprises a third repeat unit and a fourth repeat unit.
7. The optical film according to claim 5, wherein the first repeating unit is an imide repeating unit formed by polymerization of a first diamine compound and a first dianhydride compound,
the second repeating unit is an imide repeating unit formed by polymerization of a second diamine compound and a second dianhydride compound.
8. The optical film according to claim 6, wherein the third repeating unit is an amide repeating unit formed by polymerization of the first diamine compound and the first dicarbonyl compound,
the fourth repeating unit is an amide repeating unit formed by polymerization of the second diamine compound and the second dicarbonyl compound.
9. The optical film according to claim 7 or 8, wherein the first diamine compound is 2,2' -bis (trifluoromethyl) benzidine (TFDB).
10. The optical film according to claim 7 or 8, wherein the second diamine compound comprises at least one functional group selected from sulfonyl, carbonyl, methylene, propylene, and halogen.
11. The optical film according to claim 7 or 8, wherein the second diamine compound comprises at least one selected from the group consisting of bis (3-aminophenyl) sulfone (3 DDS), bis (4-aminophenyl) sulfone (4 DDS), 2-bis (3-aminophenyl) hexafluoropropane (3, 3' -6F), 2-bis (4-aminophenyl) hexafluoropropane (4, 4' -6F), 4' -Methylenedianiline (MDA), 3' -diaminobenzophenone, 4' -diaminobenzophenone, and benzidine tetrachloride (CIBZ).
12. The optical film according to claim 7 or 8, wherein the molar ratio of the polymerized first diamine compound and the polymerized second diamine compound is 95:5 to 50:50.
13. The optical film of claim 1, wherein the polymer resin has a weight average molecular weight (Mw) of 200,000 to 500,000.
14. A display device, comprising:
a display panel; and
the optical film according to any one of claims 1 to 13 provided on the display panel.
CN202180100358.XA 2021-07-14 2021-12-24 Optical film having excellent folding property and display device including the same Pending CN117616072A (en)

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KR10-2021-0092397 2021-07-14
KR10-2021-0186219 2021-12-23
KR1020210186219A KR20230011842A (en) 2021-07-14 2021-12-23 Optical film having improved restoring force after folding and display apparatus comprising the same
PCT/KR2021/019823 WO2023286954A1 (en) 2021-07-14 2021-12-24 Optical film having excellent folding performance and display device comprising same

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