WO2024192798A1 - Photocurable encapsulation ink and display apparatus - Google Patents

Abstract

The present invention relates to the technical field of photoelectric material applications, and specifically relates to a photocurable encapsulation ink and a display apparatus. The photocurable encapsulation ink is made of a resin that may be rich in a large number of groups that have hydrophilicity, adhesion, and active hydrogen donors, such as ether and amide groups. The photocurable encapsulation ink has excellent encapsulation characteristics, has both rigidity and flexibility, and has excellent fatigue resistance and yellowing resistance under alternating stress, and thus can be applied to flexible or foldable apparatuses.

Description

Photocurable packaging ink and display device Technical Field

The invention belongs to the field of photoelectric material application technology, and specifically relates to a photocurable packaging ink and a display device.

Background Art

Thin film encapsulation is one of the key processes that affect the characteristics of optoelectronic components. It blocks moisture or air that causes fatal defects such as insufficient brightness and black spots in optoelectronic components, and prolongs the permeation path of air and moisture, thereby greatly extending the service life of optoelectronic components such as flexible displays, chips, and sensors. However, in the prior art, thin film encapsulation materials such as flexible panels require not only excellent water and oxygen barrier properties, but also are usually required to withstand stress changes without being damaged during repeated bending. In addition, thin film encapsulation also has yellowing phenomena under the effects of heat, oxygen, stress, trace moisture, impurities, improper processes, etc. Therefore, how to design a good thin film encapsulation material so that the encapsulation film takes into account water and oxygen barrier properties, flexibility, yellowing resistance and other properties is crucial to improving the quality of optoelectronic components such as display devices, integrated circuits, and lighting.

Summary of the invention

The object of the present invention is to provide a photocurable packaging ink with excellent comprehensive performance, which has high water and oxygen barrier, is anti-bending, is resistant to yellowing and can be prepared by inkjet printing.

The first aspect of the present invention provides a photocurable packaging ink, comprising:

The ether unsaturated resin monomer has a structure represented by the following chemical formula 1:

and a photoinitiator;

Chemical formula 1

Wherein, Ar ₁ and Ar ₂ are selected from: unsubstituted or hydroxy-substituted C ₁ -C ₉ alkyl, unsubstituted or C ₁ -C ₉ alkyl, C ₁ -C ₄ alkoxy phenyl;

Ar ₃ is selected from unsubstituted or hydroxy-substituted C ₁ -C ₄ alkylene groups;

X ₁ , X ₂ , and X ₃ are respectively O, NH or N(R ₄ ), and R ₄ is a C ₁ -C ₆ alkyl group;

R ₁ , R ₂ , and R ₃ are each H or a C ₁ -C ₆ alkyl group;

a and b are integers from 0 to 7 respectively, and a+b≤8;

c, d, and e are 0 or 1 respectively, and c+d+e≥1.

According to the above technical scheme, Ar ₁ is selected from: unsubstituted C ₁ -C ₉ straight-chain alkane group, C ₁ -C ₆ straight-chain alkane group substituted by 1 methyl or ethyl group, or, unsubstituted or phenyl substituted by 1 C ₁ -C ₉ straight-chain alkane group or methoxy group; Ar ₂ is selected from C ₁ -C ₃ straight-chain alkane group substituted by 0-1 methyl, ethyl or hydroxyl group, phenyl, or benzyl group; Ar ₃ is selected from C ₁ -C ₃ straight-chain alkane group substituted by 0-1 methyl, ethyl or hydroxyl group; R ₁ , R ₂ , R ₃ are selected from hydrogen, methyl, ethyl, n-propyl, isopropyl, tert-butyl or cyclohexyl respectively.

The photocurable packaging ink provided by the above technical solution may use a resin rich in a large number of ether, amide groups and other groups that have hydrophilicity, adhesion and active hydrogen donor properties, which endows the composition with high water solidity and excellent oxygen inhibition performance, good UV curing effect, and effectively prevents water and oxygen that penetrate into the device from further penetrating into the organic material through the molecular network cross-linking structure of the composition to affect the photoelectric properties of the device, and has excellent packaging characteristics. In addition, the resin used may also be an aryl alkyl ether resin, which destroys the formation of large conjugated systems such as biphenyl, has both rigidity and flexibility, and has excellent fatigue resistance and yellowing resistance under alternating stress, and can be applied to flexible or foldable devices. It has excellent application prospects in terminal applications such as foldable TVs, mobile phones, and wearable devices.

According to the above technical solution, in the photocurable packaging ink, the ether unsaturated resin monomer contains one or two aromatic ether resins, that is, the compound of formula 1 wherein Ar ₁ and/or Ar ₂ is a phenyl group that is unsubstituted or substituted by a C ₁ -C ₉ alkyl group or a C ₁ -C ₄ alkoxy group.

According to the above technical solution, in the photocurable packaging ink, the ether unsaturated resin monomer contains one or two alkyl ether resins, that is, Ar ₁ and Ar ₂ are both unsubstituted or hydroxyl-substituted C ₁ -C ₉ alkyl compounds of formula 1.

According to the above technical scheme, the photocurable packaging ink prepared by selecting any one of the aromatic ether unsaturated resin monomers or alkyl ether unsaturated resin monomers provided by the present invention, that is, the photocurable packaging ink containing alkane unsaturated resin monomers or biphenyl unsaturated resin monomers with a conventional low hygroscopic design, the combination of the two can further adjust the viscosity of the photocurable packaging ink, making it more suitable for film preparation, and at the same time, ensuring that the photocurable packaging ink has excellent comprehensive properties of high water and oxygen barrier, anti-bending, and anti-yellowing.

According to the above technical scheme, the photocurable packaging ink contains 45%-65% (by weight) of one or two compounds of formula _{1 in which Ar1 and/or Ar2 are unsubstituted or substituted by C1-C9 alkyl or C1 - C4} alkoxy, 25%-50% (by weight) of one or two compounds of formula ₁ in which Ar1 and _Ar2 are both unsubstituted or substituted by hydroxyl _C1 - _C9 alkyl, and 0.1%-10% (by weight) of a photoinitiator.

According to the above technical scheme, the compound of formula 1 is selected from the compounds represented by the following structural formula:

According to the above technical solution, the photocurable encapsulation ink further comprises one or more acrylate crosslinking agents of the general formula Ar ₄ [X ₄ OCC(R ₅ )=CH ₂ ] _f ;

Wherein, Ar ₄ is selected from unsubstituted or hydroxy-substituted C ₃ -C ₁₂ alkyl groups, C ₆ -C ₂₀ aromatic groups containing 1 to 2 phenyl groups;

X ₄ is O, NH or N(R ₆ ), R ₆ is a C ₁ -C ₆ alkyl group;

_R5 is H or methyl;

f is an integer of 1 to 6.

According to the above technical solution, in the photocurable packaging ink, _R6 is selected from: methyl, ethyl, n-propyl, isopropyl, tert-butyl or cyclohexyl.

According to the above technical solution, the photocurable packaging ink contains an acrylate crosslinking agent in which Ar ₄ is selected from unsubstituted or hydroxyl-substituted C ₃ -C ₁₂ alkane groups.

According to the above technical solution, Ar ₄ is selected from:

*The position corresponds to the connection with the X ₄ group in X ₄ OCC(R ₅ )=CH ₂ .

According to the above technical solution, the photocurable packaging ink contains 35%-65% (weight) of the ether unsaturated resin monomer, 30%-60% (weight) of an acrylate crosslinker of the general formula Ar ₄ [X ₄ OCC(R ₅ )=CH ₂ ] _f and 0.1%-10% (weight) of a photoinitiator.

According to the above technical solution, the photocurable packaging ink further comprises one or more of 0.1%-5% (by weight) of a surfactant, 0.1%-5% (by weight) of an adhesion promoter or 0.1%-5% (by weight) of a defoaming agent.

According to the above technical scheme, the photoinitiator used in the present invention can use a general photoinitiator, The general photoinitiator can usually be used for the photocurable resin composition, and specific examples include: benzoin photoinitiators, ketone photoinitiators, phosphine oxide photoinitiators, peroxide photoinitiators, and oxime ester photoinitiators.

According to the above technical scheme, the benzoin-based photoinitiator can be exemplified by: benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, benzoin dimethyl ether, benzoin diethyl ether, and the like. Examples of ketone photoinitiators include benzophenone, 4-phenylbenzophenone, p-chlorobenzophenone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-2-methyl-1-[4-(tert-butyl)phenyl]-1-propanone, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-(4-hydroxyethoxy)phenyl-1-propanone, poly[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone], bifunctional α-hydroxyketone, 4,4'-bis(diethylamino)benzophenone, 2,2-dimethoxyacetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, and 2-isopropylthioxanthone. Examples of phosphine oxide photoinitiators include triphenylphosphine oxide, (2,4,6-trimethylbenzoyl)diphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and ethyl (2,4,6-trimethylbenzoyl)phenylphosphine oxide; examples of peroxy photoinitiators include tert-butyl perbenzoate, diisopropylbenzene peroxide, and dibenzoyl peroxide; examples of oxime ester photoinitiators include 1-[4-(phenylthio)phenyl]-1,2-octanedione 2-(O-benzoyloxime), 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone 1-(O-acetyloxime), and the like.

According to the above technical scheme, the surfactants used in the present invention include but are not limited to: BYK-300, BYK301, BYK302, BYK333, BYK352, BYK358N, BYK361N, etc. commercially available from BYK Chemical Company of Germany, and KP341, KP310, KP321, etc. commercially available from Shin-Etsu Chemical Co., Ltd.

According to the above technical scheme, the adhesion promoter used in the present invention is a silane compound, including but not limited to: one or more of bis[3-(triethoxysilyl)propyl]amine, 3-(isomethacryloyloxy)propyltrimethoxysilane, and (3-mercaptopropyl)trimethoxysilane.

According to the above technical scheme, the defoaming agent used in the present invention includes but is not limited to: The products sold are BYK-057, BYK-065, BYK-066N, and the products sold by Germany's Digo are TEGO-900, TEGO-1488, etc.

According to the above technical scheme, when the acrylate crosslinking agent of the general formula Ar ₄ [X ₄ OCC (R ₅ ) = CH ₂ ] _f is not included, the preparation method of the photocurable packaging ink comprises the following steps: adding 45%-65% (weight) of one or two compounds of formula 1 in which Ar ₁ and/or Ar ₂ are unsubstituted or substituted by C ₁ -C ₉ alkyl or C ₁ -C ₄ alkoxy, 25%-50% (weight) of one or two compounds of formula 1 in which Ar ₁ and Ar ₂ are both unsubstituted or substituted by hydroxyl C ₁ -C ₉ alkyl, 0.1%-10% (weight) of photoinitiator, adding or not adding 0.1%-5% (weight) of one or more of surfactant, adhesion promoter and defoamer as needed, stirring at 25°C-60°C for 2-6h to form a uniform and transparent solution, so as to prepare the photocurable packaging ink.

According to the above technical scheme, when the acrylate crosslinking agent of the general formula Ar ₄ [X ₄ OCC(R ₅ )＝CH ₂ ] _f is contained, the preparation method of the photocurable packaging ink comprises the following steps: adding 35%-65% (by weight) of the ether unsaturated resin monomer represented by Chemical Formula 1, 30%-60% (by weight) of the acrylate crosslinking agent of the general formula Ar ₄ [X ₄ OCC(R ₅ )＝CH ₂ ] _f , 0.1%-10% (by weight) of the photoinitiator into a reaction kettle, adding or not adding 0.1%-5% (by weight) of one or more of a surfactant, an adhesion promoter, and a defoaming agent as needed, stirring at 25° C.-60° C. for 2-6 hours to form a uniform and transparent solution, thereby preparing the photocurable packaging ink.

According to the above technical scheme, the encapsulation composition can be prepared by coating, spraying, spin coating, injection, scraping, brushing, nano-imprinting, inkjet printing, screen printing or pad printing and then cured by ultraviolet light to form a shape.

The present invention also provides a display device, comprising at least a substrate and an encapsulation layer, and a light-emitting element located therebetween, wherein the cured photocurable encapsulation ink alone or in combination with at least one inorganic barrier layer alternately constitutes the encapsulation layer. According to the above technical solution, the encapsulation layer comprises: a first inorganic barrier layer, disposed on the light-emitting element; the cured photocurable encapsulation ink, disposed on the first inorganic barrier layer; and a second inorganic barrier layer, disposed on the cured photocurable encapsulation ink. On top of the light-curable encapsulation ink.

According to the above technical solution, the inorganic barrier layer is one or more of Al ₂ O ₃ , SiOx, _SiNx , _SiONx , and _SiCNx .

According to the above technical solution, the thickness of the inorganic barrier layer is 0.5 μm to 1.5 μm.

According to the above technical solution, the thickness of the cured photocurable packaging ink is 4-20 μm.

The above-mentioned photocurable encapsulation ink provided by the present invention is rich in a large number of ether, amide groups and other groups with both hydrophilicity, adhesion and active hydrogen donors, which endow the composition with high water solidity and excellent oxygen inhibition performance, good ultraviolet curing effect, and effectively prevents the water and oxygen that penetrate into the device from further penetrating into the organic material through the molecular network cross-linking structure of the composition to affect the photoelectric properties of the device, and has excellent encapsulation characteristics. Compared with the conventional comparative example 1 and comparative example 2 designed with low hygroscopicity as the concept (the water vapor permeability is much higher than the order of ^10-4g / ^m2 /day), its water vapor permeability reaches the order of ^10-4g / ^m2 /day, so it can be used alone or alternately with at least one inorganic barrier layer to form the encapsulation layer. In addition, the aryl alkyl ether resin destroys the formation of large conjugated systems such as biphenyl, has both rigidity and flexibility, and has excellent fatigue resistance and yellowing resistance under alternating stress, and can be applied to flexible or foldable devices, and has excellent application prospects in terminal applications such as flexible or foldable TVs, mobile phones, and wearable devices.

DETAILED DESCRIPTION

Below, in order to help understand the present invention, preferred embodiments are proposed. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention. If specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be obtained commercially.

The components of Examples and Comparative Examples will be described in detail below.

(A) Ether unsaturated resin monomers: (A1) 2-[2-(2-phenoxyethoxy)ethoxy]ethyl acrylate, (A2) 3-phenoxybenzyl acrylate, (A3) 2-acrylate (1,3-phenylene) bis(oxy-2,1-ethylene) ester, (A4) 4,4'-diphenyl ether diacrylate (A5) 4,4'-diphenyl ether diacrylate ether diacrylamide, (A6) 2-hydroxy-3-phenoxypropyl acrylate, (A7) 2-hydroxy-3-phenoxypropyl acrylate, (A8) hexaethylene glycol monomethyl ether acrylate, (A9) diethylene glycol 2-ethylhexyl ether methacrylate, (A10) triethylene glycol diacrylate, (A11) diacrylamide-polytriethylene glycol, (A12) glycerol trihydroxypropyl ether triacrylate;

(B) Acrylate crosslinking agent: (B1) 1,12-dodecyl glycol diacrylate, (B2) 2-([1,1'-biphenyl]-2-oxy)ethyl 2-acrylate, (B3) 1,3-adamantyl diacrylate, (B4) biphenyl-4,4'-diyl bis(oxy-2,1-ethanediyl) dimethacrylate, (B5) 1,9-bis(acryloyloxy)nonane;

(C) Photoinitiator: (C1) poly[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, (C2) 2,4,6-trimethylbenzoyl-diphenylphosphine oxide;

(D) Surfactant: (D1) BYK301 (BYK, Germany), (D2) BYK333 (BYK, Germany);

(E) Adhesion promoter: 3-(methacryloyloxy)propyltrimethoxysilane.

Example 1

40 parts by weight of (A1), 17 parts by weight of (A2), 30 parts by weight of (B1), 2 parts by weight of (C1), and 0.5 parts by weight of BYK301 surfactant were added into a reaction kettle and stirred at 25°C-60°C for 2-6 hours to form a uniform and transparent solution, thereby preparing the photocurable encapsulation ink. Examples 2 to 12 and Comparative Examples 1 to 2

The photocurable encapsulation ink was prepared in the same manner as in Example 1, except that the type and amount of each component as shown in Table 1 were used.

Table 1

Evaluation of physical properties

(1) Viscosity test: The viscosity of the encapsulation composition prepared above was tested at 25° C. using a rotational viscometer (model LV-SSR).

(2) A sample of the encapsulation composition with a thickness of 1 mm was irradiated with 395 nm ultraviolet light at 1500 mJ/ ^cm2 for 10 min in air and its curing condition was observed to evaluate the oxygen inhibition effect of the material.

(3) The encapsulation composition was prepared into a 20 μm film using an inkjet printing device, and cured by irradiating 395 nm ultraviolet light at 1500 mJ/cm ² under nitrogen conditions. The yellowness index (YI) value was measured using a yellowness index meter (model DLT-YS).

(4) On a 1.5 μm SiNx inorganic thin film, a 20 μm encapsulation composition of the above embodiment was printed using an inkjet printer to form an organic encapsulation film. The film was cured by irradiating with 395 nm ultraviolet light at 1500 mJ/ ^cm2 under nitrogen conditions. The water vapor permeability of water vapor passing through the organic encapsulation film and then the inorganic thin film was tested using a water vapor permeability meter (Model AQUATRAN 3).

(5) The encapsulation composition was prepared into a 20 μm film using an inkjet printing device, and cured by irradiating with 395 nm ultraviolet light at 1500 mJ/ ^cm2 under nitrogen conditions. The film was tested using a bending tolerance tester (Model FlexiGO) under the condition of bending 20K (200,000 times) with a bending radius of R = 1.5 mm. An optical microscope was used to check whether cracks appeared in the bending area, so as to evaluate the bending ability of the material.

The evaluation results of the physical properties of the photocurable encapsulation inks prepared in the examples and comparative examples are shown in Table 2.

Table 2

It can be seen from Table 1 and Table 2 that the above-mentioned photocurable packaging ink provided by the present invention, relative to Comparative Examples 1 and 2, is rich in a large number of ether, amide groups and other groups that have hydrophilicity, adhesion and active hydrogen donors, which endows the composition with high water solidity and excellent oxygen inhibition performance, good ultraviolet light curing effect, and effectively prevents water and oxygen that penetrate into the device from further penetrating into the organic material through the molecular network cross-linking structure of the composition to affect the photoelectric performance of the device, and has excellent packaging characteristics. In addition, the aryl alkyl ether resin destroys the formation of large conjugated systems such as biphenyl, has both rigidity and flexibility, and has excellent fatigue resistance and yellowing resistance under alternating stress, and can be applied to flexible or foldable devices, and has excellent application prospects in terminal applications such as flexible or foldable TVs, mobile phones, and wearable devices.

The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims (10)

A photocurable packaging ink, characterized in that it comprises: The ether unsaturated resin monomer has a structure represented by the following chemical formula 1: and a photoinitiator; Chemical formula 1
Wherein, Ar ₁ and Ar ₂ are selected from: unsubstituted or hydroxy-substituted C ₁ -C ₉ alkyl, unsubstituted or C ₁ -C ₉ alkyl, C ₁ -C ₄ alkoxy phenyl; Ar ₃ is selected from unsubstituted or hydroxy-substituted C ₁ -C ₄ alkylene groups; X ₁ , X ₂ , and X ₃ are respectively O, NH or N(R ₄ ), and R ₄ is a C ₁ -C ₆ alkyl group; R ₁ , R ₂ , and R ₃ are each H or a C ₁ -C ₆ alkyl group; a and b are integers from 0 to 7 respectively, and a+b≤8; c, d, and e are 0 or 1 respectively, and c+d+e≥1. The photocurable packaging ink according to claim 1, characterized in that: the ether unsaturated resin monomer contains one or two compounds of formula 1 in which _Ar1 and/or _Ar2 are unsubstituted or substituted phenyl groups with _C1 - _C9 alkyl groups or _C1 - _C4 alkoxy groups. The photocurable packaging ink according to claim 1, characterized in that the ether unsaturated resin monomer contains one or both of the compounds of formula 1 in which Ar ₁ and Ar ₂ are both unsubstituted or substituted with hydroxyl groups and are C ₁ -C ₉ alkyl groups. The photocurable packaging ink according to claim 1, characterized in that: The compound of formula 1 is selected from the compounds represented by the following structural formula:



The photocurable packaging ink according to claim 1, characterized in that the photocurable packaging ink further comprises one or more acrylate crosslinking agents of the general formula Ar ₄ [X ₄ OCC(R ₅ )＝CH ₂ ] _f ; Wherein, Ar ₄ is selected from unsubstituted or hydroxy-substituted C ₃ -C ₁₂ alkyl groups, C ₆ -C ₂₀ aromatic groups containing 1 to 2 phenyl groups; X ₄ is O, NH or N(R ₆ ), R ₆ is a C ₁ -C ₆ alkyl group; _R5 is H or methyl; f is an integer of 1 to 6. The photocurable packaging ink according to claim 5, characterized in that the photocurable packaging ink contains an acrylate crosslinking agent in which Ar ₄ is selected from unsubstituted or hydroxyl-substituted C ₃ -C ₁₂ alkane groups. The photocurable packaging ink according to claim 5, characterized in that Ar ₄ is selected from:

*The position corresponds to the connection with the X ₄ group in X ₄ OCC(R ₅ )=CH ₂ . The photocurable packaging ink according to claim 5, characterized in that the photocurable packaging ink comprises 35%-65% (weight) of the ether unsaturated resin monomer of Chemical Formula 1, 30%-60% (weight) of an acrylate crosslinking agent of the general formula Ar ₄ [X ₄ OCC(R ₅ )＝CH ₂ ] _f , and 0.1%-10% (weight) of a photoinitiator. The photocurable packaging ink according to claim 1, characterized in that the photocurable packaging ink further comprises one or more of 0.1%-5% (by weight) of a surfactant, 0.1%-5% (by weight) of an adhesion promoter or 0.1%-5% (by weight) of a defoaming agent. A display device comprises at least a substrate and an encapsulation layer, and a light-emitting element located therebetween, characterized in that the photocurable encapsulation ink described in any one of claims 1 to 9 constitutes the encapsulation layer alone or in combination with at least one inorganic barrier layer.