Ink composition with high refractive index and use thereof

Abstract

The present application discloses an ink composition with high refractive index, comprising 10 parts by mass of a block structure shown in formula (1), 40-60 parts by mass of modified nano zirconium oxide, 30-60 parts by mass of a structure shown in formula (2), and 1-5 parts by mass of an initiator. The ink composition has lower viscosity, higher light transmittance, and the hardened film formed by the ink composition has higher refractive index.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical materials. More particularly, the present application relates to an ink composition with high refractive index and its application. BACKGROUND

[0002] An organic light emitting diode (OLED) is a next-generation display device that utilizes organic compounds for self-emission, and has various advantages, for example, it has a very fast response speed, and does not require a backlight device that can reduce color sensitivity due to self-emission. Therefore, OLEDs are widely used from large displays for televisions to small displays for mobile devices.

[0003] As an ink composition for OLEDs, a conventional ultraviolet light-curable ink composition does not contain nanoscale oxide particles, and the refractive index of the cured adhesive layer is significantly different from the refractive index of the optical element to be bonded, and when light passes through these multilayer optical devices, severe total reflection occurs, thereby greatly reducing the light extraction efficiency. Directly screening higher refractive index light-curable monomers or resins and other organic materials can only slightly increase the refractive index of the adhesive layer to 1.58-1.63, and can easily cause other problems.

[0004] At present, the developed ultraviolet light-curable ink composition containing nanoscale oxide particles has a refractive index of 1.63-1.68, on the one hand, the nanoscale oxide particles are not uniformly distributed in the ink composition or the compatibility needs to be further improved, on the other hand, the particle size of the nanoscale oxide particles is higher than 20 nm, which can significantly reduce the light transmittance of the ink composition and the cured adhesive layer. SUMMARY

[0005] An object of the present application is to solve at least the above problems and provide at least the advantages to be described later.

[0006] Another object of the present application is to provide an ink composition with high refractive index, which is prepared by using a copolymerized form of carbazole, modified nanoscale zirconium oxide, and an allyl benzoate monomer as reaction raw materials. By introducing these reaction raw materials into the ink composition for OLED packaging, the present application not only has good packaging effect, but also has high refractive index and high light transmittance, etc., thereby significantly improving the light extraction efficiency of the light extraction structure, and making the OLED display screen have higher display brightness.

[0007] In order to achieve these objects and other advantages according to the present application, a first aspect of the present application provides an ink composition with high refractive index, comprising 10 parts by mass of a block structure represented by formula (1), 40-60 parts by mass of modified nanoscale zirconium oxide, 30-60 parts by mass of a structure represented by formula (2), and 1-5 parts by mass of an initiator.

[0008]

[0009] wherein R1 is a C1-C6 alkyl group or a C1-C6 alkoxy group; X1, X2 and X3 are each independently hydrogen, a methyl group, an ethyl group, a methoxy group or a hydroxyl group, X4 is a carboxyl group or a phosphate group, n is an integer of 0-5, x and y are in the range of 0-1, and x+y=1.

[0010] Specifically, the modified nano-zirconium oxide is modified from the structure shown in formula (3);

[0011]

[0012] In formula (3), R1 is a C1-C6 alkyl group or a C1-C6 alkoxy group, and R2 is a C1-C6 alkyl group.

[0013] Specifically, the modified nano-zirconium oxide is prepared by adding a modifier into a nano-zirconium oxide particle solution dropwise;

[0014] The modifier is prepared by dissolving the structure shown in formula (3) in an alcohol solvent and water;

[0015] The nano-zirconium oxide particle is prepared by adding a zirconium precursor into an alcohol solvent and then reacting in a constant-temperature and constant-pressure autoclave.

[0016] Preferably, the content of the modified nano-zirconium oxide and the block structure shown in formula (1) is between 50-60wt%.

[0017] Preferably, the block structure shown in formula (1) is prepared by copolymerization of the structures shown in formula (4) and formula (5);

[0018] X4 is a carboxyl group, and the molar ratio of the structure shown in formula (2) to the structure shown in formula (4) is 4.5-6.5:1;

[0019]

[0020] Specifically, the viscosity of the ink composition at 25℃ is 20-30cp, the refractive index of the hardened film formed by hardening the ink composition is above 1.72, and the light transmittance of the hardened film formed by hardening the ink composition is above 95%.

[0021] Preferably, the ink composition further comprises 1-5 parts by mass of the structure shown in formula (6):

[0022]

[0023] Preferably, the ink composition further comprises 1-5 parts by mass of a structure represented by formula (7):

[0024]

[0025] The second aspect of the present application provides a hardened film obtained by curing the ink composition provided by the first aspect.

[0026] The third aspect of the present application provides a light emitting element comprising a hardened product of the ink composition provided by the first aspect.

[0027] The present application has at least the following advantages:

[0028] 1. The monomer of the structure represented by formula (2) is beneficial to the uniform dispersion and mutual solubility of the block structure represented by formula (1) and the modified nano zirconium oxide, and can adjust the viscosity of the ink composition to be suitable for the inkjet printing process, and the obtained ink has a clear and transparent appearance, low viscosity, and a high light transmittance of the cured film layer;

[0029] 2. The present application synthesizes zirconium oxide particles with a particle size of less than 10 nm by a hydrothermal method, and then modifies the nano zirconium oxide by dropwise adding a compound represented by formula (3), thereby increasing the solubility of the zirconium oxide and maintaining the high refractive index of the modified zirconium oxide;

[0030] 3. The sum of the content of the modified nano zirconium oxide and the block structure represented by formula (1) is between 50-60wt%, which can make the light transmittance of the hardened product reach a relatively optimal effect;

[0031] 4. Controlling the molar ratio of the structure represented by formula (2) and the structure represented by formula (4) can make the ink composition have a lower hardness.

[0032] Other advantages, objects, and features of the present application will be apparent from the following description, and will be understood by those skilled in the art through a study of the present application. DETAILED DESCRIPTION

[0033] The present application provides an ink composition with high refractive index, comprising 10 parts by mass of a block structure represented by formula (1), 40-60 parts by mass of modified nano zirconium oxide, 30-60 parts by mass of a structure represented by formula (2), and 1-5 parts by mass of an initiator.

[0034]

[0035] In the formula, R1 is a C1-C6 alkyl group or a C1-C6 alkoxy group; X1, X2, and X3 are each independently hydrogen, a methyl group, an ethyl group, a methoxy group, or a hydroxyl group, X4 is a carboxyl group or a phosphate group, n is an integer of 0-5, the values of x and y are in the range of 0-1, and x+y=1.

[0036] R1 may be, for example, a methyl group, an ethyl group, a propyl group, a n-butyl group, an isobutyl group, a methoxy group, an ethoxy group, or a propoxy group, and the like.

[0037] The synthesis method of the block structure shown in formula (1) is specifically as follows: dissolving the structure shown in formula (4) and the structure shown in formula (5) in a first solvent, warming, adding an azo initiator, continuously reacting, and precipitating to obtain the block structure shown in formula (1);

[0038]

[0039] Specifically, the warming temperature is 60-120℃, preferably 60-100℃, and further preferably 60-90℃; the continuous reaction time is 24-36h; after the reaction is completed, a non-polar solvent such as n-hexane is used to precipitate the sediment, the solid is filtered, and after multiple washing and filtering, the solid is dried in a vacuum drying oven; the vacuum drying temperature should not be too high, and 60-100℃ is appropriate, and preferably about 60℃;

[0040] When the azo initiator is added, the azo initiator is first dissolved in the solvent, and then slowly added dropwise; the dropwise adding time is determined according to the amount, and generally takes 0.5-2h.

[0041] The first solvent is cyclohexane, methylcyclohexane, toluene, N-methylmorpholine, o-xylene, m-xylene, or p-xylene, anisole, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, diisobutyl ether, or a mixture of these compounds. The solvent used in the present application can be used alone or in combination of two or more.

[0042] In the present application, the synthesis method of the modified nano zirconium oxide is specifically as follows:

[0043] The zirconium precursor is added to an alcohol solvent, and reacted at a constant temperature in an autoclave, cooled, separated, and dried to obtain nano zirconium oxide particles;

[0044] The structure shown in formula (3) is added to an alcohol solvent and water to configure a modifier;

[0045] The nano zirconium oxide particles are dispersed in ethyl benzoate to form a nano zirconium oxide dispersion liquid, warmed, the modifier is added dropwise to the nano zirconium oxide dispersion liquid to react, precipitated, filtered and dried to obtain the modified nano zirconium oxide;

[0046]

[0047] In formula (3), R1 is a C1-C6 alkyl group or a C1-C6 alkoxy group, and R2 is a C1-C6 alkyl group; R2 may be, for example, a methylene group, an ethylene group, or a propylene group, and the like.

[0048] Specifically, the rotation speed in the autoclave is 200-300 rpm, the constant temperature reaction temperature is 200-300 DEG C, and the preferred reaction temperature is 220-280 DEG C; the reaction time is 48-96 h, preferably 60-80 h; the separation uses centrifugal separation;

[0049] The drying uses vacuum drying, and the drying temperature is 60-80 DEG C;

[0050] After the nano zirconium oxide dispersion is formed, the temperature is raised to 80-120 DEG C for reaction;

[0051] It should be noted that the modifier is added dropwise under rapid stirring, and after the reaction is completed, the specific steps for precipitation are to pour the reaction mixture after rapid stirring reaction into n-hexane for precipitation, wash the precipitate multiple times, filter, and then place it in an oven for drying;

[0052] The alcohol solvent can also be methanol, ethanol, n-butanol, benzyl alcohol, ethylene glycol, etc.

[0053] In the present application, as a preferred embodiment, the sum of the modified nano zirconium oxide and the block structure shown in formula (1) is between 50-60 wt%. The block structure shown in formula (1) and the modified nano zirconium oxide can achieve a better effect on the light transmittance of the hardened material in this mass ratio range. It should be noted that the sum of the modified nano zirconium oxide and the block structure shown in formula (1) is between 50-60 wt% of the sum of the content of the block structure shown in formula (1), the modified nano zirconium oxide, and the structure shown in formula (2).

[0054] In the present application, in the structure of formula (2), X4 is preferably a carboxyl group, and when X4 is a carboxyl group, the molar ratio of the structure shown in formula (2) to the structure shown in formula (4) is 4.5-6.5:1; limiting the molar ratio of the structure shown in formula (2) to the structure shown in formula (4) is mainly used to control the amount of carboxyl groups and carbazole, and this amount range can make the ink composition have lower hardness.

[0055] In the present application, as a polymerization monomer of the ink composition, the ink composition further includes 1-5 parts by mass of the structure shown in formula (6); adding the compound of the structure shown in formula (6) can further improve the refractive index of the hardened film;

[0056]

[0057] In the present application, as a polymerization monomer of the ink composition, the ink composition further includes 1-5 parts by mass of the structure shown in formula (7), and adding the compound of the structure shown in formula (7) can further improve the refractive index of the hardened film;

[0058]

[0059] As the photoinitiator of the ink composition of the present application, the photoinitiator is preferably a phenylphosphine compound, and the phenylphosphine compound is preferably trimethylbenzoyl-diphenylphosphine oxide or trimethylbenzoyl phenyl phosphonic acid ethyl ester.

[0060] The phenylphosphine compound can also be methyl isobutyryl phenyl phosphonate, methyl neopentanoyl phenyl phosphonate, methyl 2-ethylhexanoyl phenyl phosphonate, isopropyl neopentanoyl phenyl phosphonate, bis(2,6-dichlorobenzoyl)phenyl phosphine oxide, bis(2,6-dichlorobenzoyl)-2,5-dimethylphenyl phosphine oxide, bis(2,6-dichlorobenzoyl)-4-ethoxyphenyl phosphine oxide, bis(2,6-dichlorobenzoyl)-4-propylphenyl phosphine oxide, bis(2,6-dichlorobenzoyl)-2-naphthyl phosphine oxide, bis(2,6-dichlorobenzoyl)-1-naphthyl phosphine oxide, bis(2,6-dichlorobenzoyl)-4-chlorophenyl phosphine oxide.

[0061] In the present application, the block structure represented by formula (1), the modified nano zirconium oxide, the structure represented by formula (2), and the photoinitiator are added to a light-shielded reaction vessel, stirred at room temperature, filtered using a 0.45 um syringe filter, and an ink composition having a high refractive index is obtained.

[0062] The ink composition of the present application, which can be determined by gel permeation chromatography, can be converted by using a standard polystyrene standard curve, and the weight average molecular weight converted by polystyrene is preferably 10,000 to 100,000, more preferably 15,000 to 100,000, and further preferably 20,000 to 50,000. When the weight average molecular weight of the resin is greater than 10,000, the stress after curing can be sufficiently reduced. When the weight average molecular weight of the resin is less than 100,000, the solubility in a solvent is further improved, the viscosity of the solution is reduced, and the coating workability can be further improved.

[0063] The ink composition of the present application, which is copolymerized by the structure represented by formula (1), the modified nano zirconium oxide, and the block structure represented by formula (2), has a viscosity of 20 to 30 cp at 25°C, and the viscosity of the ink composition is suitable for the inkjet printing process.

[0064] The cured film formed by hardening the ink composition of the present application has a refractive index of 1.72 or more, and the cured film formed by hardening the ink composition has a light transmittance of 95% or more.

[0065] The present application provides a cured film that can be used as an encapsulation film for an organic light emitting device, and the encapsulation film is cured by irradiating the ejected ink composition with ultraviolet rays.

[0066] The encapsulation film includes an encapsulation composition for inkjet printing having a high refractive index, which is coated and cured on an organic layer of an organic light emitting device.

[0067] The thickness of the encapsulation film for the organic light emitting device can be 10 to 25 μm, preferably 10 to 20 μm.

[0068] If the thickness of the encapsulation film is thin, at a level of less than 10 μm, the surface is not smooth, and half of the particles are exposed, resulting in unevenness. If the thickness of the encapsulation film exceeds 25 μm, there is a problem in that the haze can increase.

[0069] The encapsulation film for the organic light emitting device can have a light transmittance of 90% or more and a haze of 20% or less, and the encapsulation film meeting the parameters is measured at a thickness of 25 μm.

[0070] Since the encapsulation film for the organic light emitting device according to the present application needs to have a function different from that of the encapsulation material of the LCD light diffusion material, preferably, the light transmittance of the encapsulation film is 90% or more. If the light transmittance is less than 90%, the film is not transparent, resulting in a problem of top emission.

[0071] According to the present application, there is provided an organic light emitting element formed by curing an ink composition.

[0072] The light emitting element according to the present application, i.e., an organic light emitting diode display, includes a substrate, an organic light emitting diode fixed to the substrate, an inorganic layer encapsulating the organic light emitting diode, and an encapsulation film layer stacked on the inorganic layer, the encapsulation film layer being alternately stacked with the inorganic layer to form a thin film encapsulation structure, and water and oxygen are effectively prevented from penetrating the thin film layer through the multi-layer stacked thin film encapsulation structure, thereby protecting the device.

[0073] The present application will be further described in detail with reference to the following examples, which are presented for the purpose of illustration only.

[0074] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials described are all commercially available unless otherwise specified.

[0075] <Synthesis Example 1>

[0076] Synthesis of the block structure A1 represented by Formula (1):

[0077] Dissolve 10 g of N-vinylcarbazole and 2 g of allyl benzoate in 50 ml of toluene, after warming to 70°C, add a mixture of 1 g of azobisisobutyronitrile and 10 ml of toluene dropwise while stirring, the dropwise process lasts for 30 min, then continue to react for 24 h, the product is precipitated with 300 g of n-hexane, after filtration, multiple washing and filtration, and vacuum drying at 60°C for 24 h, finally 9.8 g of brown red powder solid A1 is obtained, with a yield of 81.7%.

[0078] <synthesis example 2>

[0079] Synthesis of modified nano zirconium oxide:

[0080] Put 33.3 g of zirconium n-propyl alcohol and 500 ml of benzyl alcohol into a 1 L autoclave, rotate at 200 rpm, warm up to 240°C, react for 72 h, after cooling to room temperature, a white turbid emulsion is obtained, after centrifugal separation and vacuum drying, 12.4 g of nano zirconium oxide particles are obtained.

[0081] First, 2 g of monoallyl phthalate and 4 g of ethanol and 4 g of water are mixed to prepare a modifier;

[0082] Then, 12 g of nano zirconium oxide particles and 200 g of ethyl benzoate are added to a 1 L four-necked flask, stirred and dispersed, then the reaction temperature is warmed to 90°C, and the modifier is added to the four-necked flask at a rate of 1 drop per second under rapid stirring, after the addition is completed, stirring is continued for 6 h, then the reacted solution is precipitated in 1000 g of n-hexane, after multiple washing and filtration, it is placed in a vacuum oven for drying for 24 h, to obtain the final product modified nano zirconium oxide B1.

[0083] <comparative synthesis example 1>

[0084] Put 33.3 g of zirconium n-propyl alcohol into 500 ml of water, adjust to acidic with hydrochloric acid, then add to a 1 L autoclave, rotate at 200 rpm, warm up to 240°C, react for 72 h, after cooling to room temperature, a white suspension is obtained, after centrifugal separation and vacuum drying, nano zirconium oxide solid B'1 is obtained.

[0085] <example 1>

[0086] In a 250 mL brown glass bottle, add 10 g of A1, 50 g of B1, 35 g of monoallyl phthalate (C1), and 5 g of a photoinitiator (2,4,6-trimethylbenzoyl-diphenyl phosphine oxide), stir at room temperature for 1 h, then filter with a 0.45 um needle filter to obtain ink composition 1.

[0087] The ink composition was printed on the surface of an ITO substrate in a size of 16.5 cm x 7.5 cm x 10 um (length x width x thickness) by inkjet printing, and then cured by ultraviolet curing for 10 seconds using a UV curing device of 1000 mW / cm 2 to obtain a hardened film.

[0088] Examples 2 to 8 and Comparative Examples 1 to 5 were prepared according to the preparation method of Example 1. The mass parts of the different components in Examples 1 to 8 and Comparative Examples 1 to 5 are recorded in Table 1. Comparative Examples 1-2 used the nano-zirconium oxide of No. B'1 synthesized in Comparative Synthesis Example 1.

[0089] The properties of the ink compositions and hardened films described above were evaluated, and the results are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] <Method of Evaluation>

[0094] 1. Viscosity

[0095] The viscosity of the ink compositions of Examples 1-8 and Comparative Examples 1-5 was measured using a rheometer. The specific operation method was as follows: using a cone-plate clamp, the test temperature was 35°C, and the shear test was performed in flow scanning mode; the ink composition was loaded to the center of the Peltier plate, and the mold was used to fix the center of the circle to ensure that the ink composition was as much as possible in the center; and the viscosity was obtained by calculating the ratio of stress to shear rate.

[0096] 2. Light transmittance

[0097] The hardened films formed from the ink compositions of Examples 1-8 and Comparative Examples 1-5 were tested, and the light transmittance in the visible light range was tested using a spectrophotometer UV-1650PC manufactured by Shimadzu Corporation.

[0098] 3. Refractive index

[0099] The hardened films formed from the ink compositions of Examples 1-8 and Comparative Examples 1-5 were tested, and the refractive index of the hardened films was measured using an Abbe refractometer (sodium D line (589 nm), 25°C). When measuring the refractive index of the film sheet, a matching oil was used for measurement.

[0100] 4. Shore A hardness

[0101] The hardened films formed from the ink compositions of Examples 1-8 and Comparative Examples 1-5 were tested for Shore A hardness (room temperature) of the hardened film sheet according to ASTM D2240 using a Type A durometer.

[0102] While embodiments of the application have been disclosed in connection with the above specification and drawings this description is not intended to limit the scope of the application and many modifications, enhancements, substitutes, changes and alterations of the methods and compositions described herein can become apparent to those skilled in the art without departing from the spirit and scope of the application as set forth in the following claims.

Claims

1. An ink composition having a high refractive index, characterized by, The ink composition comprises 10 parts by mass of a block structure represented by formula (1), 40-60 parts by mass of modified nano zirconium oxide, 30-60 parts by mass of a structure represented by formula (2), and 1-5 parts by mass of an initiator. In the formula, R1 is C1-C6 alkyl or C1-C6 alkoxy; X1, X2, and X3 are each independently hydrogen, methyl, ethyl, methoxy, or hydroxyl, X4 is a carboxyl or phosphoric acid group, and n is an integer of 0-5; the synthesis method of the block structure is: dissolving 10 g of N-vinylcarbazole and 2 g of allyl benzoate in a first solvent, warming, adding an azo initiator, continuously reacting, and precipitating; the modified nano zirconium oxide is modified from a structure represented by formula (3). In formula (3), R1 is C1-C6 alkyl or C1-C6 alkoxy, and R2 is C1-C6 alkyl.

2. The ink composition with high refractive index according to claim 1, wherein, The modified nano zirconium oxide is prepared by adding a modifier dropwise into a nano zirconium oxide dispersion liquid; The modifier is prepared by dissolving a structure represented by formula (3) in an alcohol solvent and water; The nano zirconium oxide dispersion liquid is prepared by adding a zirconium precursor into an alcohol solvent, then placing the mixture in an autoclave for constant-temperature and constant-pressure reaction, and then dispersing.

3. The ink composition with high refractive index according to claim 1, wherein The sum of the content of the modified nano zirconium oxide and the block structure represented by formula (1) is between 50-60 wt%.

4. The ink composition with high refractive index according to claim 1, wherein The viscosity of the ink composition at 25°C is 20-30 cp, the refractive index of a hardened film formed by hardening the ink composition is 1.72 or more, and the light transmittance of the hardened film formed by hardening the ink composition is 95% or more.

5. The ink composition with high refractive index according to claim 1, wherein The ink composition further comprises 1-5 parts by mass of a structure represented by formula (6):

6. The ink composition with high refractive index according to claim 1, wherein The ink composition further comprises 1-5 parts by mass of a structure represented by formula (7):

7. A hardened film characterized by, The hardened product of the ink composition of any one of claims 1-6.

8. A light emitting element characterized by comprising: The hardened product of the ink composition of any one of claims 1-6.

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