WO2020159183A1 - Polyimide-based polymer film, and substrate for display device and optical device, each using same - Google Patents

Abstract

The present invention relates to a polyimide-based polymer film, and a substrate for a display device and an optical device, each using same, wherein the polyimide-based polymer film is synthesized by a reaction between specifically structured acid anhydride compound and diamine compound, and thus can secure excellent optical characteristics even in conditions of high-temperature thermal treatment and can stably maintain optical characteristics even at additional thermal treatment.

Description

Polyimide resin film and substrate for display device using same, and optical device

Cross-citation with relevant application(s)

This application is for Korean Patent Application No. 10-2019-0013486 filed on February 1, 2019, Korean Patent Application No. 10-2019-0121176 for September 30, 2019, Korean Patent Application No. 10-2019 for September 30, 2019 -0121177, Korean Patent Application No. 10-2019-0121178 on September 30, 2019, Korean Patent Application No. 10-2019-0161494 on December 6, 2019, and Korean Patent Application No. 10 on December 6, 2019 -2019-0161495 claims the benefit of priority, and all content disclosed in the literature of the relevant Korean patent application is incorporated as part of this specification.

The present invention relates to a polyimide-based resin film, a substrate for a display device using the same, and an optical device capable of securing excellent optical properties even under high temperature heat treatment conditions and stably maintaining optical properties even during additional heat treatment.

The display device market is rapidly changing with a focus on flat panel displays (FPDs), which are easy to have a large area and can be thin and light. The flat panel display includes a liquid crystal display (LCD), an organic light emitting display (OLED), or an electrophoretic display (EPD).

In particular, in recent years, in order to further expand the application and use of such a flat panel display, attention has been focused on a so-called flexible display device in which a flexible substrate is applied to the flat panel display. The application of the flexible display device is mainly being studied mainly on mobile devices such as smart phones, and its application fields are gradually expanding.

In general, in manufacturing flexible display devices and lighting devices, TFT devices are manufactured by depositing a multilayer inorganic film such as a buffer layer, an active layer, and a gate insulator on a cured polyimide.

However, when light is emitted to the polyimide layer (substrate layer), the emission efficiency may be reduced by a difference between the refractive index of the multi-layered upper layer made of the inorganic film and the refractive index of the polyimide layer as described above.

In addition, when the polyimide material included in the polyimide layer (substrate layer) is cured at a high temperature of 400° C. or higher, a decrease in optical properties may occur due to deterioration of the polyimide.

Accordingly, development of a new polyimide capable of satisfying high heat resistance and excellent optical properties is required.

The present invention relates to a polyimide-based resin film capable of securing excellent optical properties even under high temperature heat treatment conditions and stably maintaining optical properties even during additional heat treatment.

In addition, the present invention is to provide a substrate for a display device using the polyimide-based resin film, and an optical device.

In order to solve the above problems, in the present specification, the polyimide-based resin containing a polyimide repeating unit represented by the following Chemical Formula 1 is included, and the absolute value of the yellow index change amount (ΔYI) obtained by the following Equation 1 is 4 The following is a polyimide-based resin film.

[Formula 1]

In Chemical Formula 1, X ₁ is a tetravalent functional group represented by the following Chemical Formula 2, Y ₁ is an aromatic divalent functional group having 15 or more carbon atoms with at least one substituted electron withdrawing functional group,

[Formula 2]

In Chemical Formula 2, Ar is a polycyclic aromatic divalent functional group,

[Equation 1]

Yellow index change (△YI) = YI _f- YI ₀

In Equation 1, YI _f is the final yellow index of the film obtained after heat treatment of the polyimide resin film at a temperature of 400° C. to 450° C. for 130 minutes to 200 minutes, and YI ₀ is a polyimide system before the heat treatment. It is the yellow index of the resin film.

Also provided in the present specification is a substrate for a display device comprising the polyimide-based resin film.

Also provided in the present specification is an optical device comprising the polyimide-based resin film.

Hereinafter, a polyimide resin film according to a specific embodiment of the present invention, a substrate for a display device using the same, and an optical device will be described in more detail.

Unless expressly stated in this specification, the terminology is only for referring to a specific embodiment, and is not intended to limit the present invention.

Singular forms used herein include plural forms unless the phrases clearly indicate the opposite.

As used herein, the meaning of'include' embodies a specific characteristic, region, integer, step, action, element, and/or component, and other specific characteristic, region, integer, step, action, element, component, and/or group. It does not exclude the existence or addition of.

In addition, in this specification, terms including an ordinal number such as'first' and'second' are used for the purpose of distinguishing one component from other components, and are not limited by the ordinal number. For example, within the scope of the present invention, the first component may also be referred to as the second component, and similarly, the second component may be referred to as the first component.

In the present specification, the (co)polymer means a polymer or a copolymer, and the polymer means a homopolymer composed of a single repeating unit, and the copolymer means a composite polymer containing two or more repeating units.

In the present specification, examples of the substituent are described below, but are not limited thereto.

In the present specification, the term "substitution" means that other functional groups are bonded in place of the hydrogen atom in the compound, and the position to be substituted is not limited to a position where the hydrogen atom is substituted, that is, a position where the substituent is substitutable, and is substituted when two or more are substituted. , 2 or more substituents may be the same or different from each other.

The term "substituted or unsubstituted" in this specification is deuterium; Halogen group; Cyano group; Nitro group; Hydroxy group; Carbonyl group; Ester groups; Imide group; Amide group; Primary amino group; Carboxy group; Sulfonic acid group; Sulfonamide groups; Phosphine oxide group; Alkoxy groups; Aryloxy group; Alkyl thioxy group; Arylthioxy group; Alkyl sulfoxy group; Aryl sulfoxyl group; Silyl group; Boron group; Alkyl groups; Cycloalkyl group; Alkenyl group; Aryl group; Aralkyl group; An alkenyl group; Alkyl aryl groups; Alkoxysilylalkyl groups; Arylphosphine group; Or substituted or unsubstituted with one or more substituents selected from the group consisting of heterocyclic groups containing one or more of N, O and S atoms, or substituted or unsubstituted with two or more substituents among the exemplified substituents above . For example, "a substituent having two or more substituents" may be a biphenyl group. That is, the biphenyl group may be an aryl group or may be interpreted as a substituent to which two phenyl groups are connected.

In this specification,

, or

Means a bond connected to another substituent, and a direct bond means a case in which a separate atom does not exist in a portion represented by L.

In this specification, aromatic (aromatic) is a property that satisfies the Huckels Rule (Huckels Rule), it can be defined as a case that satisfies all three conditions according to the Huckel rule.

1) There must be 4n+2 electrons that are completely conjugated by empty p-orbitals, unsaturated bonds, and hole electron pairs.

2) 4n+2 electrons must form a planar isomer and form a ring structure.

3) All atoms in the ring must be able to participate in conjugation.

In the present specification, the alkyl group is a monovalent functional group derived from alkane, and may be a straight chain or a branched chain, and the carbon number of the straight chain alkyl group is not particularly limited, but is preferably 1 to 20. Further, the number of carbon atoms in the branched chain alkyl group is 3 to 20. Specific examples of the alkyl group are methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n -Pentyl, isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl , n-heptyl, 1-methylhexyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl- Propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, 2,6-dimethylheptan-4-yl, and the like, but is not limited to these. The alkyl group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

In the present specification, the halo alkyl group means a functional group in which the halogen group is substituted with the aforementioned alkyl group, and examples of the halogen group include fluorine, chlorine, bromine or iodine. The haloalkyl group may be substituted or unsubstituted, and when substituted, examples of the substituent are as described above.

In the present specification, a multivalent functional group is a residue in which a plurality of hydrogen atoms bound to an arbitrary compound are removed, for example, a divalent functional group, a trivalent functional group, and a tetravalent functional group. For example, a tetravalent functional group derived from cyclobutane refers to a residue in which any 4 hydrogen atoms attached to cyclobutane are removed.

In this specification, the electron withdrawing group (Electro-withdrawing group) may include one or more selected from the group consisting of haloalkyl groups, halogen groups, cyano groups, nitro groups, sulfonic acid groups, carbonyl groups and sulfonyl groups, preferably It may be a haloalkyl group such as trifluoromethyl group (-CF ₃ ).

In the present specification, a direct bond or a single bond means that there is no atom or atomic group at the corresponding position, and is connected by a bond line. Specifically, it means that a separate atom is not present in a portion represented by L ₁ and L ₂ in the chemical formula.

In this specification, the weight average molecular weight means the weight average molecular weight of polystyrene conversion measured by GPC method. In the process of measuring the weight average molecular weight in terms of polystyrene measured by the GPC method, detectors and analytical columns, such as a commonly known analytical device and a differential index detector, can be used, and the temperature is usually applied. Conditions, solvents and flow rates can be applied. As a specific example of the above measurement conditions, using a Waters PL-GPC220 instrument using a Polymer Laboratories PLgel MIX-B 300mm length column, the evaluation temperature is 160°C, and 1,2,4-trichlorobenzene is used as a solvent. The flow rate was 1 mL/min, the sample was prepared at a concentration of 10 mg/10 mL, and then supplied in an amount of 200 μL, and the value of Mw can be obtained by using an assay curve formed using a polystyrene standard. The molecular weight of the polystyrene standard was 2,000 / 10,000 / 30,000 / 70,000 / 200,000 / 700,000 / 2,000,000 / 4,000,000 / 10,000,000.

Hereinafter, the present invention will be described in more detail.

1. Polyimide film

According to one embodiment of the invention, a polyimide containing a polyimide-based resin including a polyimide repeating unit represented by Chemical Formula 1, and having an absolute value of a change in yellow index (ΔYI) obtained by Equation 1 of 4 or less. Based resin film may be provided.

The present inventors, like the polyimide-based resin film of the above embodiment, the tetravalent functional group derived from the tetracarboxylic acid dianhydride having a specific structure as in Chemical Formula 2 in the polyimide repeating unit structure and the number of carbon atoms substituted with at least one electron withdrawing functional group As the aromatic divalent functional group of 15 or more was contained, the polyimide resin film cured at a high temperature of 400° C. or higher also had excellent optical properties through experiments, and the invention was completed.

In particular, the polyimide-based resin comprises a reaction product obtained through an imidization reaction of a tetracarboxylic dianhydride containing a structure represented by Formula 2 and an aromatic diamine having 15 or more carbon atoms substituted with at least one electron withdrawing functional group, By securing high heat resistance by physical and chemical action according to the novel structure of the acid anhydride monomer and aromatic diamine monomer, not only in the cured film through heat treatment at a high temperature of 400°C or higher, but also at an additional high temperature of 400°C or more for the cured film It appears that excellent optical properties are achieved even during heat treatment.

Specifically, a trifluoromethyl group (-CF3) capable of imparting an electron withdrawing effect to a diamine monomer compound used in the synthesis of polyimide resin is introduced as a substituent, and CTC (charge of Pi-electrons present in the imide chain) By suppressing the formation of transfer complex), transparency can be secured to realize excellent optical properties.

In addition, the polyimide-based resin synthesized from an aromatic diamine monomer having 15 or more carbon atoms with at least one electron withdrawing group functionally improves ordering and orientation characteristics between molecules to ensure sufficient heat resistance even in a polyimide film obtained by high temperature curing, thereby making it plastic. When used as a substrate, when heat-treating the metal layer formed on the plastic substrate, the plastic substrate is prevented from being damaged by heat, and excellent optical properties can be achieved even when heat treatment is performed at an additional high temperature of 400° C. or higher.

Specifically, the polyimide film according to the present invention can increase the refractive index, and is used as a substrate layer in a flexible display device, thereby reducing the difference in refractive index with each layer constituting the device. By reducing the amount of extinguished light, it is possible to effectively increase the emission efficiency of the light (bottom emission).

The polyimide-based resin means that polyimide and polyamic acid and polyamic acid ester, which are precursor polymers thereof, are all included. That is, the polyimide-based polymer may include at least one selected from the group consisting of a polyamic acid repeating unit, a polyamic acid ester repeating unit, and a polyimide repeating unit. That is, the polyimide-based polymer may include a polyamic acid repeating unit, one polyamic acid ester repeating unit, one polyimide repeating unit, or a copolymer of two or more repeating units thereof.

One or more repeating units selected from the group consisting of the polyamic acid repeating unit, polyamic acid ester repeating unit, and polyimide repeating unit may form a main chain of the polyimide-based polymer.

In particular, the polyimide-based resin may include a polyimide repeating unit represented by Chemical Formula 1.

In Chemical Formula 1, X ₁ is a tetravalent functional group represented by Chemical Formula 2, and X ₁ is a functional group derived from a tetracarboxylic acid dianhydride compound used in the synthesis of polyimide resins.

In the formula (2), Ar is a polycyclic aromatic divalent functional group. The polycyclic aromatic divalent functional group may be a polycyclic aromatic hydrocarbon compound or a divalent functional group derived from a derivative compound thereof, and may include a fluorenylene group. The derivative compound includes all compounds in which one or more substituents are introduced or carbon atoms are replaced by heteroatoms.

More specifically, in Ar of Formula 2, the polycyclic aromatic divalent functional group may include a conjugated cyclic divalent functional group containing at least two or more aromatic ring compounds. That is, the polycyclic aromatic divalent functional group may contain at least two or more aromatic ring compounds in the functional group structure, as well as the functional group may have a fused ring structure.

The aromatic ring compound may include an arene compound containing at least one benzene ring, or a hetero arene compound in which carbon atoms in the arene compound are replaced by heteroatoms.

The aromatic ring compound may contain at least two or more in the polycyclic aromatic divalent functional group, and each of the two or more aromatic ring compounds may form a direct fused ring or a fused ring through a different ring structure. For example, when two benzene rings are respectively bonded to a cycloalkyl ring structure, it can be defined that two benzene rings each form a cycloalkyl ring.

The conjugated cyclic divalent functional group containing at least two or more aromatic cyclic compounds is a divalent functional group derived from a conjugated cyclic compound containing at least two or more aromatic cyclic compounds or a derivative compound thereof, wherein the derivative compound has one or more substituents introduced Or a compound in which the carbon atom has been replaced with a heteroatom.

Examples of the polycyclic aromatic divalent functional group are not particularly limited, and examples thereof include a fluorenylene group.

The tetravalent functional group represented by Chemical Formula 2 may be a functional group represented by Chemical Formula 2-1.

[Formula 2-1]

In Formula 1, Y ₁ is an aromatic divalent functional group having 15 or more carbon atoms substituted with at least one electron withdrawing group, and Y ₁ is an action derived from a diamine compound used in the synthesis of polyamic acid, polyamic acid ester, or polyimide. It can be a flag.

The aromatic divalent functional group having 15 or more carbon atoms in Y ₁ may include three or more aromatic cyclic compounds. As such, as three or more aromatic cyclic compounds are contained, the ordering and orientation characteristics of the polyimide-based resin are improved, and sufficient heat resistance can be secured even in a polyimide film obtained by high temperature curing.

The aromatic divalent functional group having 15 or more carbon atoms may include at least one selected from the group consisting of a triphenylene group, a quaterphenylene group, and a pentaphenylene group.

The electron withdrawing functional group may include at least one selected from the group consisting of haloalkyl groups, halogen groups, cyano groups, nitro groups, sulfonic acid groups, carbonyl groups and sulfonyl groups.

As electron withdrawing substituents such as trifluoromethyl group (-CF ₃ ) having high electronegativity are substituted, the effect of suppressing the formation of charge transfer complex (CTC) of Pi-electrons present in the polyimide resin chain is increased. Accordingly, improved transparency can be secured. That is, packing within the polyimide structure or between chains can be reduced, and electrical interactions between chromogens can be weakened due to steric hindrance and electrical effects, resulting in high transparency in the visible region.

More specifically, the aromatic divalent functional group having 15 or more carbon atoms substituted with at least one electron withdrawing functional group of Y ₁ may include a functional group represented by the following Chemical Formula 3.

[Formula 3]

In Chemical Formula 3, T ₁ to T ₃ are the same or different from each other, each independently an electron withdrawing group, m1 to m3 are the same or different from each other, and at least one of m1 to m3 is an integer of 1 to 4, the rest Is an integer from 0 to 4, and n is an integer from 1 to 10.

An aromatic divalent functional group having 15 or more carbon atoms substituted with at least one electron withdrawing functional group of Y ₁ may include a functional group represented by the following Chemical Formula 3-1.

[Formula 3-1]

.

The polyimide-based resin may include a combination of tetracarboxylic acid dianhydride represented by the following Chemical Formula 4 and aromatic diamine having 15 or more carbon atoms substituted with at least one electron withdrawing functional group.

[Formula 4]

In the above formula (4), Ar' is a polycyclic aromatic divalent functional group. The polycyclic aromatic divalent functional group is a divalent functional group derived from a polycyclic aromatic hydrocarbon compound, and may include a fluorenylene group as a divalent functional group derived from a fluorenylene group or a derivative compound thereof. . The derivative compound includes all compounds in which one or more substituents are introduced or carbon atoms are replaced by heteroatoms.

A specific example of the tetracarboxylic acid dianhydride represented by Chemical Formula 4 is 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride (9,9-Bis(3,4-dicarboxyphenyl)fluorene Dianhydride, BPAF). Can be lifted.

The aromatic diamine having 15 or more carbon atoms in which the electron withdrawing functional group is substituted by at least 1 is a compound in which an amino group (-NH ₂ ) is bonded to the sock end of the aromatic di2 having 15 or more carbon atoms in which the electron withdrawing functional group is substituted by at least 1, The description of the aromatic divalent functional group having 15 or more carbon atoms in which the electron withdrawing functional group is substituted by at least one is as described above.

Specific examples of the aromatic diamine having 15 or more carbon atoms in which the electron withdrawing functional group is substituted with at least one or more include diamine represented by the following formula (a).

[Formula a]

More specifically, the polyimide-based resin has a terminal anhydride group (-OC-O-CO-) of tetracarboxylic acid dianhydride represented by Chemical Formula 4 and an aromatic diamine having at least 15 carbon atoms substituted with at least one electron withdrawing group. The reaction between the amino group (-NH ₂ ) may form a bond between the nitrogen atom of the amino group and the carbon atom of the anhydride group.

The polyimide-based resin may further include a polyimide repeating unit represented by Formula 5 below.

[Formula 5]

In Chemical Formula 5, X ₂ is one of a tetravalent functional group represented by the following Chemical Formula 6, and Y ₂ is an aromatic divalent functional group having 15 or more carbon atoms with at least one substituted electron withdrawing functional group,

[Formula 6]

In Formula 6, R ₁ to R ₆ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, and L is a single bond, -O-, -CO-, -COO-, -S-, -SO-,- SO ₂ -, -CR ₇ R ₈ -, -(CH ₂ ) _t -, -O(CH ₂ ) _t O-, -COO(CH ₂ ) _t OCO-, -CONH-, phenylene or combinations thereof Any one selected from the group consisting of, wherein R ₇ and R ₈ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a halo alkyl group having 1 to 10 carbon atoms, and t is an integer of 1 to 10.

Specific examples of the functional group represented by Chemical Formula 6 include functional groups represented by Chemical Formula 6-1, functional groups represented by Chemical Formula 6-2, or functional groups represented by Chemical Formula 6-3.

[Formula 6-1]

[Formula 6-2]

[Formula 6-3]

That is, the polyimide-based polymer includes: a first repeating unit containing a repeating unit represented by Formula 1, wherein a repeating unit derived from tetracarboxylic acid dianhydride is a functional group represented by Formula 2; And a second repeating unit containing a repeating unit represented by Formula 5, wherein the repeating unit derived from tetracarboxylic dianhydride is a functional group represented by Formula 6 above. The first repeating unit and the second repeating unit are randomly arranged in the polyimide-based polymer to form a random copolymer, or a block between the first repeating unit and a block between the second repeating units to form a block copolymer. Can.

The polyimide-based polymer including the repeating unit represented by Chemical Formula 1 and the repeating unit represented by Chemical Formula 5 may be prepared by reacting two or more different tetracarboxylic acid dianhydride compounds with diamine compounds. Tetracarboxylic acid dianhydride may be added simultaneously to synthesize a random copolymer, or sequentially added to synthesize a block copolymer.

The polyimide repeating unit represented by Chemical Formula 5 may contain 1 mol% or more and 99 mol% or less of all the repeating units contained in the polyimide resin.

The polyimide repeating unit represented by Formula 1 and the polyimide repeating unit represented by Formula 5 are 70 mol% or more, or 80 mol% or more, or 90 mol% or more, compared to the total repeating units contained in the polyimide-based resin, or 70 mol% or more, 100 mol% or less, 80 mol% or more, 100 mol% or less, 70 mol% or more, 90 mol% or less, 70 mol% or more, 99 mol% or less, 80 mol% or more, 99 mol% or less, 90 mol% or more, 99 or more 99 It may contain less than mol%.

That is, the polyimide-based resin is composed of only the polyimide repeating unit represented by Formula 1 and the polyimide repeating unit represented by Formula 5, or most of the polyimide repeating unit represented by Formula 1 and Formula 5 It may be made of polyimide repeat units.

More specifically, in the polyimide-based resin, other diamines other than diamines capable of inducing aromatic divalent functional groups having 15 or more carbon atoms substituted with at least one electron withdrawing functional group are not mixed, or may be mixed in an extremely small amount of less than 1 mol%. have.

More specifically, the polyimide repeating unit represented by Chemical Formula 5, the polyimide repeating unit represented by Chemical Formula 5-1, the polyimide repeating unit represented by Chemical Formula 5-2, and the polyyi represented by Chemical Formula 5-3: It may include one or more repeat units selected from the group consisting of mid repeat units.

[Formula 5-1]

In Chemical Formula 5-1, X ₃ is a tetravalent functional group represented by Chemical Formula 6-1, Y ₃ is an aromatic divalent functional group having 15 or more carbon atoms with at least one substituted electron withdrawing functional group,

[Formula 5-2]

In Chemical Formula 5-2, X ₄ is a tetravalent functional group represented by Chemical Formula 6-2, and Y ₄ is an aromatic divalent functional group having 15 or more carbon atoms with at least one substituted electron withdrawing functional group,

[Formula 5-3]

In Chemical Formula 5-3, X ₅ is a tetravalent functional group represented by Chemical Formula 6-3, and Y ₅ is an aromatic divalent functional group having 15 or more carbon atoms with at least one substituted electron withdrawing functional group.

The weight average molecular weight (measured by GPC) of the polyimide-based resin is not particularly limited, but may be, for example, 1000 g/mol or more and 200000 g/mol or less, or 10000 g/mol or more and 200000 g/mol or less.

The polyimide-based resin according to the present invention can exhibit excellent colorless and transparent characteristics while maintaining characteristics such as heat resistance, mechanical strength, etc. due to a rigid structure, an element substrate, a display substrate for a display, and an optical film , IC (integrated circuit) package, electrodeposition film (adhesive film), multi-layer flexible printed circuit (FRC), tape, touch panel, protective film for optical disk, etc. can be used in various fields, especially suitable for display cover board have.

Meanwhile, the polyimide-based resin film of the embodiment may include a cured product in which the polyimide-based resin is cured at a temperature of 400° C. or higher. The cured product means a material obtained through a curing process of a resin composition containing the polyimide-based resin, and the curing process is performed at a temperature of 400° C. or higher, or 400° C. or higher and 500° C. or lower, for 50 minutes to 100 minutes. Can proceed.

More specifically, an example of a method for synthesizing the polyimide-based resin film is not particularly limited, and for example, forming a coating film by applying a resin composition containing the polyimide-based resin to a substrate (step 1); Drying the coating film (step 2); A method of manufacturing the film may be used, including the step of curing the dried coating film by heat treatment (step 3).

Step 1 is a step of forming a coating film by applying a resin composition containing the above-described polyimide resin to a substrate. The method of applying the resin composition containing the polyimide-based resin to the substrate is not particularly limited, and for example, methods such as screen printing, offset printing, flexo printing, inkjet, and the like can be used.

In addition, the resin composition containing the polyimide resin may be dissolved or dispersed in an organic solvent. When it has such a form, for example, when the polyimide-type resin is synthesize|combined in an organic solvent, the solution may be the reaction solution itself obtained, and the reaction solution may be diluted with another solvent. In addition, when a polyimide resin is obtained as a powder, it may be dissolved in an organic solvent to form a solution.

Specific examples of the organic solvent include toluene, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N-ethyl Pyrrolidone, N-vinylpyrrolidone, dimethylsulfoxide, tetramethylurea, pyridine, dimethylsulfone, hexamethylsulfoxide, gamma-butyrolactone, 3-methoxy-N,N-dimethylpropanamide, 3- Ethoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, 1,3-dimethyl-imidazolidinone, ethyl amyl ketone, methylnonyl ketone, methyl ethyl ketone, methyl isoa Milk ketone, methyl isopropyl ketone, cyclohexanone, ethylene carbonate, propylene carbonate, diglyme, 4-hydroxy-4-methyl-2-pentanone, ethylene glycol monomethyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol Monoethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether, ethylene glycol monopropyl ether acetate, ethylene glycol monoisopropyl ether, ethylene glycol monoisopropyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol monobutyl ether And acetate. These may be used alone or in combination.

The resin composition containing the polyimide-based resin may contain solid content in an amount to have an appropriate viscosity in consideration of processability such as coatability during the film forming process. For example, the content of the composition may be adjusted such that the total resin content is 5% to 25% by weight, or 5% to 20% by weight, or 5% to 15% by weight. .

In addition, the resin composition containing the polyimide-based resin may further include other components in addition to the organic solvent. As a non-limiting example, when the resin composition containing the polyimide-based resin is applied, it improves the uniformity or surface smoothness of the film thickness, or improves the adhesion to the substrate, or changes the dielectric constant or conductivity. Or, additives that can increase the density may be further included. Examples of such additives include surfactants, silane-based compounds, dielectric or cross-linkable compounds, and the like.

The step 2 is a step of drying the coating film formed by applying the resin composition containing the polyimide resin to the substrate.

The drying step of the coating film may be performed by heating means such as a hot plate, a hot air circulation path, an infrared furnace, and may be performed at a temperature of 50°C or more and 150°C or less, or 50°C or more and 100°C or less.

Step 3 is a step of curing the dried coating film by heat treatment. At this time, the heat treatment may be performed by heating means such as a hot plate, a hot air circulation path, an infrared furnace, and may be performed at a temperature of 400°C or higher, or 400°C or higher and 500°C or lower.

Although the thickness of the polyimide-based resin film is not particularly limited, for example, it can be freely adjusted within a range of 0.01 μm or more and 1000 μm or less. When the thickness of the polyimide-based resin film increases or decreases by a specific value, physical properties measured in the polyimide-based resin film may also change by a certain value.

On the other hand, in the polyimide-based resin film, the absolute value of the amount of change in the yellow index obtained by Equation 1 below is 4 or less, or 3.5 or less, or 0.01 or more and 4 or less, or 0.01 or more and 3.5 or less, or 0.05 or more and 4 or less, or 0.05 Or more and 3.5 or less, or 0.1 or more and 4 or less, or 0.1 or more and 3.5 or less.

[Equation 1]

Yellow index change (△YI) = YI _f- YI ₀

In Equation 1, YI _f is the final yellow index of the film obtained after heat treatment of the polyimide resin film at a temperature of 400° C. to 450° C. for 130 minutes to 200 minutes, and YI ₀ is a polyimide system before the heat treatment. It is the yellow index of the resin film.

Since the value of the change in yellow index obtained in Equation 1 may have a negative or positive value, the change in the actual yellow index according to the additional heat treatment can be compared through the absolute value of the amount of change in yellow index obtained in Equation 1. When the yellow index change amount obtained in Equation 1 is a negative number (eg, -1), the absolute value of the yellow index change amount obtained in Equation 1 may be a value with a negative sign removed (eg 1). . When the yellow index change amount obtained in Equation 1 is a positive number (for example, 1), the absolute value of the yellow index change amount obtained in Equation 1 is a yellow index change amount value (eg, 1) obtained in Equation 1 Is the same as

In YI _f of Equation 1, an example of a method of heat-treating the polyimide-based resin film at a temperature of 400°C to 450°C for 130 minutes to 200 minutes is not particularly limited, and the heat treatment may be performed in a single step, or in multiple steps. Can proceed to In the case of the multi-step, an additional heat treatment process of 2 to 10 steps may be performed, and in this case, each step may be performed continuously or discontinuously.

However, when heat treatment is sequentially performed, each heat treatment step is performed at a temperature of 400°C to 450°C, and the total sum of the times of each heat treatment step satisfies 130 minutes to 200 minutes.

That is, even though heat treatment conditions at a high temperature of 400° C. or higher are added to the polyimide-based resin film of the above embodiment, the absolute value of the amount of change in the yellow index, which is the optical property of the film, is very small to 4 or less, so the polyimide of the above embodiment Based resin film can achieve high heat resistance.

When the polyimide-based resin film sample used for the yellow index measurement is made of pure polyimide-based resin film only, the yellow index is a result of analyzing a polyimide-based resin film sample with a color meter (Color-Eye 7000A of GRETAGMACBETH). It can be measured automatically. For example, a pure polyimide-based resin film may be secured through a process of peeling the base film from a laminate including a base film and a polyimide-based resin film coated on the base film.

The yellow index may be measured for a sample of a polyimide resin film of one embodiment having a thickness of 5 μm or more and 30 μm or less, or 5 μm or more and 15 μm or less, or 8 μm or more and 12 μm or less.

In Equation 1, the yellow index of the polyimide resin film before the heat treatment is 15 or less, or 14.5 or less, or 1 or more 15 or less, or 1 or more 14.5 or less, or 5 or more 15 or less, or 5 or more 14.5 or less, or 8.8 or more and 14.1 or less. The polyimide resin film, which is a yellow index measurement target of the polyimide resin film before the heat treatment, refers to a material obtained through a curing process of a resin composition containing a polyimide resin as described above, and the curing process is, for example, For example, at a temperature of 400° C. or higher, or 400° C. or higher and 500° C. or lower, the temperature may be 50 minutes or more and 100 minutes or less.

In addition, in Equation 1, the final yellow index of the polyimide-based resin film is 20 or less, or 18 or less, or 5 or more 20 or less, or 5 or more 18 or less, or 8 or more 20 or less, or 8 or more and 18 or less, Or 8.7 or more and 17.6 or less. The final yellow index measurement target polyimide-based resin film means a film obtained after further heat-treating the polyimide-based resin film at a temperature of 400°C to 450°C for 130 minutes to 200 minutes as described above, and the heat treatment Is as described above in Equation (1).

As described above, by introducing a trifluoromethyl group (-CF ₃ ) capable of imparting an electron withdrawing effect to the diamine monomer compound used in the synthesis of the polyimide-based resin as a substituent, the Pi-electron present in the imide chain By suppressing the formation of their charge transfer complex (CTC), transparency can be secured to realize excellent optical properties.

2. Substrate for display device

Meanwhile, according to another embodiment of the present invention, a substrate for a display device including the polyimide-based resin film of the other embodiment may be provided. The contents of the polyimide-based resin film may include all of the contents described above in one embodiment.

The display device including the substrate is a liquid crystal display device (LCD), an organic light emitting diode (OLED), a flexible display (Flexible Display), or a rollable display device (rollable display or foldable display) ) And the like, but is not limited thereto.

The display device may have various structures depending on the application field and the specific shape, for example, a structure including a cover plastic window, a touch panel, a polarizing plate, a barrier film, a light emitting device (such as an OLED device), and a transparent substrate. have.

The polyimide-based resin film of the other embodiments described above may be used for various purposes such as a substrate, an external protective film, or a cover window in these various display devices, and more specifically, may be applied as a substrate.

For example, the substrate for a display device may have a structure in which a device protection layer, a transparent electrode layer, a silicon oxide layer, a polyimide resin film, a silicon oxide layer, and a hard coating layer are sequentially stacked.

The transparent polyimide substrate may include a silicon oxide layer formed between the transparent polyimide-based resin film and the cured layer in terms of further improving solvent resistance, moisture permeability, and optical properties, and the silicon oxide layer is poly It may be produced by curing silazane.

Specifically, the silicon oxide layer is formed by curing the coated polysilazane after coating and drying a solution containing polysilazane before the step of forming a coating layer on at least one surface of the transparent polyimide resin film. May be

The substrate for a display device according to the present invention can provide a transparent polyimide cover substrate having solvent resistance, optical properties, moisture permeability, and scratch resistance, while having excellent bending properties and impact resistance by including the above-described device protection layer. have.

3. Optical device

Meanwhile, according to another embodiment of the present invention, an optical device including the polyimide-based resin film of the other embodiment may be provided. The contents of the polyimide-based resin film may include all of the contents described above in one embodiment.

The optical device may include all of various devices using properties realized by light, for example, a display device. Specific examples of the display device include a liquid crystal display device (LCD), an organic light emitting diode (OLED), a flexible display, or a rollable display or foldable display And the like, but is not limited thereto.

The optical device may have various structures according to application fields and specific shapes, and may be, for example, a structure including a cover plastic window, a touch panel, a polarizing plate, a barrier film, a light emitting device (such as an OLED device), and a transparent substrate. have.

The polyimide-based resin film of the other embodiments described above may be used in various applications such as a substrate, an external protective film, or a cover window in these various optical devices, and more specifically, may be applied to a substrate.

According to the present invention, a polyimide-based resin film and a substrate for a display device using the same and a polyimide resin film capable of securing excellent optical properties under high temperature heat treatment conditions and stably maintaining optical properties even during additional heat treatment are provided. Can be.

The invention is described in more detail in the following examples. However, the following examples are only illustrative of the present invention, and the contents of the present invention are not limited by the following examples.

<Example: Preparation of polyimide film>

Example 1

(1) Preparation of polyimide precursor composition

After filling the organic solvent DEAc in a stirrer through which a nitrogen stream flowed, 0.735 mol of diamine represented by the following formula (a) was dissolved at the same temperature while maintaining the temperature of the reactor at 25°C. 9,9-bis(3,4-dicarboxyphenyl)fluorene dianhydride represented by the following formula (b) as an acid dianhydride in the solution to which the diamine represented by the following formula (a) is added (9,9-Bis(3,4- dicarboxyphenyl)fluorene Dianhydride, BPAF) 0.3675 mol and 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride, BPDA) 0.3675 mol were added at the same temperature The mixture was stirred for 24 hours to obtain a polyimide precursor composition.

[Formula a]

[Formula b]

(2) Preparation of polyimide film

The polyimide precursor composition was spin coated on a glass substrate. The glass substrate coated with the polyimide precursor composition was placed in an oven, heated at a rate of 5°C/min, and maintained at 80°C for 20 minutes and at 450°C for 70 minutes to undergo a curing process to perform a polyimide film (thickness: 10 μm) ) Was prepared.

Example 2

4,4'-(hexafluoroisopropylidene)di instead of 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride, BPDA) as acid dianhydride A polyimide film was prepared in the same manner as in Example 1, except that phthalic anhydride (4,4'-(Hexafluoroisopropylidene) diphthalic anhydride, 6-FDA) was used.

Example 3

As an acid dianhydride, pyromellitic dianhydride (PMDA) was used instead of 3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride (BPDA)). A polyimide film was manufactured in the same manner as in Example 1, except that.

<Comparative Example: Preparation of polyimide film>

Comparative Example 1

(1) Preparation of polyimide precursor composition

After filling the organic solvent DEAc in a stirrer through which a nitrogen stream flows, 2,2'-bis(trifluoromethyl)benzidine) (2,2'-bis(trifluoromethyl)benzidine) while maintaining the temperature of the reactor at 25°C , TFMB) 0.735 mol was added at the same temperature to dissolve. 2,2'-bis(trifluoromethyl)benzidine) (2,2'-bis(trifluoromethyl)benzidine), 3,3',4 represented by the following formula (b) as an acid dianhydride in a solution added with TFMB) 0.735 mol of 4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride, BPDA) was added at the same temperature and stirred for 24 hours to obtain a polyimide precursor composition.

(2) Preparation of polyimide film

The polyimide precursor composition was spin coated on a glass substrate. The glass substrate coated with the polyimide precursor composition was placed in an oven, heated at a rate of 5°C/min, and maintained at 80°C for 20 minutes and at 450°C for 70 minutes to undergo a curing process to perform a polyimide film (thickness: 10 μm) ) Was prepared.

Comparative Example 2

3,3',4,4'-biphenyltetracarboxylic dianhydride (3,3',4,4'-Biphenyltetracarboxylic dianhydride, BPDA) 0.3675 mol, 4,4'-(hexafluoroisopropylidene ) Diphthalic anhydride (4,4'-(Hexafluoroisopropylidene) diphthalic anhydride, 6-FDA) except that 0.3675 mol was added, a polyimide film was prepared in the same manner as in Comparative Example 1.

Comparative Example 3

Pyromellitic dianhydride (PMDA) 0.3675 mol, 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (4,4'-(Hexafluoroisopropylidene) diphthalic anhydride, 6-FDA) A polyimide film was prepared in the same manner as in Comparative Example 1, except that 0.3675 mol was added.

<Experimental Example: Measurement of physical properties of polyimide films obtained in Examples and Comparative Examples>

The physical properties from the polyimide films obtained in Examples and Comparative Examples were measured by the following methods, and the results are shown in Tables 1 and 2.

1. Yellow index (YI ₀ ) (450 ℃ / 70 minutes curing)

The polyimide film having a thickness of 10 μm obtained in Examples and Comparative Examples was peeled from a glass substrate, and after preparing a sample having a size of 2 cm X 10 cm in width, a color meter (Color-Eye 7000A by GRETAGMACBETH) was used for the sample. Then, the yellow index (YI ₀ ) was obtained and is shown in Table 1 below.

2. Heat resistant yellow index (△YI)

(1) Additional conditions for one time high temperature heat curing (450 ℃/70 minutes → 410 ℃/60 minutes curing)

After the polyimide film having a thickness of 10 μm obtained in Examples and Comparative Examples was further cured at 410° C. for 60 minutes, the film was peeled from the glass substrate, and a sample having a size of 2 cm X 10 cm in width was prepared, followed by color to the sample. The final yellow index (YI _f ) was measured using a meter (GRETAGMACBETH's Color-Eye 7000A), and the amount of change in yellow index (ΔYI) according to Equation 1 below was calculated to obtain a heat-resistant yellow index and is shown in Table 1 below. .

(2) Additional conditions for two times of high temperature heat curing (450 ℃/70 minutes → 410 ℃/60 minutes → 445 ℃/60 minutes curing)

The polyimide film having a thickness of 10 μm obtained in Examples and Comparative Examples was further cured at 410° C. for 60 minutes, and then the film further cured at 445° C. for 60 minutes was peeled from the glass substrate, and the size was 2 cm by 10 cm. After preparing the sample, the final yellow index (YI _f ) was measured using a color meter (Color-Eye 7000A manufactured by GRETAGMACBETH), and the amount of change in yellow index (ΔYI) by Equation 1 below was calculated. The heat-resistant yellow index was obtained and is shown in Table 1 below.

(3) Additional conditions for two times of high temperature heat curing (450 ℃/70 minutes → 445 ℃/30 minutes → 445 ℃/30 minutes curing)

The polyimide film having a thickness of 10 μm obtained in Examples and Comparative Examples was further cured at 445° C. for 30 minutes, and then the film cured for an additional 30 minutes at 445° C. was peeled from the glass substrate, and the size was 2 cm X 10 cm After preparing the sample, the final yellow index (YI _f ) was measured using a color meter (Color-Eye 7000A manufactured by GRETAGMACBETH), and the amount of change in yellow index (ΔYI) by Equation 1 below was calculated. The heat-resistant yellow index was obtained and is shown in Table 1 below.

[Equation 1]

Yellow index change amount (△YI) = (final yellow index obtained in Experimental Example 2 (YI _f ))-(yellow index obtained in Experimental Example 1 (YI ₀ ))

Experimental Example Measurement Results of Examples and Comparative Examples

division	Yellow index (YI 0 )	Final yellow index (YI f )			Heat-resistant yellow index (△YI)
High temperature curing conditions	450 ℃/70 minutes	450 ℃ / 70 minutes → 410 ℃ / 60 minutes	450 ℃ / 70 minutes → 410 ℃ / 60 minutes → 445 ℃ / 60 minutes	450 ℃/70 minutes → 445 ℃/30 minutes →445 ℃/30 minutes	450 ℃ / 70 minutes → 410 ℃ / 60 minutes	450 ℃ / 70 minutes → 410 ℃ / 60 minutes → 445 ℃ / 60 minutes	450 ℃ / 70 minutes → 445 ℃ / 30 minutes → 445 ℃ / 30 minutes
Example 1	8.8	9.5	11.3	8.7	0.7	2.5	-0.1
Example 2	12.1	12.0	13.3	15.3	-0.1	1.2	3.2
Example 3	14.1	14.8	16.2	17.6	0.7	2.1	3.5
Comparative Example 1	16.8	24.6	39.8	21.3	4.5	7.8	23.0
Comparative Example 2	15.2	22.5	40.7	21.1	5.9	7.3	25.5
Comparative Example 3	15.9	23.9	42.5	22.5	6.6	8.0	26.6

As shown in Table 1, the polyimide resin films of Examples 1 to 3 obtained through a curing process at 450°C for 70 minutes exhibited a yellow index (YI ₀ ) of 8.8 or more and 14.1 or less. The polyimide resin films of Comparative Examples 1 to 3 obtained through the curing process at 70 minutes exhibited a yellow index (YI ₀ ) of 15.2 or more and 16.8 or less, which is much higher than in Examples. Through this, the polyimide system of Examples It was confirmed that the resin film can have excellent optical properties even when curing at a high temperature of 400°C or higher.

In addition, the polyimide-based resin films of Examples 1 to 3 are heat resistant yellow index (△YI) of -0.2 or more and 3.5 or less, or yellow index change amount of 0.1 or more and 3.5 or less (△) YI).

On the other hand, when the polyimide-based resin films of Comparative Examples 1 to 3 were subjected to additional heat treatment at a high temperature of 400° C. or higher, heat resistance yellow index (ΔYI) of 4.5 or more and 26.6 or less, or 4.5 or more and 26.6 or less, which is much higher than in Examples. The absolute value of the yellow index change amount (ΔYI) was shown.

Through this, it was confirmed that the optical properties of the polyimide-based resin film of the embodiment can be stably maintained even at a high temperature heat treatment of 400° C. or higher for the film.

Claims (18)

1. A polyimide-based resin comprising a polyimide repeating unit represented by the following Chemical Formula 1,

   A polyimide-based resin film having an absolute value of the yellow index change amount (ΔYI) obtained by Equation 1 below 4 or less:

   [Formula 1]

   

   In Chemical Formula 1,

   X ₁ is a tetravalent functional group represented by the following formula (2),

   Y ₁ is an aromatic divalent functional group having 15 or more carbon atoms substituted with at least one electron withdrawing functional group,

   [Formula 2]

   

   In Chemical Formula 2, Ar is a polycyclic aromatic divalent functional group,

   [Equation 1]

   Yellow index change (△YI) = YI _f- YI ₀

   In Equation 1,

   YI _f is the final yellow index of the film obtained after heat treatment of the polyimide resin film at a temperature of 400°C to 450°C for 130 minutes to 200 minutes,

   YI ₀ is the yellow index of the polyimide-based resin film before the heat treatment.
2. According to claim 1,

   A polyimide-based resin film having an absolute value of the amount of change in yellow index (ΔYI) obtained by Equation 1 below 3.5.
3. According to claim 1,

   The polyimide-based resin film having a yellow index of 15 or less of the polyimide-based resin film before the heat treatment.
4. According to claim 1,

   The polyimide-based resin film having a final yellow index of 20 or less of the polyimide-based resin film.
5. According to claim 1,

   In Ar of Formula 2, a polycyclic aromatic divalent functional group

   A polyimide-based resin film comprising a fused cyclic divalent functional group containing at least two aromatic cyclic compounds.
6. According to claim 1,

   In Ar of Formula 2, the polycyclic aromatic divalent functional group comprises a fluorenylene group, a polyimide-based resin film.
7. According to claim 1,

   The tetravalent functional group represented by Chemical Formula 2 includes a functional group represented by Chemical Formula 2-1, and a polyimide-based resin film:

   [Formula 2-1]

   

   .
8. According to claim 1,

   A polyimide-based resin film, wherein the aromatic divalent functional group having 15 or more carbon atoms in Y ₁ includes three or more aromatic cyclic compounds.
9. The method of claim 8,

   The aromatic divalent functional group having 15 or more carbon atoms includes at least one member selected from the group consisting of a triphenylene group, a quaterphenylene group, and a pentaphenylene group, and a polyimide resin film.
10. According to claim 1,

    The electron withdrawing functional group includes at least one selected from the group consisting of haloalkyl groups, halogen groups, cyano groups, nitro groups, sulfonic acid groups, carbonyl groups and sulfonyl groups, polyimide-based resin film.
11. According to claim 1,

    The aromatic divalent functional group having 15 or more carbon atoms in which the electron withdrawing functional group of Y ₁ is substituted by at least 1, includes a functional group represented by the following Chemical Formula 3:

    [Formula 3]

    

    In Chemical Formula 3,

    T ₁ to T ₃ are the same or different from each other, each independently an electron withdrawing group,

    m1 to m3 are the same as or different from each other, at least one of m1 to m3 is an integer from 1 to 4, and the other is an integer from 0 to 4,

    n is an integer from 1 to 10.
12. According to claim 1,

    A polyimide-based resin film comprising a functional group represented by the following Chemical Formula 3-1, wherein the aromatic divalent functional group having 15 or more carbon atoms in which the electron withdrawing functional group of Y ₁ is substituted by at least one or more:

    [Formula 3-1]

    

    .
13. According to claim 1,

    The polyimide-based resin comprises a combination of a tetracarboxylic acid dianhydride represented by the following Chemical Formula 4 and an aromatic diamine having 15 or more carbon atoms substituted with at least one electron withdrawing functional group, a polyimide-based resin film:

    [Formula 4]

    

    In the above formula (4), Ar' is a polycyclic aromatic divalent functional group.
14. According to claim 1,

    The polyimide-based resin further includes a polyimide repeating unit represented by Chemical Formula 5, a polyimide-based resin film:

    [Formula 5]

    

    In Chemical Formula 5,

    X ₂ is one of the tetravalent functional groups represented by the following formula (6),

    Y ₂ is an aromatic divalent functional group having 15 or more carbon atoms substituted with at least one electron withdrawing functional group,

    [Formula 6]

    

    In Formula 6, R ₁ to R ₆ are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, and L is a single bond, -O-, -CO-, -COO-, -S-, -SO-,- SO ₂ -, -CR ₇ R ₈ -, -(CH ₂ ) _t -, -O(CH ₂ ) _t O-, -COO(CH ₂ ) _t OCO-, -CONH-, phenylene or combinations thereof Any one selected from the group consisting of, wherein R ₇ and R ₈ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms, or a halo alkyl group having 1 to 10 carbon atoms, and t is an integer of 1 to 10.
15. The method of claim 14,

    The polyimide repeating unit represented by Chemical Formula 5 and the polyimide repeating unit represented by Chemical Formula 1 contain 70 mol% or more of the total repeating units contained in the polyimide resin, and the polyimide resin film.
16. According to claim 1,

    The polyimide-based resin film, the polyimide-based resin film containing a cured product cured at a temperature of 400 °C or higher.
17. A substrate for a display device comprising the polyimide-based resin film of claim 1.
18. An optical device comprising the polyimide-based resin film of claim 1.