KR20230022968A - Encapsulant for display element and cured product thereof - Google Patents

Abstract

A radically polymerizable monomer mixture containing a silicone-free acrylate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), wherein the radically polymerizable monomer mixture satisfies the following condition 1, Sealant for display elements. Condition 1: 5 g of the radically polymerizable monomer mixture and a stirrer were placed in a 10 mL vial bottle, 0.2 g of TPO powder was added at 25 ° C., and the stirring speed was 1000 rpm. The TPO powder was completely dissolved visually within 30 minutes of stirring time. . Here, as the TPO powder, it was ground with a mortar, and the mesh No. of JIS Z 8801-1 was obtained. Use what was filtered through a mesh of 14 (eye size 1.01 mm).

Description

Encapsulant for display element and cured product thereof

This invention relates to the sealing agent for display elements, and its hardened|cured material.

In the field of a display element, examination for improving the characteristics of a sealing agent is made|formed. Hereinafter, an organic EL display device will be described as an example.

Since an organic EL element consumes little power, it is used for displays, lighting devices, and the like. Since organic EL devices are easily deteriorated by moisture or oxygen in the air, they are used while being sealed with various sealing members, and improvement in durability of various sealing members against moisture and oxygen is desired for practical use.

As such a sealing member, many sealing agents using thermosetting epoxy-based materials have been proposed. However, there is room for improvement in that a heating step is required for curing and there is a possibility that the organic EL element may be damaged by heating.

As an organic EL encapsulant that does not require curing by heating, encapsulants using acrylic materials have also been proposed. For example, in Patent Document 1 (International Publication No. 2019/82996), an acyclic C6 or more alkanediol di(meth)acrylate in an organic electroluminescence display element encapsulant, a specific cyclic monomer, An encapsulant for organic EL display elements containing a photopolymerization initiator has been proposed.

International Publication No. 2019/82996

When the present inventors examined using acrylic resin for the sealing layer of a display device, in the cured film obtained from the sealing agent using an acrylic material, with the passage of time, 2,4,6-trimethylbenzoyldiphenylphos Components in sealants such as pin oxide (TPO) may float on the surface of the cured film, that is, bleed out, and it has been found that the tendency becomes remarkable in a high temperature and high humidity environment. In addition, there is room for improvement in that there is a concern that a large amount of outgas may be generated due to the acrylic material remaining in the manufacturing process of the display element.

This invention provides the sealing agent for display elements which bleed-out to the surface of a resin film is suppressed and is also excellent in low out-gassing property.

ADVANTAGE OF THE INVENTION According to this invention, the sealing agent and hardened|cured material for display elements shown below are provided.

[1] A radically polymerizable monomer mixture containing silicone-free acrylate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), wherein the radically polymerizable monomer mixture is the following condition 1 The encapsulant for display elements which satisfies the.

Condition 1: 5 g of the radically polymerizable monomer mixture and a stirrer were placed in a 10 mL vial bottle, 0.2 g of TPO powder was added at 25 ° C., and the stirring speed was 1000 rpm. The TPO powder was completely dissolved visually within 30 minutes of stirring time. do. Here, the TPO powder was ground in a mortar, and the mesh No. of JIS Z 8801-1 was used. Use what was filtered through a mesh of 14 (eye size 1.01 mm).

[2] The encapsulant for display elements according to [1], wherein the radically polymerizable monomer mixture consists only of a bifunctional (meth)acrylate.

[3] The bifunctional (meth)acrylate is (A) silicone-free and cyclic skeleton-free bifunctional (meth)acrylate, the sealing agent for display elements described in [2].

[4] The said bifunctional (meth)acrylate is sealing agent for display elements as described in [3] which further contains (B) silicone-free alicyclic bifunctional (meth)acrylate.

[5] The sealing agent for display elements according to any one of [2] to [4], wherein the bifunctional (meth)acrylate contains a bifunctional acrylate and a bifunctional methacrylate.

[6] The sealing agent for display elements according to [4], wherein the content of the component (A) is 30 parts by mass or more and 70 parts by mass or less with respect to a total of 100 parts by mass of the components (A) and (B).

[7] The sealing agent for display elements according to any one of [1] to [6], which is for sealing organic EL display elements.

[8] A cured product formed by curing the encapsulant for display elements according to any one of [1] to [7].

On the other hand, any combination of each of these configurations and conversion of the expression of the present invention among methods, devices, etc. are also effective as aspects of the present invention.

For example, according to the present invention, a substrate, a display element disposed on the substrate, and a sealing layer covering the display element are included, and the sealing layer is the ultraviolet curable resin composition in the present invention. A display device composed of a cured product can also be provided.

ADVANTAGE OF THE INVENTION According to this invention, the bleed-out to the surface of a resin film is suppressed, and the sealing agent for display elements excellent also in low out-gassing property can be provided.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described using drawing. In addition, in all drawings, common reference numerals are attached to the same components, and explanations are omitted appropriately. In addition, in this embodiment, about each component, each 1 type may be used, respectively, and you may use it in combination of 2 or more types. In addition, "-" which represents a numerical range represents above and below, and includes both an upper limit value and a lower limit value.

(Encapsulant for display element)

In the present embodiment, the encapsulant for display elements (hereinafter, simply referred to as "encapsulant" as appropriate) is a composition used for encapsulation of a display element, and a radically polymerizable monomer mixture containing a silicon-free acrylate, and Contains 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO). And, the radically polymerizable monomer mixture satisfies Condition 1 below.

Condition 1: 5 g of the radically polymerizable monomer mixture and a stirrer were placed in a 10 mL vial bottle, 0.2 g of TPO powder was added at 25 ° C., and the stirring speed was 1000 rpm. The TPO powder was completely dissolved visually within 30 minutes of stirring time. . Here, as the TPO powder, it was ground with a mortar, and the mesh No. of JIS Z 8801-1 was obtained. Use what was filtered through a mesh of 14 (eye size 1.01 mm).

In condition 1, more specifically, the pre-determined vial bottle is Mighty Vial No. 5 (manufactured by Maruem Corporation, code number 0102-18), and the stirrer is a triangle rotor 20 × 8 mm (manufactured by As One Corporation, model number 011.420).

In this embodiment, while the radically polymerizable monomer mixture in the sealing agent contains silicone-free acrylate and TPO, the radically polymerizable monomer mixture satisfies condition 1 described above regarding the solubility of TPO. For this reason, while bleed-out to the surface of the resin film of sealing agent, for example, a coating film, is suppressed suitably, the resin film excellent also in low out-gassing property can be obtained. Moreover, according to this embodiment, it also becomes possible to suppress bleed-out of TPO to the surface of the resin film of sealing agent, for example.

When the radically polymerizable monomer mixture satisfies condition 1 described above for the solubility of TPO, the reason why a resin film excellent in suppression of bleed-out and low outgassing property is obtained is not necessarily clear, but TPO and resin (radical polymerizable monomer mixture) When the polarity of is close, TPO can stably exist inside the resin, so bleed-out is difficult to occur, and since TPO is non-localized throughout the resin, the reaction proceeds uniformly, leaving unreacted components I think it's difficult.

That is, the present inventors newly paid attention to the TPO solubility of the radically polymerizable monomer mixture as a design guideline for suppressing bleed-out and out-gas. When the TPO dissolution time is short, it means that the compatibility between TPO and the radically polymerizable monomer mixture is excellent, and when it is long, the polarity of TPO and the resin becomes far away, so it cannot stably exist inside the resin, so bleed-out occurs. Since it is easy and it is difficult for TPO to be delocalized throughout the resin, the reaction proceeds non-uniformly, meaning that the progress of curing becomes sparse, so the present inventors use radical polymerization as an indicator of the ease of generating bleed-out and out-gas It was considered that the TPO solubility of the monomer mixture was effective.

Then, as a result of further intensive studies by the present inventors, the radically polymerizable monomer mixture has a configuration containing a silicone-free acrylate and, with respect to TPO solubility, by setting the configuration to satisfy the above condition 1, bleed It was discovered that out and out gas could be effectively suppressed, and the present invention was completed.

In condition 1, the time from the start of stirring until TPO is completely dissolved is within 30 minutes, preferably within 25 minutes, more preferably within 20 minutes, from the viewpoint of improving the effect of suppressing bleed-out and out-gas. within, more preferably within 18 minutes.

Moreover, in condition 1, the time from the start of stirring until TPO is completely dissolved is 0 minutes or more, for example, it may be 1 minute or more.

Hereinafter, components included in the encapsulant will be described in more detail.

(Radically polymerizable monomer mixture)

A radically polymerizable monomer mixture is a mixture containing two or more types of radically polymerizable monomers specifically,. The radically polymerizable monomer mixture contains a silicone-free acrylate as a radically polymerizable monomer.

Specific examples of the silicone-free acrylate include silicone-free monofunctional monoacrylate, silicone-free difunctional acrylate, and trifunctional or higher-functional silicone-free acrylate. From the viewpoint of improving the effect of suppressing bleed-out and outgas, the silicon-free acrylate preferably includes a silicon-free bifunctional acrylate, and more preferably is a silicon-free bifunctional acrylate.

From the viewpoint of improving the effect of suppressing bleed-out and outgas, the radically polymerizable monomer preferably does not contain silicon-containing acrylate, more preferably does not contain silicon-containing (meth)acrylate.

Here, in this specification, silicon-free acrylate refers to an acrylate that does not contain Si in its molecular structure, and silicon-containing acrylate refers to an acrylate that contains Si in its molecular structure.

In addition, (meth)acrylate means at least one of acrylate and methacrylate. A (meth)acryloyl group means at least one of an acryloyl group and a methacryloyl group. A (meth)acryl means at least one of an acryl or methacryl.

From the viewpoint of obtaining uniform curability, the radically polymerizable monomer mixture preferably contains a bifunctional (meth)acrylate, and more preferably consists only of a bifunctional (meth)acrylate.

From the viewpoint of improving the uniformity of the curing rate, the bifunctional (meth)acrylate preferably includes a bifunctional acrylate and a bifunctional methacrylate.

Further, from the viewpoint of improving the compatibility with TPO, the bifunctional (meth)acrylate preferably includes (A) a silicone-free and cyclic skeleton-free bifunctional (meth)acrylate, and more preferably includes (A) silicone-free and cyclic backbone-free difunctional (meth)acrylates, and (B) silicone-free alicyclic difunctional (meth)acrylates.

(Component (A))

Component (A) is a difunctional (meth)acrylate containing no silicone and no cyclic skeleton. Component (A) is a (meth)acrylate having two (meth)acrylic groups while not including Si in its molecular structure and not including an alicyclic structure or an aromatic ring cyclic skeleton.

Component (A) preferably contains a divalent chain hydrocarbon group, which may have a branched chain, and more preferably contains a straight chain hydrocarbon group, from the viewpoint of making inkjet coatability more preferable. The number of carbon atoms in the divalent chain hydrocarbon group is, for example, 1 or more, preferably 2 or more, more preferably 4 or more, from the viewpoint of easy availability of the monomer. From the viewpoint of improving heat resistance, the number of carbon atoms in the divalent chain hydrocarbon group is preferably 20 or less, and more preferably 14 or less.

Specific examples of the component (A) include di(meth)acrylates of alkane diols and di(meth)acrylates having a branched hydrocarbon structure.

As component (A), more specifically, 1,6-hexanediol diacrylate (eg A-HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,9-nonanediol diacrylate (eg A-NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.; light acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd.), 1,10-decanediol diacrylate (eg A-DOD -N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), ethylene glycol diacrylate (eg SR206NS, manufactured by Arkema), triethylene glycol diacrylate (eg SR272, manufactured by Arkema), polyethylene glycol acrylates such as col diacrylate (eg A-400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) and neopentyl glycol diacrylate (eg, Light Acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd.); And, 1,3-butanediol dimethacrylate (eg BG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,4-butanediol dimethacrylate (eg BD, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) ), 1,6-hexanediol dimethacrylate (for example, HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,9-nonanediol dimethacrylate (for example, NOD-N, new Nakamura Chemical Industry Co., Ltd. light acrylate 1,9-ND-M, Kyoeisha Chemical Industry Co., Ltd.), 1,10-decanediol dimethacrylate (eg DOD-N, Shin Nakamura Chemical Industry Co., Ltd.), Methacrylates such as 1,12-dodecanediol dimethacrylate (eg SR262, manufactured by Sartomer Co., Ltd.) and neopentyl glycol dimethacrylate (eg NPG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) can be heard

Component (A) is selected from the group consisting of 1,9-nonanediol di(meth)acrylate from the viewpoint of improving plasma resistance, improving application stability in the inkjet method, and improving the balance of the effects of low dielectric constant. at least one (meth)acrylate.

The content of the component (A) in the encapsulant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, with respect to 100 parts by mass of the radically polymerizable monomer, from the viewpoint of making inkjet applicability more preferable, It is more preferably 15 parts by mass or more, and even more preferably 20 parts by mass or more.

Further, from the viewpoint of improving the hardness of the cured product, the content of component (A) in the encapsulant is preferably 99.5 parts by mass or less, more preferably 95 parts by mass or less, with respect to 100 parts by mass of the radically polymerizable monomer. Preferably it is 85 parts by mass or less.

(Component (B))

Component (B) is a silicone-free alicyclic difunctional (meth)acrylate.

Component (B) is, specifically, a bifunctional (meth)acrylate having an alicyclic hydrocarbon structure in its molecular structure. The number of carbon atoms in the alicyclic hydrocarbon structure is preferably 4 or more, more preferably 5 or more, still more preferably 6 or more, and more preferably 14 or less, more preferably from the viewpoint of improving heat resistance. 12 or less, more preferably 10 or less.

The alicyclic hydrocarbon structure may be either a saturated hydrocarbon structure or an unsaturated hydrocarbon structure. From the viewpoint of improving heat resistance, the alicyclic hydrocarbon structure is preferably a saturated hydrocarbon structure.

Further, the alicyclic hydrocarbon structure may be a monocyclic hydrocarbon structure or a polycyclic hydrocarbon structure of a condensed cyclic hydrocarbon structure or a bridged cyclic hydrocarbon group structure. The alicyclic bifunctional (meth)acrylate may contain a group containing these alicyclic hydrocarbon structures in its molecular structure, and preferably contains a divalent group containing an alicyclic hydrocarbon structure.

Specific examples of the monocyclic hydrocarbon group include groups having a cycloalkane structure such as a cyclohexylene group and a cyclohexyl group; and groups having cycloalkene skeletons such as cyclodecatrienediyl group and cyclodecatriene group.

Specific examples of the polycyclic hydrocarbon group include groups having a dicyclopentadiene skeleton such as a tricyclodecanediyl group, a dicyclopentanyl group, and a dicyclopentenyl group; groups having norbornene skeletons such as norborneindiyl group, isoborneindiyl group, norbornyl group, and isobornyl group; and groups having adamantane skeletons such as adamantanediyl group and adamantyl group.

From the viewpoint of improving yellowing resistance, the cyclic hydrocarbon group in component (B) is preferably a group having a dicyclopentadiene skeleton.

In addition, component (B) is tricyclodecane dimethanol di(meth)acrylate (for example, light acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.; DCP, Shin Nakamura, from a viewpoint of improving the hardness of hardened|cured material) chemical industry), more preferably tricyclodecane dimethanol di(meth)acrylate.

The content of component (B) in the encapsulant is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and still more preferably 100 parts by mass of the radically polymerizable monomer, from the viewpoint of improving the hardness of the cured product. is 15 parts by mass or more, more preferably 20 parts by mass or more, still more preferably 25 parts by mass or more.

In addition, from the viewpoint of improving the ejection property of inkjet, the content of component (B) in the sealant is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, with respect to 100 parts by mass of the radically polymerizable monomer, It is more preferably 60 parts by mass or less, and even more preferably 55 parts by mass or less.

The content of component (A) relative to 100 parts by mass of the total of components (A) and (B) is, for example, 3 parts by mass or more, preferably 30 parts by mass or more, from the viewpoint of improving inkjet coatability, More preferably, it is 35 mass parts or more, More preferably, it is 40 mass parts or more.

From the viewpoint of improving the hardness of the cured product, the content of component (A) relative to 100 parts by mass of the total of components (A) and (B) may be, for example, 98 parts by mass or less, preferably 70 parts by mass or less. , more preferably 60 parts by mass or less, still more preferably 55 parts by mass or less.

The content of the bifunctional acrylate relative to 100 parts by mass of the total of the bifunctional acrylate and the bifunctional methacrylate is preferably 5 parts by mass or more, and more preferably 10 parts by mass or more, from the viewpoint of improving the reaction rate. , It is more preferably 15 parts by mass or more, still more preferably 25 parts by mass or more, and even more preferably 35 parts by mass or more.

Further, from the viewpoint of elongation of the resin chain length, the content of the bifunctional acrylate with respect to the total of 100 parts by mass of the bifunctional acrylate and the bifunctional methacrylate may be, for example, 98 parts by mass or less, preferably 90 It is less than 60 parts by mass, more preferably less than 80 parts by mass, still more preferably less than 70 parts by mass, still more preferably less than 60 parts by mass, still more preferably less than 55 parts by mass.

The radically polymerizable monomer may also contain (meth)acrylates other than silicone-free linear difunctional (meth)acrylates.

Specific examples of (meth)acrylates other than silicone-free linear difunctional (meth)acrylates include silicone-free monofunctional (meth)acrylates and silicone-free trifunctional or higher polyfunctional (meth)acrylates. can

Specific examples of the silicone-free monofunctional (meth)acrylates include mono(meth)acrylates having a hydrocarbon group having a linear or branched chain in the molecular structure and mono(meth)acrylates having an aromatic hydrocarbon group in the molecular structure. there is. Examples of the former include lauryl methacrylate and isostearyl acrylate, and examples of the latter include 3-phenoxybenzyl acrylate.

From the viewpoint of further enhancing the effect of suppressing bleed-out and out-gas, the sealant preferably does not contain (meth)acrylates other than silicone-free linear bifunctional (meth)acrylates. That is, the content of (meth)acrylates other than the silicone-free linear bifunctional (meth)acrylate in the sealant is preferably 0 parts by mass with respect to 100 parts by mass of the radically polymerizable monomer.

From the same point of view, when the encapsulant contains a (meth)acrylate other than silicone-free linear bifunctional (meth)acrylate, the content is greater than 0 parts by mass with respect to 100 parts by mass of the radically polymerizable monomer, and For example, it is 1 part by mass or less, preferably 0.5 part by mass or less, more preferably 0.1 part by mass or less, still more preferably 0.01 part by mass or less.

The content of the radical polymerizable monomer in the encapsulant is preferably 70% by mass or more, more preferably 80% by mass or more, and more preferably 80% by mass or more, with respect to the total composition of the encapsulant, from the viewpoint of improving the strength of the cured product. 85% by mass or more, more preferably 90% by mass or more, still more preferably 93% by mass or more.

From the viewpoint of improving the weather resistance of the sealing material, the content of the polymerizable compound in the sealing agent is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, and still more preferably 99.5% by mass or less, relative to the total composition of the sealing agent. It is preferably 99% by mass or less, and even more preferably 98% by mass or less.

(TPO)

The encapsulant includes 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO). Specifically, TPO functions as a photopolymerization initiator, which is a compound that generates radicals or acids when irradiated with ultraviolet rays or visible rays.

The content of TPO in the encapsulant is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, with respect to the total composition of the encapsulant, from the viewpoint of improving curability. More preferably, it is 2 mass % or more.

From the viewpoint of suppressing the coloring of the sealing agent, the content of TPO in the sealing agent is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 8% by mass or less, relative to the total composition of the sealing agent. It is 6 mass % or less, More preferably, it is 5 mass % or less.

(other ingredients)

In this embodiment, the sealing agent may be comprised of the radically polymerizable monomer mixture and TPO, and may contain components other than these. As specific examples of other components, 1 or 2 selected from the group consisting of tackifiers, fillers, curing accelerators, plasticizers, surfactants, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, leveling agents such as fluorine-based leveling agents, and ultraviolet absorbers The above additives are mentioned.

For example, when a sealing agent contains a leveling agent, its content can be about 0.01-1 mass %, Preferably it is about 0.1-0.5 mass % with respect to the whole composition of sealing agent.

The properties of the sealing agent are not limited, and from the viewpoint of improving the flexibility and plasma resistance of the sealing material, and from the viewpoint of being suitable for forming a cured material by a coating method such as an inkjet method, the sealing agent is preferably liquid. .

Further, in the embodiment, from the viewpoint of stably forming a sealing material such as a resin film, the sealing agent is preferably a sealing agent used for application, more preferably a sealing agent used for application by an inkjet method. am.

Next, the manufacturing method of sealing agent is demonstrated.

The manufacturing method of the sealant is not limited, and includes, for example, mixing a polymerizable compound, a curing agent, and other components as appropriate, for example, various additives added as needed. As a method of mixing each component, for example, a planetary stirring device, a homodisper, a universal mixer, a Banbury mixer, a kneader, a 2-roll, 3-roll, extruder, etc., alone or in combination with known various kneaders, or a method of uniformly kneading under conditions such as under normal pressure, under reduced pressure, under pressure, under heating, under conditions such as under pressure or under an inert gas stream.

Here, the sealing agent which satisfies condition 1 about TPO solubility can be obtained by adjusting mixing conditions of a component, for example while adjusting the component and content contained in sealing agent. More specifically, while selecting a plurality of bifunctional (meth)acrylates as a radically polymerizable monomer mixture and using them in combination, mixing each monomer while controlling the oxygen concentration and temperature in the atmosphere in the preparation of the sealant By obtaining a radically polymerizable monomer mixture by doing so, it is possible to more stably obtain a sealant that satisfies condition 1 with respect to TPO solubility.

Moreover, a resin film can also be formed using the obtained sealing agent. For example, an encapsulant may be applied onto a substrate and cured. For application, known methods such as inkjet method, screen printing, and dispenser application can be used.

Moreover, in this embodiment, the hardened|cured material is made by hardening the sealing agent in this embodiment.

In this embodiment, since the encapsulant contains TPO and a radically polymerizable monomer mixture containing silicone-free acrylate, and the radical polymerizable monomer mixture satisfies condition 1 with respect to TPO solubility, such encapsulant By using it, it is possible to obtain a resin film excellent in suppressing effect of bleed-out to the surface of the resin film and low out-gassing property. According to this embodiment, it also becomes possible to suppress bleed-out under high temperature, high humidity, for example. Moreover, according to this embodiment, it also becomes possible to obtain the display device excellent in manufacturing stability, for example by using the resin film obtained by the sealing agent as a sealing material.

Taking an organic EL display device as an example as a display device, the organic EL display device has a layer composed of a cured product of a sealing agent, for example, a sealing layer.

In addition, the sealing agent in this embodiment is preferably for sealing an organic EL display element.

Moreover, the sealing agent obtained in this embodiment is used suitably for sealing of a display element, for example, preferably an organic electroluminescent display element, for example. According to the present embodiment, it is possible to stably apply the resin layer by the inkjet method during formation, and it is possible to effectively suppress the occurrence of dark spots during element light emission, and it is also possible to improve the manufacturing stability of the display device. .

Example

Hereinafter, the present invention will be described by Examples and Comparative Examples, but the present invention is not limited thereto.

First, the materials used in the following examples are shown.

(radically polymerizable monomer)

(A) Bifunctional (meth)acrylates free of silicone and free of cyclic backbones

1,9-nonanediol diacrylate: light acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd., linear bifunctional acrylate, silicone-free acrylate

1,9-nonanediol dimethacrylate: NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., linear bifunctional methacrylate

1,12-dodecanediol dimethacrylate: SR262, manufactured by Sartomer, linear bifunctional methacrylate

Neopentyl glycol diacrylate: light acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd., bifunctional acrylate, silicone-free acrylate

(B) silicone-free alicyclic difunctional (meth)acrylate

Dimethylol-tricyclodecane dimethacrylate: DCP, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., bifunctional methacrylate

Dimethylol-tricyclodecane diacrylate: light acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd., bifunctional acrylate, silicone-free acrylate

(other (meth)acrylates)

Isostearyl acrylate: S1800, manufactured by Shin-Nakamura Chemical Industry Co., Ltd., monofunctional acrylate, silicone-free acrylate

Silicone-containing bifunctional methacrylate: X-22-164AS, manufactured by Shin-Etsu Chemical Co., Ltd.

(Polymerization initiator)

(C) 2,4,6-trimethylbenzoyl-diphenylphosphine oxide: Omnirad TPO H, manufactured by GM Resins

(leveling agent)

Fluorine-based leveling agent: F552, manufactured by DIC

(Examples 1 to 7, Comparative Examples 1 to 3)

Each component of Table 1 was mix|blended, and the liquid curable composition was obtained as the sealing agent of each case.

In each Example, first, among the components listed in Table 1, radically polymerizable monomers were mixed in a brown vial bottle at room temperature (25°C) under an atmospheric environment with an oxygen concentration of 20.0 to 21.0% to obtain radically polymerizable monomers. A mixture was obtained. In addition, from the viewpoint of reducing the possibility of runaway, methacrylate was put first, and acrylate was put later. The TPO solubility of the resulting radically polymerizable monomer mixture was evaluated by the method described later.

Next, the radically polymerizable monomer mixture and the other components listed in Table 1 were mixed in an atmospheric environment with an oxygen concentration of 20.0 to 21.0% at 20 to 60°C in a brown vial to obtain the composition of each case.

About the hardened|cured material of the composition obtained in each case, the presence or absence of bleed-out and out-gas under high-temperature, high-humidity conditions were measured by the following method. A measurement result is combined with Table 1 and shown.

(TPO solubility)

The TPO solubility of the radically polymerizable monomer mixture (hereinafter also referred to as "monomer liquid") in each case was evaluated in the following procedure.

1. 5 g of the monomer solution was placed in a 10 mL vial (brown, Mighty Vial No. 5 (manufactured by Maruem Co., Ltd., code number 0102-18)).

2. Grind the TPO uniformly and finely with a mortar, JIS Z 8801-1 mesh No. It was filtered through a mesh of 14 (eye size 1.01 mm).

3. TPO 0.2g of the fraction under the mesh in said 2. was injected|thrown-in at 25 degreeC.

4. It stirred at 1000 rpm with the stirrer (Triangle rotor 20x8mm (made by As One company, model number 011.420)).

5. The time from the start of stirring until TPO was completely dissolved was visually confirmed. For those in which TPO was not completely dissolved after 30 minutes had elapsed, it was described as "insoluble even after 30 minutes".

(High temperature and high humidity test)

The presence or absence of bleed-out under high-temperature, high-humidity conditions was evaluated in the following procedure.

1. The compounding solution was applied to a 50 mm x 50 mm alkali-free glass using a spin coater to have an average film thickness of 8 µm.

2. It was sealed in a nitrogen purge box and nitrogen was flowed for 3 minutes.

3. 1500mW 5600mJ (UVA2) was irradiated and cured.

4. It was put into a constant temperature and humidity chamber at 85°C and 85% RH, and was taken out after 500 hours.

5. When no bleed-out occurred visually, it was evaluated as "OK", and when bleed-out had occurred, it was evaluated as "x".

(outgas evaluation)

The amount of outgas generated was evaluated in the following procedure.

1. The sealing agent obtained in each case was applied to a 50 mm × 50 mm alkali-free glass using a spin coater so as to have an average film thickness of 8 μm.

2. The coating film obtained in 1. above was sealed in a nitrogen purge box, and nitrogen was flowed for 3 minutes.

3. 1500mW 5600mJ (UVA2) was irradiated and cured.

4. The test piece prepared in 3. above was cut into 10 mm x 50 mm, heated at 110°C for 30 minutes by the head space method, and the amount of outgas generated was collected by gas chromatography.

5. The amount of outgas [ppm] collected in 4. above was quantified based on toluene.

From Table 1, in each Example, bleed-out to the surface of the coating film under high temperature, high humidity was suppressed, and the low out-gassing property was also excellent.

This application claims priority based on Japanese Patent Application No. 2020-157661 filed on September 18, 2020, the entire disclosure of which is incorporated herein.

Claims (8)

A radically polymerizable monomer mixture containing a silicone-free acrylate and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), wherein the radically polymerizable monomer mixture satisfies condition 1 below. , sealing agent for display elements.
Condition 1: 5 g of the radically polymerizable monomer mixture and a stirrer were placed in a 10 mL vial bottle, 0.2 g of TPO powder was added at 25 ° C, and the stirring speed was 1000 rpm. The TPO powder was completely dissolved visually within 30 minutes of stirring time. do. Here, the TPO powder was ground in a mortar, and the mesh No. of JIS Z 8801-1 was used. Use what was filtered through a mesh of 14 (eye size 1.01 mm). According to claim 1,
The sealing agent for display elements in which the said radically polymerizable monomer mixture consists only of bifunctional (meth)acrylate. According to claim 2,
The said bifunctional (meth)acrylate is the sealing agent for display elements containing (A) silicon-free and cyclic skeleton non-containing bifunctional (meth)acrylate. According to claim 3,
The bifunctional (meth) acrylate, (B) silicon-free alicyclic bifunctional (meth) acrylate further comprises, the encapsulant for the display element. According to any one of claims 2 to 4,
The sealing agent for display elements in which the said bifunctional (meth)acrylate contains a bifunctional acrylate and a bifunctional methacrylate. According to claim 4,
The sealing agent for display elements whose content of the said component (A) is 30 mass parts or more and 70 mass parts or less with respect to 100 mass parts of the said components (A) and (B) in total. According to any one of claims 1 to 6,
Sealing agent for display elements, which is for sealing of organic EL display elements. A cured product formed by curing the encapsulant for display elements according to any one of claims 1 to 7.