TWI797344B - Sealant for display element and hardened product thereof - Google Patents

Abstract

The sealant for display elements of the present invention contains: (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, (C) an aliphatic epoxy compound (wherein, with the The alicyclic epoxy compound is different) and (D) cationic polymerization initiator, the (A) alicyclic epoxy compound, the (B) oxetane compound, and the (C) fatty The weight-average molecular weights of the epoxy compounds are 180 or more, and the oxygen atom contents represented by the formula (1) are 15% or more. Oxygen atom content rate (%) = total mass of oxygen atoms in 1 molecule / weight average molecular weight × 100... (1)

Description

Sealant for display element and hardened product thereof

The present invention relates to a sealant for display elements and its hardened product.

In recent years, the development of optical semiconductor devices using display elements such as organic electroluminescent elements (hereinafter referred to as organic EL (electroluminescence) elements) has progressed. Display elements such as organic EL elements are easily degraded by moisture or oxygen in the air. Therefore, display elements such as organic EL elements are usually sealed with a sealant (surface seal) and used.

The surface sealing of the organic EL element is performed, for example, by applying a sealant containing a curable resin composition on the organic EL element disposed on the substrate, and then curing the sealant. Conventionally, the coating of the sealant has been performed using a screen printing method. On the other hand, flattening and thinning of the sealing layer are required along with the flexibility of the display device. Along with this, from the viewpoint of being able to uniformly form a high-flatness, thin-film sealing layer at high speed, application of a sealing agent by an inkjet method has been studied.

The sealant used for coating by the inkjet method is required to have a low viscosity in order to be ejected stably from the nozzles of the head. In addition, it is required to suppress swelling of an adhesive or a rubber material used in a head portion of an inkjet device and reduce damage to the device.

As a sealant used in coating by such an inkjet method, a sealant for electronic devices containing a specific silicone epoxy compound as a curable resin and a polymerization initiator has been proposed (for example, Patent Document 1). The sealant does not excessively increase the viscosity by containing the silicone epoxy compound, suppresses swelling of the adhesive or rubber material of the head portion of the inkjet device, and reduces damage to the device.

In addition, as a surface sealing agent for an organic EL element, a resin composition for organic EL surface sealing containing a benzyl cobaltium salt and an epoxy resin or an oxetane resin having an aromatic group has been proposed (for example, Patent Document 2 ). [Prior art literature] [Patent Document]

[Patent Document 1] International Publication No. 2016/167347 [Patent Document 2] Japanese Patent Laid-Open No. 2016-108512

[Problem to be Solved by the Invention] However, the sealant containing a silicone epoxy compound as disclosed in Patent Document 1 has a problem of low curing speed (low curability). After the sealant with low curability is applied to the object to be coated, it is easy to be repelled on the object to be coated (display element) until it hardens, and cannot be sufficiently leveled to form a uniform sealant. Sealing layer. Therefore, it is required to reduce the damage to the device without impairing the hardenability.

In addition, the sealant used for coating by the inkjet method is also required to have a low viscosity. However, the sealant disclosed in Patent Document 2 is not sufficiently curable, and its viscosity is not sufficiently low.

The present invention is made in view of the above circumstances, and an object of the present invention is to provide a sealant for a display element having a low viscosity and a low Volatility and high curability, and less damage to inkjet devices. [Means to solve the problem]

[1] A sealant for display elements, comprising: (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, (C) an aliphatic epoxy compound (wherein, different from the alicyclic epoxy compound) and (D) a cationic polymerization initiator, the (A) alicyclic epoxy compound, the (B) oxetane compound, and the (C ) the weight average molecular weight of the aliphatic epoxy compound is 180 or more, and the oxygen atom content represented by the following formula (1) is 15% or more, Oxygen atom content rate (%)=total mass of oxygen atoms in 1 molecule/weight average molecular weight×100...(1). [2] The sealing compound for display elements according to [1], wherein the content of the (C) aliphatic epoxy compound is larger than the content of the (A) alicyclic epoxy compound. [3] The sealing agent for a display element according to [1] or [2], wherein the content of the (B) oxetane compound is larger than the content of the (C) aliphatic epoxy compound. [4] The sealant for a display element according to any one of [1] to [3], wherein the (A) alicyclic epoxy compound, the (B) oxetane compound, and The (C) aliphatic epoxy compounds are respectively polyfunctional compounds. [5] The sealant for a display element according to any one of [1] to [4], wherein the (A) alicyclic epoxy compound, the (B) oxetane compound, and One or more of the (C) aliphatic epoxy compounds have a carbonyloxy group. [6] The sealant for a display element according to any one of [1] to [5], wherein the viscosity measured with an E-type viscometer at 25° C. and 20 rpm is 50 mPa·s or less. [7] The sealing agent for a display element according to any one of [1] to [6], which is used for coating by an inkjet method. [8] The sealing compound for a display element according to any one of [1] to [7], wherein an organic EL element as the display element is sealed in a planar shape. [9] A cured product of the sealant for a display element according to any one of [1] to [8]. [Effect of the invention]

According to the present invention, there can be provided a sealant for a display element having low viscosity, low volatility, and good curability suitable for coating by an inkjet method, and a cured product thereof, and a cured product thereof. There is less damage to the inkjet device.

The inventors of the present invention conducted diligent research and found that by combining (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, and (C) an alicyclic Oxygen compounds, and by setting the oxygen atom content and weight average molecular weight of each component to a certain level or more, a sealant having low viscosity, low volatility, and high curability and reducing damage to devices can be obtained.

The reason for this is not clear, but it is presumed as follows. First, by combining components (A) to (C), both low viscosity and high curability can be achieved at a high level. In addition, many adhesives and rubber materials used in the head portion of the inkjet device include low-polarity materials such as ethylene-propylene-diene monomer (EPDM) rubber, for example. On the other hand, by setting the oxygen atom content of the (A) component to (C) component at a certain level or higher and increasing the polarity, it is difficult for these components to mix with a low-polarity material used in the head part of the inkjet device. Affinity, and difficult to swell, thereby suppressing the deterioration of these materials. Furthermore, it becomes hard to volatilize by raising moderately the weight average molecular weight of (A) component - (C)component.

Thereby, the sealing agent of this invention can be applied easily by the inkjet method. Thereby, a highly flat and thin hardened material layer can be formed uniformly at high speed. The present invention is based on these findings.

1. Sealant for display elements The sealant for display elements of the present invention contains: (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, (C) an aliphatic epoxy compound, and (D) Cationic polymerization initiator.

＜(A) Alicyclic epoxy compound having cycloolefin oxide structure＞ (A) The alicyclic epoxy compound which has a cycloolefin oxide structure can have the function of improving the curability of the sealing compound for display elements. (A) The alicyclic epoxy compound having a cycloolefin oxide structure is a compound having a cycloolefin oxide structure, and means that the weight average molecular weight is 180 or more and the oxygen atom content represented by the following formula (1) is Compounds above 15%. Oxygen atom content rate (%) = total mass of oxygen atoms in 1 molecule / weight average molecular weight × 100... (1)

If the weight average molecular weight of the alicyclic epoxy compound (A) which has a cycloolefin oxide structure is 180 or more, the volatility of this compound can be reduced. Therefore, it is possible to reduce deterioration of the work environment and damage to the object to be coated (display element) when applying the sealant by the inkjet method. From these viewpoints, the weight average molecular weight of the (A) alicyclic epoxy compound having a cycloolefin oxide structure is preferably 190 or more, more preferably 200 or more. The upper limit of the weight average molecular weight is not particularly limited as long as it does not impair the dischargeability of the sealant when it is applied by an inkjet method, and is more preferably 400 or less, for example.

The weight average molecular weight can be measured in terms of polystyrene using gel permeation chromatography (GPC). As the column, GPC KF-801, a column for low molecular weight manufactured by Shodex, is preferably used. In addition, it can also be calculated from the structural formula of the compound.

(A) If the oxygen atom content of the alicyclic epoxy compound having a cycloolefin oxide structure is 15% or more, the polarity of the compound can be increased, so it can be difficult to mix with the Adhesives or rubber materials with low polarity (eg, ethylene propylene diene rubber, etc.) have affinity and are difficult to swell. Thereby, deterioration of the adhesive or rubber material (damage to the device) can be reduced. From this point of view, the oxygen atom content is preferably 20% or more. The upper limit of the oxygen atom content may be such that the dielectric constant of the obtained sealing layer does not increase too much, for example, it is preferably 30% or less.

(A) The total mass of the oxygen atoms in one molecule of the alicyclic epoxy compound having a cycloolefin oxide structure can be determined by gas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance ( The structure of the alicyclic epoxy compound is determined by the Nuclear Magnetic Resonance (NMR) method, etc., and the number of oxygen atoms in one molecule of the compound is determined, and multiplied by the atomic weight of the oxygen atom to calculate. Furthermore, (A) the oxygen atom content of the alicyclic epoxy compound having a cycloolefin oxide structure can be applied to the formula (1 ) to calculate.

(A) The oxygen atom content of an alicyclic epoxy compound having a cycloolefin oxide structure can be determined by, for example, the number of cycloolefin oxide structures in one molecule, or a linking group having an oxygen atom (for example, -CO- (carbonyl group), -O-CO-O-(carbonate group), -COO-(carbonyloxy or ester group), -O-(ether group), -CONH-(amide group), etc.) Adjustment. That is, in order to increase the oxygen atom content, it is preferable to set the number of cycloolefin oxide structures in 1 molecule to 2 or more, or to introduce a linking group having an oxygen atom.

The so-called (A) cycloalkene oxide structure in the alicyclic epoxy compound having a cycloalkene oxide structure refers to a structure obtained by epoxidizing a cycloalkene with an oxidizing agent such as a peroxide. An epoxy group consisting of two adjacent carbon atoms and an oxygen atom in an aliphatic ring. Examples of cycloalkene oxides include cyclohexene oxide, or cyclopentene oxide, preferably cyclohexene oxide.

(A) The number of cycloolefin oxide structures in one molecule of the alicyclic epoxy compound having a cycloolefin oxide structure may be one (monofunctional) or two or more (polyfunctional). Among them, from the viewpoint of being easy to increase the oxygen atom content and being excellent in transparency, heat resistance, and light resistance, (A) cycloolefin oxidation in one molecule of an alicyclic epoxy compound having a cycloolefin oxide structure The number of object structures is preferably two or more (multifunctional).

That is, the (A) alicyclic epoxy compound having a cycloolefin oxide structure is preferably, for example, a compound represented by the following formula (A-1).

…式（A-1）[chemical 1]

...Formula (A-1)

X in formula (A-1) is a single bond or a linking group. However, X is selected so that the weight average molecular weight and oxygen atom content rate of the compound represented by formula (A-1) satisfy the said range. The linking group can be divalent hydrocarbon group, carbonyl group, ether group (ether bond), thioether group (thioether bond), ester group (ester bond), carbonate group (carbonate bond), amide group (amide bond) , or a base formed by connecting a plurality of these.

The divalent hydrocarbon group may be an alkylene group having 1 to 18 carbon atoms, or a divalent alicyclic hydrocarbon group. Examples of the alkylene group having 1 to 18 carbon atoms include methylene, methylmethylene, dimethylmethylene, ethylylene, propylylene and trimethylene. Examples of divalent alicyclic hydrocarbon groups include: 1,2-cyclopentyl, 1,3-cyclopentyl, cyclopentylene, 1,2-cyclohexyl, 1,3-cyclohexyl, 1 , 4-cyclohexylene, cyclohexylene and other divalent cycloalkylene groups (including cycloalkylene groups).

Among them, X is preferably a single bond or a linking group having an oxygen atom. The linking group with an oxygen atom is more preferably -CO- (carbonyl), -O-CO-O- (carbonate group), -COO- (ester group), -O- (ether group), -CONH- (acyl group) amino group), a group in which a plurality of these groups are connected, or a group in which one or more of these groups are connected to one or more divalent hydrocarbon groups.

Examples of the alicyclic epoxy compound represented by formula (A-1) include the following compounds. Furthermore, in the following formulae, l is an integer of 1 to 10, m is an integer of 1 to 30, and R is an alkylene group with 1 to 8 carbon atoms, preferably methylene, ethylene, or propylene An alkylene group having 1 to 3 carbon atoms such as an isopropyl group and an isopropyl group. n1 and n2 are integers of 1-30, respectively.

[Chem 2]

(A) Commercially available examples of alicyclic epoxy compounds having a cycloolefin oxide structure include Celloxide 2021P, Celloxide 2081, and Celloxide 8000 ( Daicel (manufactured by Daicel), etc.

(A) It is preferable that content of the alicyclic epoxy compound which has a cycloolefin oxide structure is 10 mass % - 70 mass % with respect to the gross mass of a sealant. (A) When the content of the alicyclic epoxy compound having a cycloolefin oxide structure is 10% by mass or more, it is easy to sufficiently improve the curability, and when it is 70% by mass or less, it is difficult to impair the flexibility or adhesion of the cured product. sex. From this point of view, the (A) content of the alicyclic epoxy compound having a cycloolefin oxide structure is more preferably 10% by mass to 50% by mass, more preferably 10% by mass, based on the total mass of the sealant ~30% by mass.

＜(B) Oxetane compound＞ (B) The oxetane compound may have a function of making the sealant low in viscosity and improving hardenability. (B) The oxetane compound is a compound having an oxetanyl group, and refers to a compound having a weight average molecular weight of 180 or more and an oxygen atom content represented by the above formula (1) of 15% or more.

If the weight average molecular weight of the (B) oxetane compound is 180 or more, the volatility of the compound can be reduced in the same manner as above. Therefore, it is possible to reduce deterioration of the work environment and damage to the object to be coated (display element) when applying the sealant by the inkjet method. From the viewpoint of reducing the volatility of the sealant, the weight average molecular weight of the (B) oxetane compound is preferably 190 or more, more preferably 200 or more. The upper limit of the weight average molecular weight should just be the level which does not impair the dischargeability of the sealant when it applies by the inkjet method, For example, it is more preferably 400 or less. The weight average molecular weight can be measured by the same method as mentioned above.

If the oxygen atom content of the (B) oxetane compound is 15% or more, the polarity of the compound can be increased in the same manner as described above, so that the polarity of the compound used in the head part of the inkjet device can be reduced. Deterioration of the adhesive, etc. (damage to the device). From the viewpoint of reducing damage to the device, the oxygen atom content of the (B) oxetane compound is preferably 20% or more. From the viewpoint that the dielectric constant of the sealing layer does not increase too much, the oxygen atom content is preferably, for example, 30% or less. The oxygen atom content can be defined and measured in the same manner as above.

In order to increase the oxygen atom content of the (B) oxetane compound, for example, the number of oxetanyl groups in one molecule of the compound, the group containing an oxygen atom (for example, the formula (B-1 ) The polyoxyalkylene group represented by _R2 , or the oxygen atom contained in _R2 , or the number of oxygen-atom-containing groups such as carbonyl or sulfonyl group is sufficient.

The number of oxetanyl groups in one molecule of such (B) oxetane compound may be one (monofunctional), or two or more (polyfunctional). Among them, two or more are preferable (polyfunctional) from the viewpoints of easily increasing the oxygen atom content and improving curability.

(B) The oxetane compound is preferably a compound represented by the following formula (B-1) or formula (B-2).

…式（B-1）

…式（B-2）[Chem 3]

...Type (B-1)

...Type (B-2)

R ₁ of formula (B-1) and formula (B-2) is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, an aralkyl group, a furyl group or a thienyl group, respectively. R ₂ are respectively divalent organic residues. Among them, R ₁ and R ₂ are selected so that the weight average molecular weight and oxygen atom content of the compounds represented by formula (B-1) and formula (B-2) satisfy the above-mentioned range.

Examples of the alkyl group having 1 to 6 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, and cyclohexyl. Examples of aryl groups include: phenyl, naphthyl, tolyl, xylyl. Examples of aralkyl groups include benzyl, phenethyl.

、

Examples of divalent organic residues include alkylene groups, polyoxyalkylene groups, phenylene groups, xylylene groups, and structures represented by the following formulae. [chemical 4]

,

In the formula, R ₃ is an oxygen atom, a sulfur atom, -CH ₂ -, -NH-, -SO-, -SO ₂ -, -C(CF ₃ ) ₂ - or -C(CH ₃ ) ₂ -.

R ₄ is an alkylene or arylylene group having 1 to 6 carbon atoms. Examples of the alkylene group include an alkylene group having 1 to 15 carbon atoms, such as a methylene group, an ethylidene group, a propylidene group, a butylene group, and a cyclohexylene group. The polyoxyalkylene group is preferably a polyoxyalkylene group having 4 to 30 carbon atoms, preferably 4 to 8, and examples thereof include polyoxyethylene groups and polyoxypropylene groups.

(B) It is preferable that content of an oxetane compound is 20 mass % - 80 mass % with respect to the gross mass of a sealing agent. When the content of the (B) oxetane compound is 20% by mass or more, it is easy to sufficiently reduce the viscosity of the sealant and improve the hardenability, and if it is 80% by mass or less, it is easy to suppress (A) component or (C) Decreased curability due to excessive reduction of components. From such viewpoints, the content of the (B) oxetane compound is more preferably from 25% by mass to 80% by mass, more preferably from 30% by mass to 70% by mass, based on the total mass of the sealant.

＜(C) Aliphatic epoxy compound＞ (C) The aliphatic epoxy compound can easily make the sealant low-viscosity and improve the flexibility or adhesiveness of the cured product. (C) The aliphatic epoxy compound is a glycidyl ether of an aliphatic alcohol (including polyhydric alcohol) not having an aromatic ring, and refers to a weight average molecular weight of 180 or more and an oxygen atom content represented by the above formula (1) For more than 15% of the compound.

If the weight average molecular weight of (C) aliphatic epoxy compound is 180 or more, the volatility of this compound can be reduced similarly to the above. Therefore, it is possible to reduce deterioration of the work environment and damage to the object to be coated (display element) when applying the sealant by the inkjet method. From the viewpoint of further reducing the volatility of the sealant, the weight average molecular weight of the (C) aliphatic epoxy compound is preferably 190 or more, more preferably 200 or more. The upper limit of the weight average molecular weight should just be the level which does not impair the dischargeability of the sealant when it applies by the inkjet method, For example, it is more preferably 400 or less. The weight average molecular weight can be measured by the same method as mentioned above.

If the oxygen atom content of the (C) aliphatic epoxy compound is 15% or more, the polarity of the compound can be increased in the same manner as described above, so that the number of low-polarity components used in the head portion of the inkjet device can be reduced. Deterioration of adhesives, etc. (damage to the device). From the viewpoint of further reducing damage to the device, the oxygen atom content of the (C) aliphatic epoxy compound is preferably 20% or more. From the viewpoint of not increasing the dielectric constant of the sealing layer too much, the oxygen atom content is preferably, for example, 30% or less. The oxygen atom content can be defined and measured in the same manner as above.

In order to increase the oxygen atom content of the (C) aliphatic epoxy compound, for example, the number of epoxy groups and the number of oxygen atom-containing groups (for example, polyoxyalkylene groups, etc.) in one molecule of the compound can be increased. Can.

Such (C) aliphatic epoxy compounds are glycidyl ethers of aliphatic alcohols (including polyhydric alcohols) not having an aromatic ring as described above. Aliphatic alcohols (including aliphatic polyhydric alcohols) may be chain or cyclic. Among them, the (C) aliphatic epoxy compound does not have a cycloolefin oxide structure. Among these, aliphatic alcohols (including aliphatic polyhydric alcohols) are preferably chain-like from the viewpoint of making the sealing agent more easily low-viscosity.

(C) The number of epoxy groups in one molecule of the aliphatic epoxy compound may be one (monofunctional) or two or more (polyfunctional). Among them, two or more are preferable (polyfunctional) from the viewpoints of easily increasing the oxygen atom content and improving curability.

That is, (C) the aliphatic epoxy compound is preferably polyglycidyl ether of aliphatic polyhydric alcohol or its alkylene oxide adduct, more preferably diglycidyl ether of alkanediol or its alkylene oxide adduct .

(C) Examples of aliphatic epoxy compounds include: 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether, etc. Diglycidyl ether of alkane diol; triglycidyl ether of glycerin and trimethylolpropane; tetraglycidyl ether of sorbitol; hexaglycidyl ether of dipentaerythritol; Glycidyl ether; a polyglycidyl ether of an alkylene oxide adduct (polyether polyol) such as propylene glycol or trimethylolpropane, in which the weight average molecular weight and oxygen atom content satisfy the above-mentioned ranges. Examples of commercially available products include: SR-PG, SR-2EGS, SR-8EGS, SR-14BJ, SY-25L (manufactured by Sakamoto Pharmaceutical Co., Ltd.), Epogosey 2EH, Epogosey HD (D), Epogosey NPG (D), Epogosey BD (D) (manufactured by Yokkaichi Gosei Co., Ltd.), Denacol EX-121, Denacol ) EX-212L, Denacol EX-214L (manufactured by Nagase ChemteX).

(C) It is preferable that content of an aliphatic epoxy compound is 5 mass % - 60 mass % with respect to the gross mass of a sealing agent. When the content of the (C) aliphatic epoxy compound is 5% by mass or more, it is easy to sufficiently reduce the viscosity of the sealant and to provide sufficient flexibility or adhesiveness to the cured product. If it is 60% by mass or less, it is difficult to damage sclerosis. From such viewpoints, the content of the (C) aliphatic epoxy compound is more preferably from 5% by mass to 50% by mass, more preferably from 10% by mass to 40% by mass, relative to the total mass of the sealant.

In this way, by combining (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, and (C) an aliphatic epoxy compound, the volatilization of the sealant will not be excessively increased. Viscosity can be set to sufficiently low, which can effectively improve hardenability. In addition, it is difficult to swell the rubber material and the like of the head portion of the inkjet device, and damage to the inkjet device can be reduced.

(C) The content of the aliphatic epoxy compound is preferably larger than the content of the (A) alicyclic epoxy compound having a cycloolefin oxide structure. Specifically, the content ratio (C/A) of the (C) aliphatic epoxy compound to the (A) alicyclic epoxy compound having a cycloolefin oxide structure is preferably from 0.5 to 1.5. Thereby, the sealant can have a sufficiently low viscosity, and the flexibility and adhesiveness of the cured product can be further improved.

The (B) content of the oxetane compound is preferably larger than the content of the (C) aliphatic epoxy compound. Specifically, the ratio (B/C) of the content of the (B) oxetane compound to the (C) aliphatic epoxy compound is preferably 0.5-7. Thereby, the viscosity of the sealant can be set lower and the curability can be further improved. Thereby, the discharge property of the inkjet method can be further improved, and the curing after coating can be rapidly advanced, and the sagging on the object to be coated can be easily suppressed.

In addition, from the viewpoint of further reducing damage to the inkjet device, (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, and (C ) aliphatic epoxy compounds are respectively polyfunctional compounds, more preferably difunctional compounds. In addition, one or more of (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, and (C) an aliphatic epoxy compound is preferred, preferably (A) The alicyclic epoxy compound has a carbonyloxy group (or an ester group). The reason is that the carbonyloxy group (or ester group) has high polarity even among oxygen-containing groups, and it is difficult to swell low-polarity rubber materials and the like used in the head of the inkjet device, which can further reduce damage.

＜(D) Cationic polymerization initiator＞ (D) The cationic polymerization initiator can be a photocationic polymerization initiator that generates an acid that can start cationic polymerization when irradiated with light such as ultraviolet rays, or a thermal cationic polymerization initiator that generates an acid by heating . Among them, from the viewpoint of reducing damage to the display element by heating, it is preferable to photocure the sealing agent, and the (D) cationic polymerization initiator is preferably a photocationic polymerization initiator.

The photocationic polymerization initiator can be an aromatic part with BF ₄ ^- , PF ₆ ^- , SbF ₆ ^- , or BX ₄ ^- (X is a phenyl group substituted by at least two fluorine or trifluoromethyl) Perdium salt, aromatic iodonium salt, aromatic diazonium salt, aromatic ammonium salt.

Examples of aromatic cobaltium salts include: bis[4-(diphenylpermeyl)phenyl]sulfide bishexafluorophosphate, bis[4-(diphenylpermeyl)phenyl]sulfide bishexafluoroantimony bis[4-(diphenylpermeyl)phenyl]sulfide bistetrafluoroborate, bis[4-(diphenylpermeyl)phenyl]sulfide tetrakis(pentafluorophenyl)borate , Diphenyl-4-(phenylsulfanyl)phenylsulfurium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfurium hexafluoroantimonate, diphenyl-4-(phenylthio ) Phenyl percite tetrafluoroborate, etc.

Examples of aromatic iodonium salts include: diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, diphenyliodonium tetrafluoroborate, diphenyliodonium tetrakis(pentafluorophenyl)borate, Bis(dodecylphenyl)iodonium hexafluorophosphate, bis(dodecylphenyl)iodonium hexafluoroantimonate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium tetrafluoroborate, bis(dodecylphenyl)iodonium ) Tetrakis (pentafluorophenyl) borate, etc.

Examples of aromatic diazonium salts include: phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, phenyldiazonium tetrakis(pentafluoro Phenyl) borate, etc.

Examples of the aromatic ammonium salt include: 1-benzyl-2-cyanopyridinium hexafluorophosphate, 1-benzyl-2-cyanopyridinium hexafluoroantimonate, and the like.

Examples of photocationic polymerization initiators include: Irgacure 250, Irgacure 270, Irgacure 290 (manufactured by BASF), CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG (manufactured by San-Apro), SP-150, SP-170, SP-171, SP-056, SP-066, SP-130 , SP-140, SP-601, SP-606, SP-701 (manufactured by ADEKA). Among them, Irgacure 270, Irgacure 290, CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG, SP-150, SP are preferred -170, SP-171, SP-056, SP-066, SP-601, SP-606, SP-701 and other cerium salts.

(D) It is preferable that content of a cationic polymerization initiator is 0.1 mass % - 10 mass % with respect to the mass of the sealing agent whole. When the content of the (D) cationic polymerization initiator is 0.1% by mass or more, it is easy to improve the curability of the sealant, and when it is 10% by mass or less, it is easy to suppress the coloring of the sealant layer. From such viewpoints, the content of the (D) cationic polymerization initiator is more preferably 0.1% by mass to 5% by mass based on the total mass of the (A) component, (B) component, (C) component, and (E) component. % by mass, more preferably 0.1% by mass to 3% by mass.

＜(E) Other ingredients＞ The sealing compound for display elements of this invention may further contain other components other than (A) component - (D)component in the range which does not impair the effect of this invention. Examples of other ingredients include: aromatic epoxy compounds, sensitizers, silane coupling agents, leveling agents, and the like.

Aromatic epoxy compounds are glycidyl ethers of alcohols (including polyhydric alcohols) containing aromatic rings. Examples of aromatic epoxy compounds include: bisphenol A type epoxy resin, bisphenol E type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, bisphenol O type epoxy resin, 2 ,2'-diallyl bisphenol A type epoxy resin, propylene oxide addition bisphenol A type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, thioether type ring Oxygen resin, diphenyl ether type epoxy resin, naphthalene type epoxy resin, phenol novolak type epoxy resin, o-cresol novolac type epoxy resin, biphenyl novolac type epoxy resin, naphthalenephenol ) Novolak type epoxy resin, etc.

The oxygen atom content or the weight average molecular weight of the aromatic epoxy compound is not particularly limited, but from the viewpoint of reducing the volatility of the sealant or damage to the device, similarly to (A) component to (C) component, The oxygen atom content is preferably at least 15%, and the weight average molecular weight is preferably at least 180.

Among them, if the sealing agent contains a large amount of bisphenol A type, F type epoxy resin, etc., the viscosity will become high easily. In addition, when the sealant contains a large amount of aromatic epoxy resin, the cured product of the sealant may be easily colored. Therefore, it is preferable to adjust the content of the aromatic epoxy resin so as to have little influence on the viscosity of the sealant or the coloring of the cured product.

The sensitizer may have a function of further increasing the polymerization initiation efficiency of the polymerization initiator and further accelerating the hardening reaction of the sealant. Examples of sensitizers include: thioxanthone-based compounds such as 2,4-diethylthioxanthone, or 2,2-dimethoxy-1,2-diphenylethan-1-one, diphenyl Methanone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4,4'-bis(dimethylamino)benzophenone, 4-benzoyl-4 '-Methyl diphenyl sulfide, etc.

The silane coupling agent has the function of further improving the adhesion between the sealant and the substrate. The silane coupling agent can be a silane compound having reactive groups such as epoxy groups, carboxyl groups, methacryl groups, and isocyanate groups. Examples of such silane compounds include: trimethoxysilylbenzoic acid, γ-methacryloxypropyltrimethoxysilane, vinyltriacetyloxysilane, vinyltrimethoxysilane, γ-iso Cyanatopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. These silane compounds may be used alone or in combination of two or more.

The leveling agent may have a function of imparting flatness to the coating film to the sealant. Examples of leveling agents include silicone-based, acrylic-based, and fluorine-based leveling agents. Examples of commercially available leveling agents include: BYK-340, BYK-345 (all manufactured by BYK Chemie Japan), Surflon S-611 (AGC Seimi Chemical) company).

From the viewpoint of suppressing volatilization of the sealant and reducing damage to the device, the total content of other components (E) is preferably at most 20% by mass, more preferably at most 10% by mass, based on the total mass of the sealant.

＜Physical properties of sealant＞ (viscosity) The viscosity of the sealant for a display device measured with an E-type viscometer at 25° C. and 20 rpm is preferably 50 mPa·s or less, more preferably 20 mPa·s or less. When the viscosity of a sealing compound is the said range, the discharge property at the time of apply|coating a sealing compound by an inkjet method becomes favorable easily. The lower limit of the viscosity of the sealant may be, for example, 5 mPa·s.

(light transmittance) The average value of the light transmittance at a wavelength of 380 nm to 800 nm is preferably at least 85%, more preferably at least 90%, of the light transmittance at a thickness of 10 μm of the cured product of the sealant for a display element. If the light transmittance of the hardened|cured material of the sealing compound for display elements is the said range, since it has favorable light transmittance, it is suitable as a surface sealing compound of an organic EL element, for example. The average light transmittance can be measured, for example, using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation) as an average value of light transmittance measured per 1 nm of wavelength at a wavelength of 380 nm to 800 nm.

(Oxygen atom content rate) From the viewpoint of highly reducing damage to the device, the oxygen atom content of the sealing agent for a display device is preferably 15% or more, more preferably 20% or more, as described above. From the viewpoint of not making the dielectric constant of the sealing layer too large, the oxygen atom content of the sealing compound for display elements is preferably, for example, 30% or less. The oxygen atom content of the sealant for display elements can be calculated as (total mass of oxygen atoms contained in sealant for display elements/total mass of sealant for display elements)×100 (%). The total mass of oxygen atoms contained in the sealant for display elements can be calculated by calculating the ratio of oxygen atoms contained in the sealant for display elements by elemental analysis and multiplying this by the atomic weight of oxygen atoms.

＜Preparation method of sealant＞ The sealing agent for display elements can be obtained by mixing at least (A) component - (D) component using mixers, such as a homodisper, a homomixer, a universal mixer, a planetary mixer, a kneader, and three rolls, for example. Furthermore, after mixing (A) component - (C)component, it is preferable to add (D)component and mix from a viewpoint of mixing a sealing agent stably.

The sealing agent for display elements can be used as a surface sealing agent for display elements, preferably a surface sealing agent for organic EL elements.

2. Display device The display device of the present invention includes a display element disposed on a substrate, and a cured product layer of the sealing agent for display elements of the present invention that seals the display element in a planar shape.

The substrate can be a glass substrate or a resin substrate. From the viewpoint of obtaining a flexible optical semiconductor device, a resin substrate (resin film) is preferable.

A display element is an element that converts electricity into light or light into electricity. Examples of display elements include organic EL elements, light emitting diode (Light Emitting Diode, LED) elements, and the like. Among them, the display element is preferably an organic EL element.

The thickness of the hardened layer of the sealant for display elements is not particularly limited as long as it can sufficiently seal the display elements and achieve flatness or thin film properties. For example, it is preferably 5 μm to 20 μm, and may be 5 μm μm～10 μm.

Such a display device can be produced by any method. For example, a display device can be manufactured through the following steps: 1) a step of obtaining a display element arranged on a substrate; 2) a step of applying the sealant for a display element of the present invention in a planar form on the display element; and 3) A step of hardening the applied encapsulant for display elements.

1) In the step, a substrate on which a display element is arranged is prepared. When the display element is an organic EL element, the organic EL element generally includes a reflective pixel electrode layer, an organic EL layer, and a transparent opposite electrode layer, and may further include other functional layers as required.

2) In the process, the sealing compound for display elements of this invention is apply|coated so that the display element arrange|positioned on the board|substrate may be covered. The application|coating of the sealing agent for display elements can be performed by arbitrary methods, for example, a screen printing method, an inkjet method, etc. are performed. Among these, the inkjet method is preferable from the viewpoint of being able to form a uniform coating layer having high flatness and a thin film at high speed. That is, it is preferable to provide the sealing compound for display elements of this invention on a display element by the inkjet method, and to coat it in a planar shape.

3) In the step, the sealant coated on the display element is hardened to obtain a hardened layer. The curing of the sealant is preferably photocuring, and may be further thermally cured.

In the case of photocuring, well-known light sources, such as a xenon lamp and a carbon arc lamp, can be used as a light source used for light irradiation, for example. The light irradiation is not particularly limited as long as it can sufficiently harden the sealant. For example, it can be irradiated with light with a wavelength of 300 nm to 400 nm at a cumulative light intensity of 300 mJ/m ² to 3000 mJ/m ² . Properly hardened.

In the case of further thermosetting, the heating temperature is preferably, for example, 50° C. to 120° C. from the viewpoint of reducing damage to a display element and sufficiently curing.

The obtained display device is, for example, an organic EL device or the like, and can be preferably used as various display devices or lighting devices. [Example]

Hereinafter, the present invention will be described in more detail with reference to examples. The scope of the present invention is not limitedly interpreted by these Examples.

·賽羅西德（Celloxide）CEL 8000（大賽璐（Daicel）公司製造，氧原子含有率16.49%，分子量194） [化6]

1. Material of sealant (A) Alicyclic epoxy compound having cycloolefin oxide structure Celloxide CEL 2021P (manufactured by Daicel, 3',4'-epoxy ring Hexylmethyl 3,4-epoxycyclohexanecarboxylate, oxygen atom content 25.4%, molecular weight 252) [Chem. 5]

・Celloxide CEL 8000 (manufactured by Daicel, oxygen atom content 16.49%, molecular weight 194) [Chemical 6]

·賽羅西德（Celloxide）CEL 2000（大賽璐（Daicel）公司製造，1,2-環氧-4-乙烯基環己烷，氧原子含有率12.9%，分子量124） [化8]

(A') Comparative compound LDO (manufactured by Symrise, limonene dioxide, oxygen atom content 19.05%, molecular weight 168) [Chemical 7]

・Celloxide CEL 2000 (manufactured by Daicel, 1,2-epoxy-4-vinylcyclohexane, oxygen atom content 12.9%, molecular weight 124) [Chem. 8]

(B) Oxetane compound OXT-221 (manufactured by Toagosei Co., Ltd., 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxy Heterocyclobutane, oxygen atom content 22.43%, molecular weight 214) [Chemical 9]

·OXT-212 （東亞合成公司製造，2-乙基己基氧雜環丁烷，氧原子含有率14.04%，分子量228）(B') Comparative compound AL-OX (manufactured by Yokkaichi Gosei Co., Ltd., oxygen atom content 28.07%, molecular weight 114) [Chem. 10]

・OXT-212 (manufactured by Toagosei Co., Ltd., 2-ethylhexyloxetane, oxygen atom content 14.04%, molecular weight 228)

(C) Aliphatic epoxy compound ・SR-16HL (manufactured by Sakamoto Pharmaceutical Co., Ltd., 1,6-hexanediol diglycidyl ether, epoxy equivalent 125 g/eq, oxygen atom content 27.83%, molecular weight 230)

(C') Compounds for comparison ・EX-111 (manufactured by Nagase ChemteX Co., Ltd., allyl glycidyl ether, oxygen atom content 13.22%, molecular weight 242) ・SY-35M (manufactured by Sakamoto Pharmaceutical Co., Ltd., high-grade alcohol glycidyl ether, oxygen atom content 28.07%, molecular weight 114, epoxy equivalent 280 g/eq)

In addition, the oxygen atom content rate of a compound is calculated from a structural formula. In addition, the molecular weight of a compound is calculated from a structural formula.

X^- =PF₆ ^- (D) Cationic polymerization initiator CPI-200K (manufactured by San-Apro, diphenyl-4-(phenylsulfanyl)phenyl percolium hexafluorophosphate, refer to the following formula) [Chem. 11 ]

X ^- =PF ₆ ^-

(E) Aromatic epoxy compounds ・EX-201 (manufactured by Nagase ChemteX Co., Ltd., resorcinol diglycidyl ether, oxygen atom content 28.8%, molecular weight 222)

2. Preparation and Evaluation of Sealants (Example 1 to Example 4, Comparative Example 1 to Comparative Example 9) In such a manner that the composition shown in Table 1 was obtained, an alicyclic epoxy compound having a cycloolefin oxide structure, an oxetane compound, an aliphatic epoxy compound, and an aromatic epoxy compound as needed were put into flask and mix. The cationic polymerization initiator of the quantity shown in Table 1 was put into the obtained mixture, and it mixed. In the obtained mixture, stirring was performed until no powdery matter was seen, thereby obtaining a sealant.

The viscosity, swelling property (damage to the device), volatility, and curability of the obtained sealant were evaluated by the following methods.

[viscosity] The viscosity of the obtained sealant was measured at 25° C. and 20 rpm using an E-type viscometer (manufactured by Brookfield, LV-DV-II+). ○: 10 mPa·s or more and 20 mPa·s or less △: More than 20 mPa·s and less than 50 mPa·s ×: over 50 mPa·s

[swellability] The weight of an EPDM O-ring (EPDM-70, AS568-009 specification), which is a rubber material used in the head portion of the inkjet device, was measured. Next, the EPDM O-ring whose weight was measured was immersed in the sealant, and it stored at 25 degreeC under light-shielding for 1 week. After storage, take out the EPDM O-ring and measure the weight. Then, the weight change rate was calculated by applying it to the following formula. Weight change rate (%) = [(weight after storage - weight before storage) / weight before storage] × 100 And, swelling property was evaluated based on the following criteria. ◎: The weight change rate is less than 5% ○: Weight change rate exceeds 5% and is 10% or less △: The weight change rate exceeds 10% and is 15% or less ×: Weight change rate exceeds 15%

[volatility] The volatility of the sealant was measured using a differential thermogravimetric simultaneous measurement device (thermogravimetric-differential thermal analysis, TG-DTA). Specifically, after raising the temperature of the sealing agent from 30° C. to 50° C. at 5° C./minute, the temperature was maintained for 50 minutes. And the weight reduction rate ((weight after heating-weight before heating)/weight before heating)×100) of the sealing agent after holding|maintaining for 50 minutes was measured. And the volatility was evaluated by the following reference|standard. ○: Weight reduction rate is less than 1% ×: The weight reduction rate is 1% or more

[Curability] At room temperature, the sealant was coated on a glass substrate using a bar coater (No. 6), and dried to form a coating film with a thickness of 10 μm. The obtained coating film was placed in a N ₂ flushing box, and nitrogen was circulated for 1 minute, and the system was replaced with nitrogen. Next, the obtained coating film was irradiated with UV light having a wavelength of 365 nm using a UV (ultraviolet)-LED lamp so that the cumulative irradiation dose was 1000 mJ/m ² . Furthermore, the irradiated part of the coating film was touched with a finger, and the presence or absence of stickiness was judged. ○: No stickiness ×: Stickiness remains when touched with fingers

[Average Light Transmittance of Cured Material] The obtained sealant was introduced into an inkjet cartridge DMC-11610 (manufactured by Fujifilm Dimatix). This inkjet cartridge was installed in an inkjet device DMP-2831 (manufactured by Fujifilm Polaris (Dimatix) Co., Ltd.), and after adjusting the ejection state, it was placed on a SiN substrate so that the thickness after curing was 10 μm at a distance of 5 cm× 5 cm size for coating. After the obtained coating film was left to stand at room temperature (25° C.) for 1 minute, it was irradiated with UV light (irradiation intensity: 1000 mJ/cm ² ) to be cured. The light transmittance at a wavelength of 380 nm to 800 nm of the obtained cured product of the sealant was measured using an ultraviolet-visible spectrophotometer (manufactured by Shimadzu Corporation) for every wavelength of 1 nm, and the average value thereof was defined as " Average Light Transmittance".

Table 1 shows the compositions and evaluation results of the sealants of Examples 1 to 4 and Comparative Examples 1 to 9. In addition, the unit of the numerical value of an Example and a comparative example is a mass part.

[Table 1]

As shown in Table 1, it can be seen that the sealants of Examples 1 to 4 containing (A) to (C) and having an oxygen atom content of 15% or more and a weight average molecular weight of 180 or more have low Viscosity, low volatility and high hardening, and low swelling, can reduce the damage to the device.

On the other hand, even the sealants of Comparative Example 3, Comparative Example 6, and Comparative Example 9 in which any one of (A) to (C) had an oxygen atom content rate of less than 15% showed a high swelling property, and had a negative effect on The damage to the device is large. Even the sealing agents of Comparative Example 2, Comparative Example 5, and Comparative Example 8 in which any one of (A) to (C) had a weight average molecular weight of less than 180 suggested that volatility was high. Moreover, it turned out that the hardenability of the sealing compound of the comparative example 1 which does not contain (A) component, and the comparative example 4 which does not contain (B) component is low. Moreover, it turned out that the swelling property of the comparative example 7 which does not contain (C)component is inferior.

This application claims priority based on Japanese Patent Application No. 2018-116842 filed on June 20, 2018. All the content described in this application specification is used for this application specification. [industrial availability]

According to the present invention, there can be provided a sealant for a display element having low viscosity, low volatility, and good curability suitable for coating by an inkjet method, and a cured product thereof, and a cured product thereof. There is less damage to the inkjet device.

none

none

Claims (7)

A sealant for display elements, comprising: (A) an alicyclic epoxy compound having a cycloolefin oxide structure, (B) an oxetane compound, and (C) an aliphatic epoxy compound, wherein, with the The alicyclic epoxy compound is different, and (D) cationic polymerization initiator, and the (A) alicyclic epoxy compound, the (B) oxetane compound, and the (C) fatty The weight-average molecular weights of the epoxy compounds are respectively more than 180, and the oxygen atom content rates represented by the following formula (1) are respectively more than 15%; the (B) oxetane compound is ) the content ratio (B/C) of the aliphatic epoxy compound is 3.25 to 7 (mass ratio), and the (C) aliphatic epoxy compound has a cycloalkene oxide structure with respect to the (A) alicyclic The content ratio (C/A) of the formula epoxy compound is 0.5~1.5 (mass ratio), the oxygen atom content ratio (%)=the total mass of oxygen atoms in 1 molecule/weight average molecular weight×100...(1) . The sealant for display elements as described in Claim 1 of the patent application, wherein the (A) alicyclic epoxy compound, the (B) oxetane compound, and the (C) alicyclic The oxygen compounds are respectively polyfunctional compounds. The sealant for display elements as described in item 1 of the scope of the patent application, wherein One or more of the (A) alicyclic epoxy compound, the (B) oxetane compound, and the (C) aliphatic epoxy compound have a carbonyloxy group. The sealant for display elements as described in Item 1 of the scope of the patent application, wherein the viscosity measured by an E-type viscometer at 25°C and 20rpm is 50mPa. below s. The sealing compound for display elements as described in Claim 1 used for coating by the inkjet method. The sealant for a display element as described in claim 1 of the patent claims, wherein the organic electroluminescence element as the display element is sealed in a planar shape. A cured product, which is a cured product of the sealant for display elements described in claim 1 of the patent application.