TWI816853B - sealant - Google Patents

Abstract

An object of the present invention is to provide a sealant that has a viscosity suitable for coating by an inkjet method, suppresses damage to the inkjet head of an inkjet device, and has a cured product with a low dielectric constant. Solve the problem by using a sealant containing (A) an alicyclic epoxy compound having two or more ethylhexyl groups, (B) a multifunctional oxetane compound, and (C) a monofunctional glycidyl ether. Describe the topic.

Description

sealant

The present invention relates to a sealant.

In recent years, display devices using display elements such as organic electroluminescence elements (hereinafter referred to as organic EL (electroluminescence) elements) have been developed. However, display elements are generally easily deteriorated by moisture or oxygen in the atmosphere. Therefore, in various display devices, the display elements are usually sealed by a sealing layer (surface sealing). In addition, sealants are also used to seal various elements such as solar cell elements and semiconductor elements.

For example, in a device including various elements such as an organic EL element, the element such as the organic EL element may be surface-sealed with a cured product of a sealant containing a curable resin. Previously, sealants were usually applied (printed) using a screen printing method. However, in recent years, in order to achieve flexibility of the device, there has been a demand for flattening or thinning the cured product of the sealant (hereinafter also referred to as “sealing layer”). Therefore, research has been conducted on using the inkjet method to apply sealants. When the sealant is applied using an inkjet device, it is required that the sealant be ejected from the nozzle stably over a long period of time. In addition, it is required to suppress swelling of the adhesive or rubber material used in the head portion of the inkjet device and to cause less damage to the device.

Here, as a composition for coating with an inkjet device, a composition containing an epoxidized vegetable oil, an alicyclic epoxy group-containing compound, an oxetanyl group-containing compound, and a photocationic polymerization initiator is proposed. agent inkjet composition (for example, Patent Document 1). [Prior art documents] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2016-108512

[Problem to be solved by the invention] However, the surface sealant described in Patent Document 1 is difficult to apply stably from an inkjet device.

In addition, in recent years, display devices with touch panels have been widely spread. In this display device, the display element sealed by the sealing layer and the sensor such as the touch panel are arranged close to each other. Furthermore, if the thickness of the sealing layer becomes thinner, interference between the display element and the sensor may easily occur, and the operation of the display device may become unstable. In order to prevent such operational instability, it is desirable that the sealing layer has a low dielectric constant.

The present invention was made in view of the above-mentioned circumstances, and an object thereof is to provide a sealant suitable for long-term and stable application by the inkjet method. [Means to solve the problem]

The present invention provides the following sealants. [1] A sealant containing: (A) an alicyclic epoxy compound having two or more ethylhexyl groups, (B) a multifunctional oxetane compound, and (C) a monofunctional glycidyl ether. [2] The sealant as described in [1], wherein the viscosity measured using an E-type viscometer at 25°C and 20 rpm is 8 mPa·s to 40 mPa·s. [3] The sealant according to any one of [1] or [2], wherein (A) the alicyclic epoxy compound having two or more ethylhexyl groups is represented by the following formula (I) Epoxy hexahydrophthalate di-2-ethylhexyl, [Chemical 1] . [4] The sealant according to any one of [1] to [3], wherein the (C) monofunctional glycidyl ether is a phenyl glycidyl ether derivative. [5] The sealant according to any one of [1] to [4], wherein the ethylene-propylene-diene rubber test piece is immersed in the (C) monofunctional glycidyl ether at 25°C for one week The swelling rate A of the ethylene-propylene-diene rubber, represented by the weight change rate of the test piece before and after immersion, is 5% or less. [6] The sealant according to any one of [1] to [5], wherein the (C) monofunctional glycidyl ether is measured using an E-type viscometer at 25°C and 20 rpm. The viscosity is below 35 mPa·s. [7] The sealant according to any one of [1] to [6], wherein the ethylene-propylene-diene rubber test piece is immersed in the sealant at 40° C. for one week. The swelling rate B of the ethylene-propylene-diene rubber represented by the weight change rate of the test piece before and after immersion is 10% or less. [8] The sealant according to any one of [1] to [7], wherein an ultraviolet-light emitting diode (UV-LED) lamp with a wavelength of 395 nm is used for the sealant After ultraviolet curing under the conditions of illumination: 1000 mW/cm ² and cumulative light intensity: 1500 mJ/cm ² , the cured product obtained by thermal curing at 100°C for 30 minutes has a dielectric constant of 3.10 at a frequency of 100 kHz. the following. [9] The sealant according to any one of [1] to [8], which is used for a display element. [10] The sealant according to any one of [1] to [9], which is used for coating by the inkjet method. [11] The sealant according to [10], wherein the display element is an organic electroluminescent element. [Effects of the invention]

According to the present invention, a sealant suitable for coating by the inkjet method can be provided.

1. Sealant The sealant of the present invention is a sealant used for surface sealing of various elements such as display elements, solar cell elements, and semiconductor elements, or for sealing liquid crystal of a liquid crystal display element. This sealant contains (A) an alicyclic epoxy compound having two or more ethylhexyl groups, (B) a polyfunctional oxetane compound, and (C) a monofunctional glycidyl ether. If necessary, components other than these may be included. For example, (D) cationic polymerization initiator, (E) various additives, etc. may also be included.

As a result of diligent research, the present inventors found that by appropriately combining (A) an alicyclic epoxy compound having two or more ethylhexyl groups, (B) a polyfunctional oxetane compound, and (C) Monofunctional glycidyl ether can set the viscosity of the sealant to a value suitable for inkjet coating. In addition, they found that by suppressing the swelling of the adhesive or rubber material used in the inkjet head of the inkjet device, the deformation of the inkjet head is suppressed, so that the sealant can be ejected stably over a long period of time. Furthermore, it was also found that the dielectric constant of the cured product of the sealant can be lowered.

The reason for this is not clear, but it is speculated as follows. Adhesives or rubber materials used in the head portion of inkjet devices often include low-polarity materials such as ethylene-propylene-diene monomer (EPDM) rubber. On the other hand, if the sealant contains (A) a compound with a bulky structure such as an alicyclic epoxy compound having two or more ethylhexyl groups, it will be difficult for the sealant to be compatible with low-polarity rubber materials and the like. The swelling rate of the rubber material with respect to the sealant tends to decrease. In addition, if the sealant contains (B) a polyfunctional oxetane compound, the viscosity of the sealant is likely to be reduced. Furthermore, if the sealant contains (C) monofunctional glycidyl ether, the swelling rate of the adhesive, rubber material, etc. with respect to the sealant is likely to decrease. In addition, the dielectric constant of the cured product of the sealant also tends to decrease. According to this sealant, a sealing layer with high flatness and thin thickness can be stably formed over a long period of time using the inkjet method. In addition, when such a sealant is used to seal a display element, the display element is less likely to interfere with a sensor such as a touch panel and can be placed close to the sensor. Therefore, the display device can be made thinner.

Furthermore, the sealant of the present invention is particularly suitable for coating using the inkjet method, but the coating method is not limited to the inkjet method, and can also be applied using a dispenser, screen printing, spin coating, etc. cloth.

·(A) Alicyclic epoxy compound having two or more ethylhexyl groups (A) The alicyclic epoxy compound having two or more ethylhexyl groups must be a compound that has one or more alicyclic hydrocarbon structures and one epoxy group in the molecule and two or more ethylhexyl groups. , there are no special restrictions. Alicyclic epoxy compounds with two or more ethylhexyl groups have a larger structure than those with one ethylhexyl group, so it is difficult to make the rubber material that can exist in the inkjet head Swelling.

(A) The alicyclic epoxy compound having two or more ethylhexyl groups is preferably a compound that is liquid at 25°C, and the viscosity measured using an E-type viscometer at 25°C and 20 rpm is preferred It is 10 mPa·s～500 mPa·s, more preferably, it is 30 mPa·s～300 mPa·s. If the viscosity of (A) the alicyclic epoxy compound having two or more ethylhexyl groups is within this range, the viscosity of the sealant will be easily in the range described below, and the sealant will be easily coated stably by the inkjet method.

(A) The molecular weight or weight average molecular weight of the alicyclic epoxy compound having two or more ethylhexyl groups is preferably 100 to 790, more preferably 140 to 500. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) (polystyrene conversion). If the molecular weight or weight average molecular weight of (A) the alicyclic epoxy compound having two or more ethylhexyl groups is 100 or more, then (A) the alicyclic epoxy compound having two or more ethylhexyl groups is sprayed It is difficult to evaporate in the ink device. In addition, if the molecular weight or weight average molecular weight is 790 or less, the viscosity of (A) the alicyclic epoxy compound having two or more ethylhexyl groups will not increase excessively, and further, the viscosity of the sealant can be set to the above Scope.

In addition, (A) the alicyclic epoxy compound having two or more ethylhexyl groups preferably has an oxygen atom content represented by the following formula (1) of 15% or more. Oxygen atom content rate (%) = total mass of oxygen atoms in one molecule/weight average molecular weight × 100... (1)

If the oxygen atom content of (A) the alicyclic epoxy compound having two or more ethylhexyl groups is 15% or more, the polarity of the compound will be increased, making it difficult to mix with the alicyclic epoxy compound used in the head part of the inkjet device. Adhesives or rubber materials (eg, EPDM rubber, etc.) with low polarity are compatible with each other, making it difficult to swell the adhesive or rubber materials (eg, EPDM rubber, etc.). This can reduce the deterioration of the adhesive or rubber material (damage to the device). From this viewpoint, the oxygen atom content is preferably 18% or more. The upper limit of the oxygen atom content may be such that the dielectric constant of the sealing layer obtained does not increase excessively, and is preferably 30% or less, for example.

(A) The total mass of oxygen atoms in one molecule of an alicyclic epoxy compound having two or more ethylhexyl groups can be determined using Gas Chromatography-Mass Spectrometry (GC-MS) or NMR. The structure of the alicyclic epoxy compound is determined using a Nuclear Magnetic Resonance (NMR) method or the like, the number of oxygen atoms in one molecule of the compound is determined, and the number is multiplied by the atomic weight of the oxygen atom to calculate the result. Furthermore, (A) the oxygen atom content rate of the alicyclic epoxy compound having two or more ethylhexyl groups can be determined by applying the obtained total mass of oxygen atoms and the weight average molecular weight measured by the GPC method. It can be calculated from equation (1).

(A) The oxygen atom content of an alicyclic epoxy compound having two or more ethylhexyl groups can be determined, for example, by the number of epoxy groups in the molecule, or a 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.). That is, in order to reduce the oxygen atom content rate, it is preferable to reduce the number of groups having oxygen atoms in one molecule.

(A) The alicyclic epoxy compound having two or more ethylhexyl groups is preferably a compound having one cyclic olefin oxide and two ethylhexyl groups respectively bonded to the alicyclic structure. Furthermore, a compound in which two ethylhexyl groups are bonded to an alicyclic structure via an ester bond is more preferred.

Specific examples of such compounds include di-2-ethylhexyl epoxy hexahydrophthalate represented by the following formula (I). [Chemicalization 2]

Examples of commercially available products of the epoxy hexahydrophthalate di-2-ethylhexyl ester include Sansocizer E-PS (manufactured by Shinnippon Rika Co., Ltd.) and the like.

The amount of (A) the alicyclic epoxy compound having two or more ethylhexyl groups is preferably 10 to 50 mass % relative to the total mass of the sealant. If the amount of (A) the alicyclic epoxy compound having two or more ethylhexyl groups is 10 mass % or more, the dielectric constant of the sealant is likely to decrease. On the other hand, if it is 50% by mass or less, the viscosity of the sealant becomes an appropriate value, and the swelling rate of the adhesive or rubber material used in the inkjet head part with respect to the sealant is easily reduced. Furthermore, as the amount of the polyfunctional oxetane compound (B) increases relatively, the dielectric constant tends to become lower. The content of (A) the alicyclic epoxy compound having two or more ethylhexyl groups is more preferably 10% by mass to 40% by mass, and further preferably 15% by mass to 30% by mass relative to the total mass of the sealant.

·(B) Multifunctional oxetane compounds (B) The polyfunctional oxetane compound may be a bifunctional or higher compound having two or more oxetanyl groups, and preferably has a molecular weight or a weight average molecular weight of 180 or more. In addition, the oxygen atom content represented by the formula (1) is preferably 15% or more.

If the weight average molecular weight of the polyfunctional oxetane compound (B) is 180 or more, the volatility of the compound can be reduced. Therefore, it is possible to reduce deterioration of the working environment and damage to the object to be coated (display element) when applying the sealant using the inkjet method. From the viewpoint of reducing the volatility of the sealant, the weight average molecular weight of the polyfunctional oxetane compound (B) is preferably 190 or more, more preferably 200 or more. The upper limit of the weight average molecular weight only needs to be a level that does not impair the ejectability of the sealant when applied by the inkjet method, and is more preferably 400 or less, for example. The weight average molecular weight can be measured using the same method as described above.

If the oxygen atom content of the polyfunctional oxetane compound (B) is 15% or more, the polarity of the compound can be increased, thereby reducing the need for low-polarity adhesives or rubbers used in the head portion of the inkjet device. Deterioration of materials, etc. (damage to equipment). From the viewpoint of reducing damage to the device, the oxygen atom content of the polyfunctional oxetane compound (B) is preferably 20% or more. From the viewpoint that the dielectric constant of the sealing layer does not increase excessively, the oxygen atom content is preferably 30% or less, for example. The oxygen atom content is defined and measured in the same manner as described above.

The polyfunctional oxetane compound (B) is preferably a liquid compound at 25°C, and the viscosity measured using an E-type viscometer at 25°C and 20 rpm is preferably 1 mPa·s~ 500 mPa·s, preferably 1 mPa·s～300 mPa·s. If the viscosity of the polyfunctional oxetane compound (B) is within this range, the viscosity of the sealant will be easily within the above range, and the sealant will be easily coated stably by the inkjet method.

In order to increase the oxygen atom content of the polyfunctional oxetane compound (B), for example, the number of oxetanyl groups in one molecule of the compound may be increased, or the group containing oxygen atoms may be increased (for example, the following formula ( B-1) The number of polyoxyalkylene groups represented by R ₂ , or oxygen atoms contained in R ₂ , or groups containing oxygen atoms such as carbonyl groups or sulfonyl groups) is sufficient.

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

[Chemical 3] Formula (II-1) Formula (II-2)

R ₁ in formula (II-1) and formula (II-2) is respectively 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. 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 (II-1) and formula (II-2) satisfy the above ranges.

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

Examples of the divalent organic residue include an alkylene group, a polyoxyalkylene group, a phenylene group, a xylylene group, and a structure represented by the following formula. [Chemical 4] ,

R ₃ in the formula 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 group or aryl group having 1 to 6 carbon atoms. Examples of the alkylene group include alkylene groups having 1 to 15 carbon atoms, such as methylene, ethylene, propylene, butylene, and cyclohexylene. The polyoxyalkylene group is preferably a polyoxyalkylene group having 4 to 30 carbon atoms, preferably 4 to 8 carbon atoms, and examples thereof include polyoxyethylene and polyoxypropylene.

Examples of the compound represented by the general formula (II-2) include 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane and the like , examples of commercially available products include Arone Oxetane OXT-221 (manufactured by Toa Gosei Co., Ltd.), etc.

The amount of the polyfunctional oxetane compound (B) is preferably 20% by mass to 80% by mass relative to the total mass of the sealant. If the content of the polyfunctional oxetane compound (B) is 20% by mass or more, it is easy to sufficiently reduce the viscosity of the sealant and to improve the hardenability. If it is 80% by mass or less, it is easy to suppress the component (A) or ( C) Reduction in hardening properties caused by excessive reduction in ingredients. From this viewpoint, the content of the polyfunctional oxetane compound (B) is more preferably 25% by mass to 80% by mass, and further preferably 30% by mass to 70% by mass relative to the total mass of the sealant.

·(C) Monofunctional glycidyl ether The sealant in turn contains (C) monofunctional glycidyl ether. (C) The monofunctional glycidyl ether is a compound containing only one glycidyl ether group, and the group bonded to the glycidyl ether group may be any of aliphatic, alicyclic, and aromatic. (C) The monofunctional glycidyl ether has a bulky structure, so when contained in the sealant, the swelling rate of the rubber material with respect to the sealant decreases. In addition, (C) monofunctional glycidyl ether is a compound with a low oxygen content. Therefore, when contained in a sealant, the dielectric constant of the cured product of the sealant decreases.

(C) Examples of monofunctional glycidyl ether include: methyl glycidyl ether, ethyl glycidyl ether, propyl glycidyl ether, n-butyl glycidyl ether, octyl glycidyl ether, and 2-ethylhexyl glycidyl ether. Ether, decyl glycidyl ether, dodecyl glycidyl ether, stearyl glycidyl ether, ethoxybutyl glycidyl ether, 1-allyloxy-2,3-epoxypropane, 1-( 1',1'-Dimethylpropargyloxy)-2,3-epoxypropane, phenyl glycidyl ether, cresolyl glycidyl ether, butylphenyl glycidyl ether, naphthyl glycidyl ether , phenylphenol glycidyl ether, benzyl alcohol glycidyl ether, etc.

(C) The monofunctional glycidyl ether is preferably a compound in which a glycidyl ether group is bonded to an aromatic group, and more preferably a phenyl glycidyl ether derivative in which the aromatic group is a phenyl group. Examples of phenyl glycidyl ether derivatives include: phenyl glycidyl ether, o-cresolyl glycidyl ether, m-p-cresolyl glycidyl ether, butylphenyl glycidyl ether, and tert-butylphenyl glycidyl ether. Ether, phenylphenol glycidyl ether, etc. The phenyl glycidyl ether derivative has a bulky structure among the monofunctional glycidyl ethers, so it is easy to exert the effect of reducing the swelling rate.

Furthermore, (C) monofunctional glycidyl ether is preferably the weight change rate of the test piece before and after the immersion, which occurs when an EPDM test piece is immersed in (C) monofunctional glycidyl ether for one week at 25°C. The indicated swelling ratio A of the ethylene-propylene-diene rubber is 5% or less. By using such (C) monofunctional glycidyl ether, the swelling rate of rubber materials such as EPDM rubber or adhesives used in the inkjet head with respect to the sealant can be reduced. The swelling ratio A can be measured by the method described below.

(C) The monofunctional glycidyl ether preferably has a viscosity of 35 mPa·s or less measured using an E-type viscometer at 25°C and 20 rpm. If the viscosity of (C) the monofunctional glycidyl ether is within the above range, the viscosity of the sealant will be easily within the range described below, and the sealant will be easily coated stably by the inkjet method. (C) The viscosity of the monofunctional glycidyl ether is more preferably 3 mPa·s to 30 mPa·s, and further preferably 5 mPa·s to 25 mPa·s. If the viscosity of the sealant is 3 mPa·s or more, the curability of the sealant increases, and the dielectric constant of the cured product is easily reduced.

The amount of (C) monofunctional glycidyl ether is preferably 5 to 50 mass% relative to the total mass of the sealant. If the amount of (C) monofunctional glycidyl ether is 5 mass % or more, the swelling rate of the adhesive or rubber material used in the head part of the inkjet device with respect to the sealant is likely to decrease. On the other hand, if it is 50 mass % or less, the dielectric constant of the hardened material will tend to become low. Relative to the total mass of the sealant, the content of (C) monofunctional glycidyl ether is more preferably 10 mass% to 40 mass%, and further preferably 15 mass% to 30 mass%.

·(D) Cationic polymerization initiator The sealant may further contain (D) a cationic polymerization initiator. (D) The cationic polymerization initiator may be a photocationic polymerization initiator that generates an acid that can start cationic polymerization by irradiation with light such as ultraviolet rays, or a thermal cationic polymerization initiator that generates an acid by heating. . The sealant may contain only a photocationic polymerization initiator, only a thermal cationic polymerization initiator, or both. In addition, the sealing agent may contain only one type of (D) cationic polymerization initiator, or may contain two or more types. Among them, it is preferable to reduce damage to the element due to heating, that is, to harden the sealant with light, and it is preferable to include one or more photocationic polymerization initiators.

Examples of photocationic polymerization initiators include: BF ₄ ^- as an anionic part, (R _f ) _n PF _6-n (R _f is an organic group, n is an integer from 1 to 5), PF ₆ ^- , SbF ₆ ^- , Or BX ₄ ^- (X is a phenyl group substituted by at least two fluorine or trifluoromethyl groups), aromatic sulfonium salt, aromatic iodonium salt, aromatic diazonium salt, aromatic ammonium salt, etc.

Examples of aromatic sulfonium salts include: bis[4-(diphenylsonium)phenyl]sulfide bishexafluorophosphate, bis[4-(diphenylsonium)phenyl]sulfide bishexafluoroantimony acid salt, bis[4-(diphenylsonyl)phenyl]sulfide bistetrafluoroborate, bis[4-(diphenylsonyl)phenyl]sulfide tetrakis(pentafluorophenyl)borate , diphenyl-4-(phenylthio)phenylsulfonium hexafluorophosphate, diphenyl-4-(phenylthio)phenylsulfonium hexafluoroantimonate, diphenyl-4-(phenylthio) ) phenylsonium tetrafluoroborate, etc.

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

Examples of aromatic diazonium salts include: phenyldiazonium hexafluorophosphate, phenyldiazonium hexafluoroantimonate, phenyldiazonium tetrafluoroborate, phenyldiazonium tetrafluoroantimonate phenyl) borate, etc.

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

Examples of commercially available 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, preferred are Irgacure 270, Irgacure 290, CPI-100P, CPI-101A, CPI-200K, CPI-210S, CPI-310B, CPI-400PG, SP-150, SP -170, SP-171, SP-056, SP-066, SP-601, SP-606, SP-701 and other sulfur salts.

The amount of (D) cationic polymerization initiator is preferably 0.1% by mass to 10% by mass relative to the mass of the entire sealant. When the amount of the (D) cationic polymerization initiator is 0.1% by mass or more, the curability of the sealant is easily improved, and when it is 10% by mass or less, the coloring of the cured product of the sealant is easily suppressed. The amount of (D) the cationic polymerization initiator is more preferably 0.1% by mass to 5% by mass, and further preferably 0.1% by mass to 3% by mass relative to the mass of the entire sealant.

·(E) Other ingredients The sealant of the present invention may further contain components other than those described above within a range that does not impair the effects of the present invention. Examples of other ingredients include aromatic epoxy compounds, sensitizers, silane coupling agents, leveling agents, and the like.

Examples of aromatic epoxy compounds include glycidyl ethers of aromatic ring-containing alcohols (including polyhydric alcohols). 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 epoxy resin Oxygen resin, diphenyl ether type epoxy resin, naphthalene type epoxy resin, phenol novolak type epoxy resin, o-cresol novolac type epoxy resin, diphenyl novolak type epoxy resin, naphthol novolac type epoxy resin type epoxy resin, etc. The sealant may contain only one aromatic epoxy compound or two or more.

The oxygen atom content or weight average molecular weight of the aromatic epoxy compound is not particularly limited. From the viewpoint of the volatility of the compound or the reduction of the dielectric constant of the cured product of the sealant, the formula (1) represents The oxygen atom content is preferably 10% or more and 30% or less, and the weight average molecular weight is preferably 100 or more.

Among them, if the sealant contains a large amount of bisphenol A-type epoxy resin or bisphenol F-type epoxy resin, its viscosity is likely to increase. In addition, if the sealant contains a large amount of aromatic epoxy resin, the cured product of the sealant will be easily colored. Therefore, the content of the aromatic epoxy resin is preferably adjusted to a level that has little effect on the viscosity of the sealant or the coloring of the cured product.

The sensitizer has the function of further improving the polymerization start efficiency of the (D) cationic polymerization initiator and further promoting 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, Benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoyl benzoate, 4,4'-bis(dimethylamino)benzophenone, 4-benzoyl benzoate -4'-methyldiphenyl sulfide, 9,10-dibutoxyanthracene, etc. The sealant may contain only one sensitizer or two or more sensitizers.

Silane coupling agent improves the adhesion between the sealant and the object to be sealed. The silane coupling agent can be a silane compound having a reactive group such as an epoxy group, a carboxyl group, a methacryl group, or an isocyanate group. Examples of such silane compounds include: trimethoxysilyl benzoic acid, γ-methacryloxypropyltrimethoxysilane, vinyltriethyloxysilane, vinyltrimethoxysilane, γ-isopropyltrimethoxysilane Cyanatopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. The sealant may contain only one type of silane coupling agent, or may contain two or more types.

Leveling agents improve the flatness of the sealant film. 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 (both manufactured by BYK Chemie Japan), Surflon S-611 (AGC Seimi Chemical) Co., Ltd.), etc. The sealant may contain only one leveling agent or two or more.

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

·Physical properties of sealant (viscosity) The viscosity of the sealant measured at 25°C and 20 rpm using an E-type viscometer is preferably 8 mPa·s to 40 mPa·s, more preferably 10 mPa·s to 30 mPa·s, and even more preferably 11 mPa·s. s～28 mPa·s, the best is 11 mPa·s～25 mPa·s. If the viscosity of the sealant is within the above range, the sealant can be easily ejected from the inkjet device. In addition, it does not wet and expand excessively after coating, and it is easy to form a hardened material (sealing layer) of the required thickness.

(Swelling rate of EPDM B) The swelling rate of ethylene-propylene-diene rubber (EPDM) with respect to the sealant (hereinafter also referred to as EPDM swelling rate B) is preferably 10.0% or less, more preferably 9.5% or less, and still more preferably 9.0% or less. If the EPDM swelling ratio B is within the above range, even if the sealant is applied using an inkjet device for a long period of time, damage to EPDM-containing parts such as the head can be suppressed.

The EPDM swelling rate is a value measured by the following method. Prepare an ethylene-propylene-diene rubber (EPDM; "faucet gasket 9074" manufactured by Kakudai Co., Ltd.) test piece with a weight of 0.56 g (W ₁ ), and put 20 mL of In a brown screw-top tube, add 10 g of sealant and immerse the EPDM test piece. Cap the screw-top tube and place it at 40°C for one week. Thereafter, the EPDM test piece was taken out from the sealant and washed with isopropyl alcohol (IPA). Then, the surface was wiped with a rag, and then the weight (W ₂ ) was measured. Based on the following formula, the EPDM swelling rate B is calculated from the weight change of the EPDM test piece after being immersed in the sealant. EPDM swelling rate B=(W ₂ -W ₁ )/W ₁ ×100

(Dielectric constant) The frequency of the cured product obtained by curing the sealant using UV-LED with a wavelength of 395 nm at an illumination intensity of 1000 mW/cm ² and a cumulative light intensity of 1500 mJ/cm ² and then thermally curing it at 100°C for 30 minutes. The dielectric constant at 100 kHz is 3.10 or less, preferably 3.00 or less, more preferably 2.90 or less, still more preferably 2.80 or less. If the dielectric constant of the hardened material is 3.0 or less, when a display element, for example, is sealed with the hardened material (sealing layer), the insulation of the hardened material is sufficiently high to prevent the display element from interfering with other components (for example, a sensor). etc.) interference. The dielectric constant can be measured using the LCR meter HP4284A (manufactured by Agilent Technologies) and the automatic balancing bridge method.

The dielectric constant of the hardened material of the sealant can be adjusted by the oxygen content of the entire sealant. The oxygen content is preferably 30% or less, more preferably 25% or less, still more preferably 20% or less. The oxygen atom content rate of the entire sealant can be calculated as (total mass of oxygen atoms contained in the sealant/total mass of the sealant) × 100 (%). The total mass of oxygen atoms contained in the sealant can be calculated by calculating the content ratio of oxygen atoms by elemental analysis and multiplying this by the atomic weight of oxygen atoms.

(light transmittance) Regarding the light transmittance of the cured product of the sealant when the thickness is 10 μm, the average light transmittance at a wavelength of 380 nm to 800 nm is preferably 85% or more, more preferably 90% or more. When the light transmittance of the cured product of the sealing agent is within the above range, it has good light transmittance and is therefore suitable as a surface sealing agent for organic EL elements, for example. The average light transmittance can be measured, for example, using a UV-visible spectrophotometer (manufactured by SHIMADZU Corporation) as the average value of the light transmittance measured per wavelength of 1 nm in the wavelength range of 380 nm to 800 nm.

·Preparation method of sealant The sealant can be obtained by mixing the above ingredients using, for example, a mixer such as a homodisperser, a homomixer, a universal mixer, a planetary mixer, a kneader, and a three-roller. Furthermore, from the viewpoint of stably mixing the sealant, it is more preferred to mix the (D) cationic polymerization initiator after mixing the components other than the (D) cationic polymerization initiator.

·Use of sealant The sealant is suitable for sealing various elements such as organic EL elements, LED elements, semiconductor elements, and solar cell elements. However, its use is not limited to surface sealing of elements, but may also be used as a liquid crystal sealing compound for a liquid crystal display device. In addition, in particular, since it has excellent light transmittance, it is suitable as a surface sealant for display elements.

2. Manufacturing methods of various devices Hereinafter, methods of manufacturing various devices for surface sealing various components using the sealant will be described. However, the method of manufacturing a device using the sealant is not limited to this method. The manufacturing method of various devices only needs to include the steps of 1) preparing the component and 2) applying the sealant on the component and sealing the component, and may also include other steps.

1) In step 1, prepare the components. Components are usually arranged on a substrate. The substrate may be a glass substrate or a resin substrate. When obtaining a flexible display device, a resin substrate (resin film) is preferred.

In addition, the type of the element is not particularly limited and may be a semiconductor element or the like. Preferably, it is an element that converts electricity into light or light into electricity. Examples of such elements include organic EL elements, LED elements, solar cell elements, and the like. Among them, the element is preferably an organic EL element. When the element is an organic EL element, the organic EL element usually includes a reflective pixel electrode layer, an organic EL layer, and a transparent counter electrode layer. Furthermore, the organic EL element may further include other functional layers if necessary.

In step 2), the sealant is applied using an inkjet method so as to cover the components arranged on the substrate. By applying the sealant using an inkjet method, a coating film with high flatness and thin thickness can be formed at high speed.

Thereafter, the sealant applied on the element is cured to obtain a cured material layer. The sealant is preferably cured by light. For light hardening, known light sources such as xenon lamps and carbon arc lamps can be used. In addition, the irradiation dose is not particularly limited as long as the sealant can be sufficiently hardened. For example, light with a wavelength of 300 nm to 400 nm can be irradiated with a cumulative light dose of 300 mJ/m ² to 3000 mJ/m ² .

In addition, by performing thermal hardening after photohardening, the dielectric constant of the hardened product can be further reduced. Regarding thermal hardening performed after photohardening, from the viewpoint of further improving the curability without causing damage to the element, the heating temperature is preferably set to about 50°C to 120°C, and the heating time is preferably set to 1 minute to 1 hour.

The thickness of the hardened material layer (sealing layer) of the sealant is sufficient as long as the element can be fully sealed and a film with high flatness can be formed. For example, 1 μm to 20 μm is preferred, and 3 μm is more preferred. ~10 μm. [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.

1. Material of sealant (A) Alicyclic epoxy compound having two or more ethylhexyl groups ·Sansocizer E-PS (manufactured by Shin Nippon Rika Co., Ltd., epoxy hexahydrophthalate di-2-ethylhexyl represented by the following formula, molecular weight: 410)

[Chemistry 5]

(B) Multifunctional oxetane compounds ·OXT-221 (manufactured by Toagosei Co., Ltd., Arone Oxetane) OXT-221 (3-ethyl-3{[(3-ethyloxetane represented by the following formula Alk-3-yl)methoxy]methyl}oxetane))

[Chemical 6]

(C) Monofunctional glycidyl ether ·m,p-CGE (manufactured by Sakamoto Pharmaceutical Co., Ltd., m-p-cresol-based glycidyl ether, epoxy equivalent 165 g/eq, viscosity: 7 mPa·s, EPDM swelling rate A: 4.3%) ·ED-509S (manufactured by ADEKA Co., Ltd., p-tert-butylphenyl glycidyl ether, epoxy equivalent 206 g/eq, viscosity: 20 mPa·s, EPDM swelling rate A: 1.2%) In addition, the EPDM swelling rate A is a value measured in the same manner as the EPDM swelling rate B described below, except that (C) monofunctional glycidyl ether is used instead of the sealant and the evaluation temperature is 25°C. value.

·(D) Cationic polymerization initiator·CPI-210S (diphenyl-4-(phenylsulfanyl)phenylsonium hexafluorophosphate represented by the following formula manufactured by San-Apro Co., Ltd.) [ chemical 7] X ^- : (R _f ) _n PF _6-n ^- (R _f is an organic group, n is an integer from 1 to 5)

(E) Sensitizer UVS-1331 (Anthracure UVS-1331 (9,10-dibutoxyanthracene represented by the following formula) manufactured by Kawasaki Chemical Industry Co., Ltd.) [Chemical 8]

(F) Epoxidized fatty acid ester ·D-32: (manufactured by ADEKA Co., Ltd., Adekaiza D-32 (epoxidized fatty acid octyl ester), viscosity: 52 mPa·s) ·D-55: (manufactured by ADEKA Co., Ltd., Adekaiza D-55 (epoxidized fatty acid alkyl ester), viscosity: 20 mPa·s)

2. Preparation of sealant (A) an alicyclic epoxy compound having two or more ethylhexyl groups, (B) a polyfunctional oxetane compound, and (C) a monofunctional glycidyl compound so as to have the composition shown in Table 1. Ether, (E) sensitizer, and (F) epoxidized fatty acid ester are put into a flask and mixed. The cationic polymerization initiator (D) in the amount shown in Table 1 was added to the obtained mixture and further mixed. Thereafter, the mixture is stirred until powdery matter is no longer visible, thereby obtaining a sealant. In addition, the unit related to the composition of each component shown in Table 1 is a mass part.

3. Evaluation The viscosity, EPDM swelling ratio B, and dielectric constant of the obtained sealant were evaluated as follows.

[viscosity] The viscosity of the obtained sealant was measured at 25°C and 20 rpm using an E-type viscometer (LV-DV-II+ manufactured by BROOKFIELD). In addition, evaluation was performed as follows depending on the situation during or after application of the sealant. 〇: Coating can be performed stably from an inkjet device, and a hardened product of the required thickness can be produced. ×: Mist is generated when inkjet is ejected

[EPDM Swelling Rate B] Prepare an ethylene-propylene-diene rubber (EPDM) test piece with a weight of 0.5 g (W ₁ ), place it in a screw-top tube, add the obtained sealant thereto, and immerse the EPDM test piece. Cap the screw-top tube and place it at 40°C for one week. Thereafter, the EPDM test piece was taken out from the sealant, its surface was wiped with a rag, and then the weight (W ₂ ) was measured. Based on the following formula, the EPDM swelling rate B is calculated from the weight change of the EPDM test piece after being immersed in the sealant. EPDM swelling rate B=(W ₂ -W ₁ )/W ₁ ×100 Furthermore, the EPDM swelling rate was evaluated based on the following criteria. 〇: EPDM swelling rate ≦10% ×: EPDM swelling rate > 10%

[Dielectric constant] The obtained sealant was introduced into an inkjet cartridge DMC-11610 (manufactured by Fuji Film Dimatix). The inkjet cartridge was installed in an inkjet device DMP-2831 (manufactured by Fuji Film Dimatix), the ejection state was adjusted, and then the inkjet cartridge was printed on alkali-free glass with a thickness of 100 nm. On a substrate made of vapor-deposited aluminum, the coating is applied in a size of 5 cm × 5 cm so that the thickness after hardening is 10 μm. The obtained coating film was left at room temperature (25°C) for 1 minute, and then hardened using UV-LED with a wavelength of 395 nm at an illumination intensity of 1000 mW/cm ² and a cumulative light amount of 1500 mJ/cm ² . The obtained cured product was designated as a "UV-cured only" cured product. Next, the cured product of "UV curing only" was thermally cured at 100°C for 30 minutes. The obtained hardened product was designated as a "UV cured + thermal hardened" cured product. For each cured product obtained, aluminum was evaporated to a thickness of 100 nm on the inkjet coating surface, and an LCR meter HP4284A (Agilent Technologies) was used. (manufactured by Agilent Technologies) and the dielectric constant was measured using the automatic balanced bridge method at a condition of 100 kHz. Furthermore, the dielectric constant was evaluated based on the following standards. 〇: Dielectric constant ≦3.10 ×: Dielectric constant > 3.10

[Table 1]

As shown in Table 1, Example 1 containing (A) an alicyclic epoxy compound having two or more ethylhexyl groups, (B) a polyfunctional oxetane compound, and (C) a monofunctional glycidyl ether Regardless of the type of the (C) monofunctional glycidyl ether, the sealant of Example 2 was evaluated favorably in terms of viscosity and EPDM swelling ratio B. Furthermore, the dielectric constant of the UV-cured sealant was also good at 3.10 or less. In addition, by performing thermal curing after UV curing, the dielectric constant can be further reduced.

On the other hand, a comparative example containing (A) an alicyclic epoxy compound having two or more ethylhexyl groups but not containing (B) a polyfunctional oxetane compound and (C) a monofunctional glycidyl ether The viscosity of the sealant in 1 is very high, exceeding 40.0 mPa·s, and cannot be applied with an inkjet device.

In addition, Comparative Example 2 which contains (B) a polyfunctional oxetane compound but does not contain (A) an alicyclic epoxy compound having two or more ethylhexyl groups and (C) a monofunctional glycidyl ether The viscosity of the sealant is good in the range of 8 mPa·s or more and 40 mPa·s or less, but the EPDM swelling rate B exceeds 10% and is high.

Furthermore, Comparative Example 3 which contains (A) an alicyclic epoxy compound having two or more ethylhexyl groups and (B) a polyfunctional oxetane compound but does not contain (C) a monofunctional glycidyl ether The viscosity of the sealant is good in the range of 8 mPa·s or more and 40 mPa·s or less, but the EPDM swelling rate B exceeds 10% and is high. Similarly, (B) a polyfunctional oxetane compound and (F) an epoxidized fatty acid ester are included instead of (A) an alicyclic epoxy compound having two or more ethylhexyl groups and (C) The viscosity of the sealants of Comparative Examples 4 and 5 of the monofunctional glycidyl ether is in the range of 8 mPa·s or more and 40 mPa·s or less, which is good, but the EPDM swelling rate B exceeds 10% and is high.

This application claims priority based on Japanese Patent Application No. 2018-163001, which was filed on August 31, 2018. All contents described in the application specification are incorporated into this application specification. [Industrial availability]

The sealant of the present invention can suppress damage to the inkjet head of an inkjet device, and therefore can be applied stably over a long period of time by the inkjet method. In addition, the dielectric constant of the cured product of the sealant is also low. Therefore, when the sealant is used to seal a display element, the display element can be placed close to a sensor, etc., and a thin display device or design can be produced. A display device with a high degree of freedom.

without

without

Claims (10)

A sealant containing: (A) an alicyclic epoxy compound having two or more ethylhexyl groups, (B) a multifunctional oxetane compound, and (C) a monofunctional glycidyl ether, wherein relative to The total mass of the sealant, the amount of the (A) alicyclic epoxy compound having two or more ethylhexyl groups is 10% to 50% by mass, and the (B) multifunctional oxetane compound The amount is 20 mass% to 80 mass%, the (C) monofunctional glycidyl ether is 5 mass% to 50 mass%, and an ultraviolet light-emitting diode lamp with a wavelength of 395nm is used for the sealant. The cured product obtained by ultraviolet curing under the conditions of illumination intensity: 1000mW/cm ² and cumulative light intensity: 1500mJ/cm ² and then heat curing at 100°C for 30 minutes has a dielectric constant of 3.10 or less at a frequency of 100kHz. For the sealant described in item 1 of the patent application, the viscosity measured using an E-type viscometer under the conditions of 25°C and 20rpm is 8mPa. s~40mPa. s. The sealant described in claim 1, wherein (A) the alicyclic epoxy compound having two or more ethylhexyl groups is an epoxy hexahydro-phthalate represented by the following formula (I) Di-2-ethylhexyl dicarboxylate,

The sealant described in item 1 of the patent application, wherein the (C) monofunctional glycidyl ether is a phenyl glycidyl ether derivative. The sealant described in claim 1, wherein an ethylene-propylene-diene rubber test piece is immersed in the (C) monofunctional glycidyl ether for one week at 25°C. The swelling rate A of the ethylene-propylene-diene rubber represented by the weight change rate before and after immersion is 5% or less. For the sealant described in item 1 of the patent application, the viscosity of the (C) monofunctional glycidyl ether measured using an E-type viscometer at 25°C and 20 rpm is 35 mPa. s or less. The sealant described in claim 1, wherein an ethylene-propylene-diene rubber test piece is immersed in the sealant for one week at 40° C. and the weight change rate of the test piece before and after immersion. The indicated swelling ratio B of the ethylene-propylene-diene rubber is 10% or less. The sealant described in item 1 of the patent application is used for display components. The sealant described in Item 1 of the patent application is used for coating by the inkjet method. The sealant described in item 8 of the patent application, wherein the display element is an organic electroluminescent element.