Composition, retardation film for organic electroluminescent display device, and method for producing retardation film for organic electroluminescent display device
阅读说明：本技术 组合物、有机电致发光显示元件用相位差膜、有机电致发光显示元件用相位差膜的制造方法 (Composition, retardation film for organic electroluminescent display device, and method for producing retardation film for organic electroluminescent display device ) 是由 山崎健太 金子若彦 加茂诚 于 2019-01-17 设计创作，主要内容包括：本发明提供一种能够在有机EL显示元件上的规定的位置上形成相位差膜且应用了相位差膜的有机EL显示装置的显示性能优异的组合物、有机EL显示元件用相位差膜及有机EL显示元件用相位差膜的制造方法。本发明的组合物为包含具有亲水性基团、交联性基团及介晶基团的聚合物以及聚合性化合物,且用于形成配置于有机电致发光显示元件上的相位差膜的组合物。(The invention provides a composition which can form a phase difference film on a specified position on an organic EL display element and is used for an organic EL display device with the phase difference film, the composition has excellent display performance, the phase difference film for the organic EL display element and a manufacturing method of the phase difference film for the organic EL display element. The composition of the present invention is a composition for forming a retardation film disposed on an organic electroluminescent display device, the composition including a polymer having a hydrophilic group, a crosslinkable group, and a mesogenic group, and a polymerizable compound.)
1. A composition, comprising:
a polymer having a hydrophilic group, a crosslinkable group and a mesogenic group; and
a polymerizable compound which is a mixture of a polymerizable compound,
the composition is used for forming a phase difference film configured on an organic electroluminescent display element.
2. The composition of claim 1, wherein,
the polymer comprises a repeating unit having the crosslinkable group and the mesogenic group.
3. The composition of claim 1 or 2,
the hydrophilic group and the crosslinkable group can be reacted by heating.
4. The composition according to any one of claims 1 to 3,
the crosslinkable group is a group selected from the group consisting of an oxetanyl group and an epoxy group.
5. The composition according to any one of claims 1 to 4,
the hydrophilic group is a group selected from the group consisting of a carboxyl group and a phenolic hydroxyl group.
6. The composition of any one of claims 1 to 5, wherein the composition further comprises a polymerization initiator.
7. The composition according to any one of claims 1 to 6,
the polymerizable compound is a polymerizable liquid crystal compound.
8. A retardation film for an organic electroluminescent display element, which is formed using the composition according to any one of claims 1 to 7.
9. The retardation film for an organic electroluminescent display element according to claim 8, which is a λ/4 plate or a λ/2 plate.
10. The retardation film for an organic electroluminescent display element according to claim 8 or 9, which exhibits reverse wavelength dispersibility.
11. An organic electroluminescent display device comprising:
an organic electroluminescent display element; and
the retardation film for an organic electroluminescent display element according to any one of claims 8 to 10, which is disposed on an organic electroluminescent display element.
12. A method for manufacturing a retardation film for an organic electroluminescent display device, comprising:
a step of forming a coating film on a substrate provided with an organic electroluminescent display element, using the composition according to any one of claims 1 to 7;
a step of aligning the mesogenic groups in the coating film;
exposing a part of the coating film; and
and developing the exposed coating film to form a retardation film for an organic electroluminescent display device on the organic electroluminescent display device.
Technical Field
The present invention relates to a composition, a retardation film for an organic electroluminescent display device, and a method for producing a retardation film for an organic electroluminescent display device.
Background
The retardation film having refractive index anisotropy is applicable to various applications such as an antireflection film for a display device and an optical compensation film for a liquid crystal display device. In particular, in recent years, in order to suppress adverse effects caused by external light reflection, a circularly polarizing plate including a retardation film is used for an organic Electroluminescence (EL) display device (patent document 1).
Prior art documents
Patent document
Patent document 1: japanese laid-open patent publication No. 9-127885
Disclosure of Invention
Technical problem to be solved by the invention
Conventionally, in the manufacture of an organic EL display device including a retardation film, as shown in fig. 1, a plurality of organic
Next, the mother substrate is cut to produce a laminate including the
On the other hand, in recent years, from the viewpoint of improving the thickness reduction and flexibility of an organic EL display device, a method of directly forming a retardation film on an organic EL display element has been desired. In this case, a method of forming a retardation film by applying the composition for forming a retardation film to an organic EL display device is considered.
However, when a conventional composition for forming a retardation film is used, the retardation film is formed so as to cover the connection terminals of the organic EL display device, and the retardation film cannot be formed only at a desired position.
In view of the above circumstances, an object of the present invention is to provide a composition which can form a retardation film at a predetermined position on an organic EL display device and is excellent in display performance of an organic EL display device to which the retardation film is applied.
Another object of the present invention is to provide a retardation film for an organic EL display device and a method for manufacturing the retardation film for an organic EL display device.
Means for solving the technical problem
The present inventors have intensively studied the problems of the prior art and found that the above problems can be solved by using a composition having a predetermined composition.
That is, the following configuration was found to solve the above problems.
(1) A composition, comprising:
a polymer having a hydrophilic group, a crosslinkable group, and a mesogenic group; and
a polymerizable compound which is a mixture of a polymerizable compound,
for forming a retardation film disposed on the organic electroluminescent display element.
(2) The composition according to (1), wherein,
the polymer comprises a repeating unit having a crosslinkable group and a mesogenic group.
(3) The composition according to (1) or (2), wherein,
the hydrophilic group and the crosslinkable group can be reacted by heating.
(4) The composition according to any one of (1) to (3), wherein,
the crosslinkable group is a group selected from the group consisting of an oxetanyl group and an epoxy group.
(5) The composition according to any one of (1) to (4), wherein,
the hydrophilic group is a group selected from the group consisting of a carboxyl group and a phenolic hydroxyl group.
(6) The composition according to any one of (1) to (5), further comprising a polymerization initiator.
(7) The composition according to any one of (1) to (6), wherein,
the polymerizable compound is a polymerizable liquid crystal compound.
(8) A retardation film for an organic electroluminescent display element, which is formed using the composition described in any one of (1) to (7).
(9) The retardation film for an organic electroluminescent display element according to (8), which is a λ/4 plate or a λ/2 plate.
(10) The retardation film for organic electroluminescent display elements according to (8) or (9), which exhibits reverse wavelength dispersibility.
(11) An organic electroluminescent display device comprising:
an organic electroluminescent display element; and
(8) the retardation film for an organic electroluminescent display device according to any one of (1) to (10), which is disposed on the organic electroluminescent display device.
(12) A method for manufacturing a retardation film for an organic electroluminescent display device, comprising:
a step of forming a coating film on a substrate provided with an organic electroluminescent display element, using the composition described in any one of (1) to (7); a step of aligning mesogenic groups in the coating film; exposing a part of the coating film; and developing the exposed coating film to form a retardation film for an organic electroluminescent display device on the organic electroluminescent display device.
Effects of the invention
According to the present invention, a composition which can form a retardation film at a predetermined position on an organic EL display element and is excellent in display performance of an organic EL display device to which the retardation film is applied can be provided.
Further, the present invention can provide a retardation film for an organic EL display device and a method for manufacturing the retardation film for an organic EL display device.
Drawings
Fig. 1 is a diagram showing a process for manufacturing an organic EL display device according to the related art.
Fig. 2 is a diagram showing a process for manufacturing an organic EL display device according to the related art.
Fig. 3 is a diagram showing a process for manufacturing an organic EL display device according to the related art.
Fig. 4 is a diagram for explaining the steps of step 1.
Fig. 5 is a diagram for explaining the steps of step 3.
Fig. 6 is a diagram for explaining the steps of step 4.
Detailed Description
The present invention will be described in detail below. In the present specification, the numerical range expressed by the term "to" means a range in which the numerical values described before and after the term "to" are included as the lower limit value and the upper limit value. First, terms used in the present specification will be described.
In the present invention, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively. When not specifically mentioned, the wavelength λ is 550 nm.
In the present invention, Re (. lamda.) and Rth (. lamda.) are values measured at a wavelength of λ in Axoscan OPMF-1 (manufactured by Opto Science, Inc.). The following was calculated by using the AxoSacan input average refractive index ((nx + ny + nz)/3) and film thickness (d (μm)):
slow axis direction (°)
Re(λ)＝R0(λ)
Rth(λ)＝((nx+ny)/2-nz)×d。
R0 (. lamda.) is a numerical value calculated by Axoscan OPMF-1, but refers to Re (. lamda.).
In the present specification, the refractive indices nx, ny, and nz are measured using an abbe refractive index (NAR-4T, ATAGO co., LTD) and a sodium lamp (λ 589nm) as a light source. When the wavelength dependence is measured, the measurement can be performed by a combination with an interference filter using a multi-wavelength abbe refractometer DR-M2(ATAGO co., LTD).
Also, a polymer handbook (JOHN wide & SONS, INC), the values of the product catalog of various optical films can be used. The values of the average refractive index of the main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), polystyrene (1.59).
In the present specification, the Nz factor is a value given by Nz ═ (nx-Nz)/(nx-ny).
In the present specification, "visible light" refers to light having a wavelength of 380 to 780 nm.
In the present specification, the range of an error that is allowable in the technical field to which the present invention pertains is included in terms of an angle (for example, an angle such as "90 °") and a relationship thereof (for example, "perpendicular", "parallel", and "cross at 45 °). For example, the error from the precise angle is preferably 5 ° or less, more preferably 3 ° or less, in a range of the precise angle ± 10 ° or the like.
In the present specification, the "absorption axis" of the polarizer means the direction in which the absorbance is highest. The "transmission axis" refers to a direction forming an angle of 90 ° with the "absorption axis".
One of the characteristics of the composition for forming a retardation film to be disposed on the organic electroluminescent display device of the present invention (composition for forming a retardation film for organic electroluminescence) (hereinafter, also simply referred to as "composition of the present invention") is that a polymer having a hydrophilic group, a crosslinkable group, and a mesogenic group is used.
The polymer having a hydrophilic group imparts developability to a coating film described in detail later. Further, since the polymer has a crosslinkable group, phase separation between the polymers and/or between the polymer and the polymerizable compound can be suppressed, and as a result, the organic EL display device has excellent display performance. Further, the polymer has a mesogenic group, and thus a retardation can be exhibited. In addition, when the composition of the present invention contains a polymerizable liquid crystal compound, the polymer has a mesogenic group, so that the compatibility between the polymer and the polymerizable liquid crystal compound is excellent, and the coating film can be effectively removed by a developer
The composition of the present invention comprises a polymer having a hydrophilic group, a crosslinkable group and a mesogenic group, and a polymerizable compound.
The components contained in the composition of the present invention will be described in detail below.
< Polymer having hydrophilic group, crosslinkable group and mesogenic group >
The polymer has a hydrophilic group.
Examples of the hydrophilic group include a carboxyl group, a hydroxyl group, a sulfo group, and an amino group. Among them, from the viewpoint of more excellent reactivity with a crosslinkable group described later, a carboxyl group or a phenolic hydroxyl group is preferable, and a carboxyl group is more preferable.
The phenolic hydroxyl group means a hydroxyl group directly bonded to an aromatic hydrocarbon ring group.
The polymer preferably comprises repeating units having hydrophilic groups. The number of the hydrophilic groups in each repeating unit is not particularly limited, and may be 1 or more (2 or more).
The number of hydrophilic groups may be only 1, or may be 2 or more.
As the repeating unit having a hydrophilic group, a repeating unit represented by formula (1) is preferable.
[ chemical formula 1]
R1Represents a hydrogen atom or an alkyl group.
L1Represents a single bond or a 2-valent linking group. The 2-valent linking group is not particularly limited, but examples thereof include those selected from the group consisting of-O-, -CO-, -NRAAnd any 1 or 2 or more of the group of 2-valent hydrocarbon groups. RARepresents a hydrogen atom or an alkyl group。
Examples of the above-mentioned hydrocarbon group having a valence of 2 include an alkylene group, an alkenylene group (e.g., -CH-), an alkynylene group (e.g., -C.ident.C-) and an arylene group (e.g., -phenylene). The alkylene group may be linear, branched or cyclic. The number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, and still more preferably 1 to 4.
X represents a hydrophilic group. The hydrophilic group is as defined above.
Further, as described above, the polymer preferably contains a repeating unit having a carboxyl group or a phenolic hydroxyl group.
Examples of the repeating unit having a carboxyl group include repeating units derived from an unsaturated carboxylic acid. Examples of the unsaturated carboxylic acid include an unsaturated monocarboxylic acid and an unsaturated polyvalent carboxylic acid.
Examples of the unsaturated monocarboxylic acid include acrylic acid, methacrylic acid, crotonic acid, α -chloroacrylic acid, cinnamic acid, 2- (meth) acryloyloxyethyl-succinic acid, 2- (meth) acryloyloxyethylhexahydrophthalic acid, and 2- (meth) acryloyloxyethyl-phthalic acid.
Examples of the unsaturated polyvalent carboxylic acid include maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid.
Also, the unsaturated polyvalent carboxylic acid may be an acid anhydride thereof. Specific examples thereof include maleic anhydride, itaconic anhydride and citraconic anhydride.
The unsaturated polyvalent carboxylic acid may be a mono (2-methacryloyloxyalkyl) ester of a polyvalent carboxylic acid, and examples thereof include succinic acid mono (2-acryloyloxyethyl group), succinic acid mono (2-methacryloyloxyethyl group), phthalic acid mono (2-acryloyloxyethyl group) and phthalic acid mono (2-methacryloyloxyethyl group).
The unsaturated polyvalent carboxylic acid may be a mono (meth) acrylate of a dicarboxylic polymer at both ends thereof, and examples thereof include ω -carboxy polycaprolactone monoacrylate and ω -carboxy polycaprolactone monomethacrylate.
Further, as the unsaturated carboxylic acid, 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, monoalkyl maleate, monoalkyl fumarate and 4-carboxystyrene may be mentioned.
Specific examples of the repeating unit having a carboxyl group include the following.
[ chemical formula 2]
Examples of the repeating unit having a phenolic hydroxyl group include a repeating unit represented by the formula (1-1).
[ chemical formula 3]
R11Represents a hydrogen atom or an alkyl group.
L11Represents a single bond or a 2-valent linking group. Definition of the 2-valent linking group1The definition of the 2-valent linking group is the same.
R12Represents a halogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms.
a represents an integer of 1 to 5, b represents an integer of 0 to 4, and a + b is 5 or less.
In addition, there are more than 2R12In the case of (2), these R' s12May be different from each other or may be identical to each other.
The content of the repeating unit having a hydrophilic group in the polymer is not particularly limited, but is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, based on the mass (100% by mass) of all the repeating units in the polymer, from the viewpoint of obtaining at least one of the viewpoint of easier formation of a retardation film at a predetermined position and the viewpoint of more excellent display performance of an organic EL display device to which the retardation film is applied (hereinafter, also simply referred to as "the viewpoint of more excellent effects of the present invention").
The number of the repeating units having a hydrophilic group may be 1 or 2 or more.
The polymer has a crosslinkable group. The crosslinkable group is a group different from the hydrophilic group.
Examples of the crosslinkable group include an oxetanyl group, an epoxy group, an acryloyl group, a methacryloyl group, a thiol group, a halogenated benzyl group, a carboxylic anhydride group, a cyanate group, an isocyanate group, an aldehyde group, an aziridine group, and an alkoxysilyl group.
In addition, as the combination of the hydrophilic group and the crosslinkable group, it is preferable that the hydrophilic group and the crosslinkable group can be reacted by heating from the viewpoint that the chemical resistance of the retardation film is more excellent. Examples of the combination of such a hydrophilic group and a crosslinkable group include a combination of a carboxyl group and an oxetanyl group, a combination of a carboxyl group and an epoxy group, a combination of a phenolic hydroxyl group and an oxetanyl group, and a combination of a phenolic hydroxyl group and an epoxy group.
The polymer preferably contains a repeating unit having a crosslinkable group.
As the repeating unit having a crosslinkable group, a repeating unit represented by formula (2) is preferable.
[ chemical formula 4]
R2Represents a hydrogen atom or an alkyl group.
L2Represents a single bond or a 2-valent linking group. Definition of the 2-valent linking group1The definition of the 2-valent linking group is the same.
As described in detail later, the repeating unit having a crosslinkable group may have both mesogenic groups, and may be, for example, L2Comprising mesogenic groups.
Y represents a crosslinkable group. The crosslinkable group is as defined above.
The content of the repeating unit having a crosslinkable group in the polymer is not particularly limited, but from the viewpoint of further improving the effect of the present invention, it is preferably 5 to 85% by mass, more preferably 20 to 80% by mass, based on the mass of all the repeating units in the polymer.
The number of repeating units having a crosslinkable group may be 1 or 2 or more.
The polymer has mesogenic groups.
The mesogenic group means a functional group having rigidity and orientation. Examples of the structure of the mesogenic group include a plurality of groups selected from the group consisting of aromatic ring groups (aromatic hydrocarbon ring groups and aromatic heterocyclic groups) and alicyclic ring groups, directly or via a 2-valent linking group (e.g., -CO-, -O-, -NR)A-(RARepresents a hydrogen atom or an alkyl group) or a group obtained by combining these).
More specifically, examples of the mesogenic group include groups represented by the formula (a).
Formulas (A) - (L)a-Lb)n-
LaRepresents an aromatic ring group having a valence of 2 or an alicyclic ring group having a valence of 2.
The aromatic ring group having a valence of 2 includes an aromatic ring group having a valence of 2 (for example, phenylene group) and an aromatic heterocyclic group having a valence of 2.
As the alicyclic group having a valence of 2, a cyclohexylene group may be mentioned.
LbRepresents a single bond, -CO-, -O-, -NR-AOr a combination thereof (e.g., -CO-O-). RARepresents a hydrogen atom or an alkyl group.
n represents an integer of 2 or more. Among them, 2 to 5 are preferable, and 2 to 3 are more preferable.
The polymer preferably comprises repeating units having mesogenic groups.
The content of the repeating unit having a mesogenic group in the polymer is not particularly limited, but from the viewpoint of further improving the effect of the present invention, it is preferably 5 to 85% by mass, more preferably 20 to 80% by mass, based on the mass of all the repeating units in the polymer.
Only 1 kind of repeating unit having a mesogenic group may be used, or 2 or more kinds may be used.
In the polymer, 2 or more selected from the group consisting of a hydrophilic group, a crosslinkable group and a mesogenic group may be contained in the same repeating unit. Among them, from the viewpoint of further improving the effect of the present invention, the polymer preferably contains a repeating unit having a crosslinkable group and a mesogenic group. Examples of the repeating unit having a crosslinkable group and a mesogenic group include a repeating unit represented by formula (3).
[ chemical formula 5]
La、LbAnd n is as defined in formula (A).
R3Represents a hydrogen atom or an alkyl group.
L3And L4Represents a single bond or a 2-valent linking group. Definition of the 2-valent linking group1The definition of the 2-valent linking group is the same.
In addition, as a group consisting of L3And L4As the 2-valent linking group, there may be mentioned, for example, -CO-O-, -CO-O-alkylene-O-, - (O-alkylene)mand-CO-O- (alkylene-O)m-. m represents an integer of 2 or more, and the upper limit is not particularly limited, but is preferably 5 or less.
Z represents a crosslinkable group. The crosslinkable group is as defined above.
The content of the repeating unit having a crosslinkable group and a mesogenic group in the polymer is not particularly limited, but is preferably 50 to 95% by mass, more preferably 60 to 90% by mass, based on the mass of all the repeating units in the polymer, from the viewpoint that the effect of the present invention is more excellent.
The repeating unit having a crosslinkable group and a mesogenic group may be used in only 1 kind, or may be used in 2 or more kinds.
The following may be mentioned as monomers constituting the repeating unit represented by the formula (3) by polymerization. In addition, 1 acryloyl group in the following monomers was polymerized to constitute a repeating unit represented by formula (3).
[ chemical formula 6]
The polymer may further contain a repeating unit other than the above-described repeating unit (a repeating unit having a hydrophilic group, a repeating unit having a crosslinkable group, a repeating unit having a mesogenic group, and a repeating unit having a crosslinkable group and a mesogenic group).
Examples of the monomer capable of constituting another repeating unit include styrenes, alkyl (meth) acrylates, cyclic alkyl (meth) acrylates, aryl (meth) acrylates, unsaturated dicarboxylic diesters, bicyclic unsaturated compounds, maleimide compounds, unsaturated aromatic compounds, conjugated diene compounds, and other unsaturated compounds.
The weight average molecular weight of the polymer is preferably 1000 to 200000, more preferably 2000 to 50000, in terms of polystyrene-reduced weight average molecular weight.
The ratio of the number average molecular weight to the weight average molecular weight (dispersion degree) is preferably 1.0 to 5.0, more preferably 1.0 to 3.5.
In the measurement based on the GPC (Gel Permeation Chromatography) method, for example, HLC-8120 (manufactured by Tosoh Corporation), TSKgel Mult ipore HXL-M (manufactured by Tosohcorporation, 7.8 mmID. times.30.0 cm) as a column, and T HF (tetrahydrofuran) as a dissolution liquid can be used.
The acid value of the polymer is not particularly limited, but is preferably 20 to 300mgKOH/mg, more preferably 50 to 250mgKOH/mg, from the viewpoint of further improving the effect of the present invention.
The method for synthesizing the polymer is not particularly limited, and known methods may be used. For example, there is a method of: a mixture containing a radical polymerizable monomer having a hydrophilic group, a radical polymerizable monomer having a crosslinkable group, and a radical polymerizable monomer having a mesogenic group is polymerized in an organic solvent using a radical polymerization initiator.
The content of the polymer in the composition of the present invention is not particularly limited, but is preferably 10 to 95% by mass, more preferably 20 to 90% by mass, and still more preferably 20 to 80% by mass, based on the total solid content in the composition, from the viewpoint of further improving the effect of the present invention.
The solid component is a component capable of forming a retardation film, and does not contain a solvent. In addition, even if the component capable of forming the retardation film is in a liquid state, it is handled as a solid component.
< polymerizable Compound >
The polymerizable compound is a compound having a polymerizable group.
The type of the polymerizable group is not particularly limited, and a polymerizable group capable of radical polymerization or cationic polymerization is preferable.
As the radical polymerizable group, a known radical polymerizable group can be used, and an acryloyl group or a methacryloyl group is preferable.
As the cationically polymerizable group, a known cationically polymerizable group can be used, and specific examples thereof include an alicyclic ether group, a cyclic acetal group, a cyclic lactone group, a cyclic thioether group, a spiroorthoester group, and a vinyloxy group.
The number of the polymerizable groups in the polymerizable compound is not particularly limited, but is preferably 6 or less.
Further, it is also preferable that the polymerizable compound has both a radical polymerizable group and a cation polymerizable group.
Examples of the polymerizable compound include a polyfunctional radical polymerizable compound. Specifically, there are polymerizable compounds described in paragraphs [0018] to [0020] in Japanese patent laid-open No. 2002-296423.
The polymerizable compound is preferably a polymerizable liquid crystal compound. The polymerizable liquid crystal compound is a compound having a polymerizable group and exhibiting liquid crystallinity.
The type of the polymerizable liquid crystal compound is not particularly limited, but can be classified into a rod-like type (rod-like liquid crystal compound) and a discotic type (discotic liquid crystal compound). And, respectively, have a low molecular type and a high molecular type. The polymer generally refers to a polymer having a polymerization degree of 100 or more (polymer physical/phase transition kinetics, Tujing, 2 nd page, Shibo bookshop, 1992). Further, 2 or more kinds of rod-like liquid crystal compounds, 2 or more kinds of discotic liquid crystal compounds, or a mixture of rod-like liquid crystal compounds and discotic liquid crystal compounds may be used.
The content of the polymerizable compound in the composition of the present invention is not particularly limited, but is preferably 5 to 85 mass%, more preferably 20 to 70 mass%, based on the total solid content in the composition, from the viewpoint of further improving the effect of the present invention.
< Others >
The composition of the present invention may further contain other components in addition to the above-mentioned polymer and polymerizable compound.
For example, the composition of the present invention may further comprise a polymerization initiator. The polymerization initiator to be used is selected depending on the form of the polymerization reaction, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator. Examples of the photopolymerization initiator include α -carbonyl compounds, acyloin ethers, α -hydrocarbon-substituted aromatic acyloin compounds, polynuclear quinone compounds, and combinations of triarylimidazole dimers and p-aminobenzones.
The content of the polymerization initiator in the composition is preferably 0.01 to 20% by mass, more preferably 0.5 to 5% by mass, based on the total solid content of the composition of the present invention.
Also, the composition of the present invention may further comprise a surfactant.
The surfactant includes conventionally known compounds, but a fluorine-based compound is preferable. Examples thereof include compounds described in paragraphs [0028] to [0056] of Japanese patent application laid-open No. 2001-330725 and compounds described in paragraphs [0069] to [0126] of Japanese patent application laid-open No. 2003-295212.
The composition of the present invention may further contain a curing agent having a reactive group capable of reacting with the crosslinkable group. The number of reactive groups in the curing agent is not particularly limited, but is preferably 2 or more, more preferably 2 to 6.
The kind of the reactive group is not particularly limited, and an optimum one is selected depending on the kind of the crosslinkable group. For example, when the crosslinkable group is an oxetanyl group, the reactive group may be a carboxyl group.
Also, the composition of the present invention may further comprise a solvent. As the solvent, an organic solvent is preferable. Examples of the organic solvent include amides (e.g., N-dimethylformamide), sulfoxides (e.g., dimethyl sulfoxide), heterocyclic compounds (e.g., pyridine), hydrocarbons (e.g., benzene and hexane), alkyl halides (e.g., chloroform and dichloromethane), esters (e.g., methyl acetate, ethyl acetate and butyl acetate), ketones (e.g., acetone and methyl ethyl ketone), and ethers (e.g., tetrahydrofuran and 1, 2-dimethoxyethane). In addition, 2 or more organic solvents may be used simultaneously.
The composition may contain various alignment control agents such as a vertical alignment agent and a horizontal alignment agent. These alignment control agents are compounds capable of controlling the alignment of the polymerizable liquid crystal compound to be horizontal or vertical on the surface side. Also, a chiral agent may be included in the composition, in which case a twisted nematic phase or a cholesteric phase can be developed.
In addition to the above components, the composition may further contain an adhesion improving agent, a coloring agent, a plasticizer, and the like.
< method for producing retardation film >
The composition of the present invention is used for forming a retardation film disposed on an organic EL display device. As described above, by using the composition of the present invention, a retardation film can be formed at a predetermined position.
The method for forming a retardation film for an organic EL display element of the present invention comprises the following steps 1 to 4.
Step 1: a step of bringing the composition of the present invention into contact with a substrate on which an organic EL display element is disposed to form a coating film thereon
And a step 2: process for aligning mesogenic groups in coating film
Step 3: a step of exposing a part of the coating film
And step 4: developing the exposed coating film to form a retardation film on the organic EL display device
The steps of each step will be described in detail below.
(step 1)
Step 1 is a step of forming a coating film on a substrate on which an organic EL display element is disposed, using the composition of the present invention. By performing this step, as shown in fig. 4, a laminate including a
The type of substrate supporting the organic EL display element is not particularly limited, and examples thereof include a glass substrate, a metal substrate, a ceramic substrate, a semiconductor substrate, and a resin substrate.
The structure of the organic EL display element is not particularly limited, but generally includes at least a pair of electrodes (cathode and anode) and an organic light-emitting layer disposed between the electrodes.
The organic EL display element generally includes an organic light emitting layer and a connection terminal for connection to an IC. Further, the organic EL display element may further include other components, for example, a sealing layer covering the organic light emitting layer.
As shown in fig. 1, a plurality of organic EL display elements may be arranged on the substrate.
The method of forming a coating film using the composition of the present invention is not particularly limited, and examples thereof include a method of applying the composition of the present invention to the substrate. Examples of the coating method include a curtain coating method, a spin coating method, a slit coating method, a print coating method, a spray coating method, a blade coating method, a gravure coating method, and a wire bar method.
If necessary, an alignment layer may be formed on a substrate on which an organic EL display element is disposed before a coating film is formed using the composition of the present invention. The alignment layer may be disposed at least on the upper side (the side opposite to the substrate) of the organic light-emitting layer in the organic EL display element, and preferably not on the connection terminal.
Generally, the alignment layer has a polymer as a main component. As the polymer for an alignment layer, there are many documents describing that a plurality of commercial products can be obtained. The polymer used is preferably polyvinyl alcohol (PVA), polyimide or derivatives thereof.
Further, as the alignment layer, a layer subjected to a known rubbing treatment is preferable. Further, as the alignment layer, a photo-alignment layer may be used.
In particular, when regions having different alignment directions are formed in the plane of the retardation film, a photo-alignment layer is preferably used from the viewpoint that patterning can be easily achieved by adjusting the polarization axis of polarized light irradiation in the photo-alignment treatment.
As the photo-alignment layer, a known material can be used, but it is preferable to use a photo-curable photo-alignment layer because it is not necessary to apply heat to the substrate and it is possible to form a high-quality alignment layer without surface defects due to friction debris and a film sheet generated at the time of peeling.
As such a material, for example, a composition for forming a photo-alignment layer containing a polymer having a photo-alignment group, a polymerizable monomer, and a photopolymerization initiator can be used. Specifically, the composition can be described in paragraph 0241 in Japanese patent application laid-open No. 2014-533376, paragraph 0087 in Japanese patent application laid-open No. 2015-527615, and paragraph 0134 in Japanese patent application laid-open No. 2016-535158.
The thickness of the orientation layer is preferably 0.01 to 10 μm.
The alignment layer may be removed at the same time in step 4 described later.
In the case of the above-mentioned photocurable alignment film, the alignment film can be removed in advance by preventing photocuring by shielding light or the like in a region where the coating film is removed in step 4 described later, such as a wiring connection portion, and then rinsing the substrate with a suitable solvent, a developing solution, or the like before step 2 described later. Thus, when the retardation film is removed in step 4, the region on the substrate can be exposed.
(step 2)
Step 2 is a step of aligning the mesogenic groups in the coating film. When the coating film contains a polymerizable liquid crystal compound, both the mesogenic group and the polymerizable liquid crystal compound are aligned in step 2.
Specific treatment methods (alignment treatment) in step 2 include a method of heating the coating film and a method of drying the coating film at room temperature. When the liquid crystal phase formed in the alignment treatment is a thermotropic liquid crystal compound, the thermotropic liquid crystal compound can be generally transferred according to a change in temperature. In the case of a lyotropic liquid crystal compound, the amount can be changed depending on the composition ratio such as the amount of the solvent.
The conditions for heating the coating film are not particularly limited, but the heating temperature is preferably 50 to 150 ℃ and the heating time is preferably 10 seconds to 5 minutes.
(step 3)
Step 3 is a step of exposing a part of the coating film. In this step, as shown in fig. 5, a partial region of the
In order to form a retardation film on the upper side of the organic light-emitting layer in the organic EL display device, it is preferable to expose the region of the coating film on the upper side of the organic light-emitting layer. In fig. 5, the exposed portion of the coating film coincides with the region of the coating film located above the organic light-emitting layer. In addition, in order not to form a retardation film on a connection terminal included in the organic EL display element, it is preferable not to expose a coating film on the connection terminal. That is, in this step, it is preferable that at least a region of the coating film located above the organic light-emitting layer in the organic EL display element is exposed, and a region of the coating film located above the connection terminal in the organic EL display element is not exposed.
The kind of light at the time of exposure is not particularly limited, but ultraviolet light is preferable.
The method of exposure is not particularly limited, and for example, a method of exposing a coating film through a mask having a predetermined opening is exemplified.
Illumination during exposureThe dose is not particularly limited, but is preferably 10mJ/cm2～50J/cm2More preferably 20mJ/cm2～5J/cm2. Further, the polymerization reaction may be carried out under heating to promote the polymerization reaction.
Depending on the type of crosslinkable group, the crosslinkable group may be reacted by performing step 3. For example, when the crosslinkable group is an acryloyl group or a methacryloyl group and the radical polymerization reaction is performed by exposure to light, the crosslinkable group is also reacted.
(step 4)
Step 4 is a step of developing the exposed coating film to form a retardation film on the organic EL display device. Preferably, by performing this step, as shown in fig. 6, only the exposed region remains, and in particular, a retardation film 40 (a retardation film for an organic EL display element) is formed on the organic EL display element 32 above the organic light-emitting layer (not shown).
In addition, as described above, by leaving the area of the coating film located on the connection terminal of the organic EL display element unexposed, the coating film in the area can be removed in this step, and a retardation film can be formed on the connection terminal.
The type of the developing solution used for development is not particularly reduced, and an optimum developing solution (for example, an alkali developing solution or a developing solution containing an organic solvent) is selected depending on the type of the coating film. Among them, an alkali developing solution is preferable from the viewpoint of more excellent removal of the coating film.
The alkali developing solution may be an aqueous solution containing an alkali. Examples of the alkali developer include an aqueous alkali solution containing a quaternary ammonium salt typified by tetramethylammonium hydroxide, an inorganic base, a primary amine, a secondary amine, a tertiary amine, an alcohol amine, or a cyclic amine. Among them, as the alkali developing solution, an aqueous solution of a quaternary ammonium salt represented by tetramethylammonium hydroxide (TMAH) is preferable. An appropriate amount of an alcohol and/or a surfactant may be added to the alkali developing solution. The alkali concentration of the alkali developing solution is preferably 0.1 to 20 mass%. The pH of the alkali developing solution is preferably 10.0 to 15.0.
The method of the development treatment is not particularly limited as long as the exposed coating film can be brought into contact with a developer, and examples thereof include a method of applying a developer to a coating film and a method of immersing a laminate having a coating film in a developer.
Further, after the development, a rinsing process may be performed using a rinse liquid, if necessary. The rinse liquid may be pure water.
If necessary, the coating film subjected to the development treatment may be subjected to a heating treatment. By performing heat treatment (post-baking treatment), the crosslinkable groups are reacted, and the chemical resistance of the retardation film can be improved. In addition, as described above, when the crosslinkable group and the hydrophilic group can be reacted by heating, the treatment is performed to react the crosslinkable group and the hydrophilic group.
The temperature of the heat treatment is not particularly limited, but is preferably 70 to 250 ℃ and more preferably 80 to 200 ℃. The time of the heat treatment is not particularly limited, but is preferably 5 to 180 minutes, more preferably 10 to 120 minutes.
By the above method, the retardation film for the organic EL display element can be formed at a predetermined position of the organic EL display element.
The retardation film for an organic EL display element formed using the composition of the present invention is not particularly limited in-plane retardation, and an optimum value is selected depending on the application used. Among them, from the viewpoint of use as a retardation film of a circularly polarizing plate described later, the retardation film is preferably a λ/4 plate or a λ/2 plate.
A λ/4 plate (a plate having a λ/4 function) is a plate having a function of converting linearly polarized light of a certain specific wavelength into circularly polarized light (or converting circularly polarized light into linearly polarized light). More specifically, the plate exhibits an in-plane retardation of λ/4 (or an odd multiple thereof) at a predetermined wavelength λ nm.
Among them, from the viewpoint of more excellent functions as a circularly polarizing plate, the in-plane retardation Re (550) at a wavelength of 550nm is preferably 100 to 200nm, more preferably 120 to 160 nm.
The λ/2 plate is an optically anisotropic layer having an in-plane retardation Re (λ) at a specific wavelength λ nm satisfying Re (λ) ≈ λ/2. Among them, the in-plane retardation Re (550) at a wavelength of 550nm is preferably 210 to 300 nm.
The retardation film for an organic EL display element formed using the composition of the present invention preferably exhibits reverse wavelength dispersibility (a property in which in-plane retardation increases as the measurement wavelength increases).
In addition, a plurality of retardation films for organic EL display elements may be laminated by performing the above method a plurality of times. That is, only 1 layer of retardation film may be formed, or 2 or more layers may be formed, on a predetermined position of the organic EL display element by using the composition of the present invention. When 2 or more layers are formed, for example, a laminate of a λ/2 plate exhibiting positive wavelength dispersion characteristics and a λ/4 plate exhibiting positive wavelength dispersion characteristics and a laminate of a λ/4 plate exhibiting reverse wavelength dispersion characteristics and a positive C plate are given.
In addition, a retardation film having other functions can be formed by adding an additive such as a coloring matter to the composition of the present invention within a range not departing from the gist of the present invention.
For example, a retardation film exhibiting a twisted nematic phase or a cholesteric phase may be provided as the retardation film. Such a retardation film provides, for example, a function of rotating the polarization axis as a light-rotating layer or an effect of improving the brightness or the color reproducibility as a wavelength-selective reflection film. Such a retardation film can be obtained by adding a known chiral agent to the composition of the present invention. Also, the phase difference film exhibiting a cholesteric phase can also be used as a C plate with respect to light of a specific wavelength (nx ≈ ny < nz or nx ≈ ny > nz).
Further, when the retardation film contains various pigments, the color reproducibility can be improved, or a visual effect can be imparted to the retardation film to improve the display performance. Such a retardation film containing a dye is obtained by adding a dye to the composition of the present invention. For example, a dye having an absorption peak at a wavelength of 480 to 520nm or a wavelength of 580 to 620nm is useful for expanding a color reproduction region.
In addition, in particular, when a dichroic dye is used as the dye and the dichroic dye is aligned by the alignment of the liquid crystal compound of the composition of the present invention, anisotropy (in-plane direction or oblique viewing direction) of light absorption characteristics can be imparted and display performance can be improved.
< organic EL display device >
By the above method, an organic EL display device including an organic EL display element and the retardation film for an organic EL display element disposed on the organic EL display element is manufactured. The retardation film for an organic EL display element is preferably disposed so as to be in direct contact with the organic EL display element.
The organic EL display device preferably further includes a polarizer on the retardation film for the organic EL display element. For example, when the retardation film for organic EL display element functions as a λ/4 plate, the polarizer and the retardation film for organic EL display element are combined to function as a circularly polarizing plate. When the retardation film for organic EL display element and the polarizer are laminated as λ/4 plates, the angle formed by the in-plane slow axis of the retardation film for organic EL display element and the absorption axis of the polarizer is preferably adjusted to 45 ± 10 °.
By disposing a circularly polarizing plate on the organic EL display element, reflection of external light is prevented.
The polarizer may be a member (linear polarizer) having a function of converting light into specific linearly polarized light, and for example, an absorption type polarizer may be mentioned.
Examples of the absorption type polarizer include an iodine type polarizer, a dye type polarizer using a dichroic dye, and a polyene type polarizer. The iodine-based polarizer and the dye-based polarizer can be applied to both a coated polarizer and a stretched polarizer. Among them, a polarizer prepared by adsorbing iodine or a dichroic dye to polyvinyl alcohol and stretching is preferable.
Further, as a method for obtaining a polarizer by stretching and dyeing a laminated film in which a polyvinyl alcohol layer is formed on a substrate, there are methods described in japanese patent No. 5048120, japanese patent No. 5143918, japanese patent No. 5048120, japanese patent No. 4691205, japanese patent No. 4751481 and japanese patent No. 4751486, and known techniques related to these polarizers can be preferably used.
Among them, from the viewpoint of operability, the polarizer preferably contains a polyvinyl alcohol resin (containing-CH as a repeating unit)2-CHOH-polymer, particularly preferably at least 1 selected from the group comprising polyvinyl alcohol and ethylene-vinyl alcohol copolymer. ) The polarizer of (4).
The thickness of the polarizer is not particularly limited, but is preferably 35 μm or less, and more preferably 3 to 25 μm, from the viewpoint of excellent handling properties and excellent optical properties.
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