JP2005187636A - Photo-curable resin composition, adhesive for display device, method of bonding and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo-curable resin composition which has low moisture permeability, makes a highly transparent cured product and helps achieve an extended service life of a display device effectively, for instance, when used as an adhesive (sealant) for the display device, an adhesive for a display device using the photo-curable resin composition, a method of bonding using the adhesive for a display device and a display device using the adhesive for a display device and/or the method of bonding. <P>SOLUTION: The photo-curable resin composition contains a photo-cationically polymerizable compound and a photo-cationic polymerization initiator, gives a cured product having a total light transmission of ≥80% for the light with wavelength of 380-780 nm as determined by spectrophotometry and a glass transition temperature of ≥85°C. The adhesive for a display device using the photo-curable resin composition, the method of bonding using the adhesive for a display device and the display device using the adhesive for a display device and/or the method of bonding are presented. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a photocurable resin composition, an adhesive for a display element using the same, a bonding method using the same, and a display element using the adhesive for a display element or the bonding method.

  Among display elements such as electroluminescence elements (hereinafter sometimes referred to as “EL elements”) and liquid crystal display elements, organic electroluminescence elements (hereinafter sometimes referred to as “organic EL elements”) are self-luminous. Therefore, it has an advantage of a wide viewing angle and a thin shape, and has attracted attention as a next-generation display, but generally has a problem that its life is short. One of the causes of the short lifetime (low lifetime) of the organic EL element is that the organic EL element has a defect that it is easily deteriorated rapidly by moisture (humidity). Therefore, it is desirable to always keep the organic EL element in an absolutely dry state.

  For this reason, in general, an organic EL element is covered with a glass or metal lid in which a desiccant is placed on the organic EL element, and the periphery thereof is sealed with an adhesive (sealing agent). Yes. In this case, in the space where the organic EL element exists, the upper and lower sides are covered with glass or metal, so that it is considered that there is almost no ingress of moisture, but the side surface (periphery) is photo-curing or thermosetting bonding. Since it is sealed with a cured product of the agent, intrusion of moisture from this portion becomes a problem. Therefore, it is extremely important to reduce the moisture permeability (moisture permeability) of the cured adhesive itself used for the sealing.

  On the other hand, in recent years, a top emission type organic EL element has attracted attention in place of the conventional peripheral sealing type organic EL element. This method is different from the conventional method (bottom emission method) in the direction in which light is extracted. However, this method has the advantage that it has a high aperture ratio and low voltage driving, which is advantageous for extending the life. is there.

  In the case of the top emission method, generally, a structure in which the upper and lower sides of the organic EL element are sealed with a flat glass substrate and a sealing material is sandwiched between the gaps is adopted. Therefore, the sealing material used in this method is strongly required not only to have low moisture permeability but also to have excellent transparency.

  As a method for reducing the moisture permeability of the sealing material for organic EL elements, for example, a large amount of inorganic filler such as silica having an average particle size of several μm is added (added) in a photocurable or thermosetting resin. The way to be done. However, since the sealing material containing a large amount of inorganic filler is impaired in transparency, it cannot be applied to applications requiring excellent transparency as in the case of the top emission method. There is. In addition, a sealing material containing as little inorganic filler as possible or a sealing material not containing an inorganic filler does not have a sufficiently low moisture permeability and contains, for example, a polymerization initiator (curing agent) containing iodine (I). ) Or the like, there is a problem that coloring such as yellowing occurs in the curing process.

  In view of the above problems, an object of the present invention is a cured product having low moisture permeability and excellent transparency, for example, when used as an adhesive (sealing agent) for a display element. Photocurable resin composition capable of effectively achieving a long life of the display, an adhesive for display elements using the photocurable resin composition, and adhesion using the adhesive for display elements It is an object of the present invention to provide a method and a display element using the adhesive for a display element and / or the bonding method.

  The photocurable resin composition according to the invention of the present invention (the present invention) comprises a photocationically polymerizable compound and a photocationic polymerization initiator, and the cured product has a wavelength of 380 to 380 in a spectrophotometer. The total light transmittance of light of 780 nm is 80% or more, and the glass transition temperature is 85 ° C. or more.

The photocurable resin composition according to the invention described in claim 2 is the photocurable resin composition according to claim 1, wherein the cured product is a condition of 85 ° C.-85% RH in accordance with JIS Z 0208. The moisture permeability measured below is 150 (g / m ² · 24 h / 100 μm) or less.

  The photocurable resin composition according to the invention of claim 3 is the photocurable resin composition of claim 1 or 2, wherein the photocationic polymerization initiator absorbs light having a wavelength of 300 to 380 nm. It is a sulfonium salt.

The photocurable resin composition according to the invention described in claim 4 is the photocurable resin composition according to any one of claims 1 to 3, wherein the photocationic polymerization initiator is represented by the following formula (1). It is a borate salt having a boronic acid represented by the above formula as a counter anion.

  The photocurable resin composition according to the invention described in claim 5 is the photocurable resin composition according to any one of claims 1 to 4, based on 100 parts by weight of the photocationically polymerizable compound. Further, 0.1 to 20 parts by weight of a curing control agent is blended.

  The adhesive for display elements according to the invention described in claim 6 (the present invention) is characterized by using the photocurable resin composition described in any one of claims 1 to 5. .

  A bonding method according to the invention described in claim 7 (the present invention) is a method of bonding display elements using the adhesive for display elements according to claim 6, wherein light is applied to the adhesive for display elements. After the irradiation, the adherends are bonded and bonded together until the display element adhesive is cured.

  The bonding method according to an eighth aspect of the present invention is the bonding method according to the seventh aspect, wherein the adhesive for a display element according to the sixth aspect is applied to at least one adherend, and the bonding for the display element is performed. After irradiating light to the agent, the other adherend is bonded and further cured at a temperature of 80 ° C. or lower to cure the display element adhesive, or the display element adhesive according to claim 6. After irradiating the agent with light, this display element adhesive is applied to at least one adherend, the other adherend is bonded together, and further post-cured at a temperature of 80 ° C. or lower to display element adhesive. The display element adhesive according to claim 6 is irradiated with light, and then the display element adhesive is filled between both adherends and further heated at a temperature of 80 ° C. or lower. Curing is performed to cure the adhesive for display elements.

  A display element according to the invention of the ninth aspect (the present invention) is produced using the adhesive for a display element according to the sixth aspect and / or according to the seventh or eighth aspect. It is produced by an adhesion method.

  The cured product of the photocurable resin composition of the present invention needs to have a total light transmittance of 80% or more for light having a wavelength of 380 to 780 nm in a spectrophotometer.

  When the total light transmittance of the cured product of the photocurable resin composition is less than 80%, the transparency of the cured product becomes insufficient. For example, a display element is produced using the photocurable resin composition. When it does, the optical characteristic of the display element obtained becomes inadequate.

  In addition, as the spectrophotometer, for example, a trade name “COLOR ANALYZER TC-1800M” manufactured by Tokyo Denshoku Co., Ltd. can be used. The total light transmittance can be determined by applying a defoamed photocurable resin composition to a thickness of 100 μm using, for example, a Baker type applicator, and irradiating a predetermined amount of light at room temperature for 1 hour. After being allowed to stand, the coating film for measurement prepared by heating and curing at 80 ° C. for 30 minutes can be measured using, for example, a trade name “AUTOMATIC HAZE METER MODEL TC-IIIDPK” manufactured by Tokyo Denshoku Co., Ltd.

  Moreover, the cured product of the photocurable resin composition of the present invention needs to have a glass transition temperature of 85 ° C. or higher.

  When the glass transition temperature of the cured product of the photocurable resin composition is less than 85 ° C., the moisture permeability of the cured product is increased, and for example, when a display element is produced using this photocurable resin composition, It becomes difficult to achieve a long lifetime of the display element obtained.

  The glass transition temperature is a dynamic viscoelasticity at a heating rate of 10 ° C./min for a measurement coating film prepared in the same manner as in the measurement of the total light transmittance. The measurement can be performed by determining the peak value of tan δ.

Furthermore, the cured product of the photocurable resin composition of the present invention has a permeability measured at 85 ° C. to 85% RH in accordance with JIS Z 0208 “Moisture permeability test method for moisture-proof packaging materials (cup method)”. The humidity is preferably 150 (g / m ² · 24 h / 100 μm) or less.

When the moisture permeability of the cured product of the photocurable resin composition exceeds 150 (g / m ² · 24 h / 100 μm), it can be obtained, for example, when a display element is produced using the photocurable resin composition. It may be difficult to achieve a long lifetime of the display element.

  The photocurable resin composition of the present invention contains a photocationically polymerizable compound and a photocationic polymerization initiator.

  The photocationically polymerizable compound used in the photocurable resin composition of the present invention is not particularly limited as long as it is a compound having at least one photocationically polymerizable functional group in the molecule. Examples include compounds having a photocationically polymerizable functional group such as at least one epoxy group, oxetanyl group, hydroxyl group, vinyl ether group, episulfide group, and ethyleneimine group in the molecule. A compound having at least one epoxy group in the molecule (hereinafter referred to as “epoxy compound”) is suitably used because photocuring proceeds efficiently even with a small amount of light. The properties (molecular weight) of these photocationically polymerizable compounds are not particularly limited, and any of monomers, oligomers, and polymers may be used. Moreover, these photocationic polymerizable compounds may be used independently and 2 or more types may be used together.

  The epoxy compound is not particularly limited, and examples thereof include bisphenol A type epoxy resins, bisphenol F type epoxy resins and other bisphenol type epoxy resins, phenol novolak type epoxy resins, and cresol novolak type epoxy resins. Type epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, multifunctional epoxy resin, biphenyl type epoxy resin, glycidyl ether type epoxy resin, glycidyl ester type epoxy resin, glycidyl amine type epoxy resin Alcohol type epoxy resins such as hydrogenated bisphenol A type epoxy resins, halogenated epoxy resins such as brominated epoxy resins, rubber modified epoxy resins, urethane modified epoxy resins, epoxidized polymers Butadiene, epoxidized styrene - butadiene - styrene block copolymer, epoxy group-containing polyester resin, epoxy group-containing polyurethane resins, epoxy group-containing acrylic resins. These epoxy compounds may be used alone or in combination of two or more.

  Although it does not specifically limit as a commercial item of the said epoxy-type compound, For example, brand name "Epicoat 806", "Epicoat 828", "Epicoat 1001", "Epicoat 1002" by Japan Epoxy Resin Co., Ltd. etc. “Epicoat” series, “Celoxide” series such as “Celoxide 2021” manufactured by Daicel Chemical Industries, Ltd.

  In the photocurable resin composition of the present invention, a photocationically polymerizable compound exemplified above, preferably a photocationically polymerizable compound other than the epoxy compound exemplified above may be used.

  The other photocationically polymerizable compound is not particularly limited, and examples thereof include epoxides, cyclic ethers, vinyl ethers, vinylamines, unsaturated hydrocarbons, lactones, and other cyclic esters. At least one photocationic polymerization such as lactams, cyclic carbonates, cyclic acetals, aldehydes, cyclic amines, cyclic sulfides, cyclosiloxanes, cyclotriphosphazenes and other photocationically polymerizable groups and monomers Examples thereof include photocationically polymerizable compounds having a possible group, and among them, cyclic ether monomers such as epoxide monomers, vinyl organic monomers, and the like are preferably used. These other photocationically polymerizable compounds may be used alone or in combination of two or more.

  In the photocurable resin composition of this invention, when using the said epoxy-type compound as a photocationic polymerizable compound, it is preferable that the epoxy conversion rate of hardened | cured material is 85% or more.

  When the epoxy conversion rate of the cured product of the photocurable resin composition using an epoxy compound as the photocationically polymerizable compound is less than 85%, the photocurable resin composition is not sufficiently cured, and the cured product is cured. The glass transition temperature may not be 85 ° C. or higher, moisture permeability may be increased, and mechanical properties such as mechanical strength may be insufficient.

  The epoxy conversion rate was determined by cutting a measurement coating film prepared in the same manner as in the measurement of the total light transmittance into a predetermined size, immersing in ethyl acetate and allowing to stand overnight. The amount of epoxy groups eluted in ethyl can be measured by titrating with a hydrochloric acid / dioxane mixture.

  The photocationic polymerization initiator used in the photocurable resin composition of the present invention is not particularly limited as long as it can be activated (excited) by being irradiated with light to cure the photocationically polymerizable compound. Although not particularly limited, for example, light having a sulfonium cation moiety represented by the following general formula (2) or the following general formula (3) and a boron center anion moiety represented by the following general formula (4) Examples thereof include a cationic polymerization initiator (A), an ionic photoacid-generating photocationic polymerization initiator (B), and a nonionic photoacid-generating photocationic polymerization initiator (C). Initiator (A) is preferably used. These cationic photopolymerization initiators may be used alone or in combination of two or more.

In the above general formula (2) and general formula (3), R ^{1 to} R ⁶ may be the same or different from each other, and each represents a monovalent or divalent phenyl group or naphthyl group, these phenyl or naphthyl group, linear or branched C ₁ -C ₁₂ alkyl group, linear or branched C ₁ -C ₁₂ alkoxyl group, a halogen atom, -OH group, -COOH group And a —COO-alkyl ester group (wherein the alkyl moiety is a linear or branched C ₁ -C ₁₂ residue) optionally substituted with one or more groups. .

In the general formula (4), B represents trivalent boron, and at least one of R ^{1 to} R ⁴ represents a halogen-substituted aromatic group having 6 to 30 carbon atoms. When the central anion is boron as described above, the acid strength of the photocationic polymerization initiator (A) is increased, and the curability of the photocurable resin composition using the photocationic polymerization initiator (A) is improved. In addition, a cured product having a high glass transition temperature can be obtained. As a result, the moisture permeability of the cured product of the photocurable resin composition is lowered, so that the lifetime of, for example, a display element manufactured using the photocurable resin composition can be increased, and the reliability can be improved. it can.

In the general formula (4), at least one of R ^{1 to} R ⁴ is a halogen-substituted aromatic group having 6 to 30 carbon atoms. Although it does not specifically limit as said aromatic group, For example, a phenyl group, a naphthyl group, an anthracenyl group etc. are mentioned. In addition, the halogen substituent is not particularly limited, and examples thereof include chlorine, fluorine, and the like. Among them, fluorine is preferably used. The halogen substituent may be a halogen group directly bonded to the aromatic ring of the aromatic group, or it is introduced as a part of another substituent as in the case of a halo-hydrocarbyl substituent. There may be a fluoro-hydrocarbyl substituent among them.

In the photocationic polymerization initiator (A), useful boron center anions are not particularly limited, and examples thereof include [3,5- (CF ₃ ) ₂ C ₆ H ₃ ] ₄ B ⁻ , ( ^{_{C 6 F 5) 4 B -}} , (C 6 H 4 -p-CF 3) 4 B -, (C 6 H 4 -m-CF 3) 4 B -, (C 6 H 4 -p-F) 4 ^{_{B -, (C 6 F 5}} ) 3 (CH 3) B -, (C 6 F 5) 3 (n-C 4 H 9) B -, (C 6 H 4 -p-CH 3) 3 (C 6 ^{_{F 5) B -, (C}} 6 F 5) 3 FB -, (C 6 H 5) 3 (C 6 F 5) B -, (CH 3) 2 (C 6 H 4 -p-CF 3) 2 B ^{_{-, (C 6 F 5)}} 3 (n-C 18 H 37 O) B - , and the like.

The preferred boron center anion generally contains three or more halogen-substituted aromatic groups bonded to boron, and the halogen substituent is most preferably fluorine. Examples of the most preferred boron center anion are not particularly limited, and examples thereof include [3,5- (CF ₃ ) ₂ C ₆ H ₃ ] ₄ B ⁻ , (C ₆ F ₅ ) ₄ B ⁻ , _{(C 6 F 5) 3 (} CH 3) B -, (C 6 F 5) 3 (n-C 4 H 9) B -, (C 6 F 5) 3 FB - , and the like.

In addition, suitable anions containing other useful metal centers or metalloid centers can also be used, and examples of such anions include, but are not limited to, [3,5- (CF ₃ ) ₂ C ₆ H ₃ ] ₄ Al ⁻ , (C ₆ F ₅ ) ₄ Al ⁻ , (C ₆ F ₅ ) ₂ F ₄ P ⁻ , (C ₆ F ₅ ) F ₅ Sb ⁻ , (C ₆ F ₅ ) F ₅ P- ^{and the} like can be mentioned. In addition, other boron-centered non-nucleophilic salts that may be useful, other useful anions containing other metals and metalloids, and the like can be used.

  The photocationic polymerization initiator (A) has light absorption derived from the cation moiety (cationic structure) represented by the general formula (2) or the general formula (3) in light having a wavelength of 300 nm or more. Even when using ordinary light using a high-pressure mercury lamp or an ultrahigh-pressure mercury lamp as a light source, it is not always necessary to use a photosensitizer. Therefore, the photocurable resin composition using the above-mentioned photocationic polymerization initiator (A) can also prevent coloring caused by the photosensitizer itself or its reaction product.

  Further, the photocationic polymerization initiator (A) has a function of remarkably increasing the glass transition temperature of the cured product of the photocurable resin composition, unlike the phosphoric photocationic polymerization initiator and the antimony photocationic polymerization initiator. Have. Therefore, the cured product of the photocurable resin composition using the photocationic polymerization initiator (A) has a low moisture permeability, and for example, the lifetime of the display element can be maintained over a long period of time.

  Although the said photocationic polymerization initiator (A) is not specifically limited, The molecular weight of the anion part represented by the said General formula (4) is 400 or more, and absorbs light with a wavelength of 300 nm or more. It is preferable to absorb light having a wavelength of 300 to 380 nm.

  When the molecular weight of the anion moiety represented by the general formula (4) of the photocationic polymerization initiator (A) is less than 400, the molecules easily move, and this photocationic polymerization initiator (A) is used. For example, when the photocurable resin composition used is used for manufacturing a display element, electrode corrosion may occur. In addition, when the light absorption of the photocationic polymerization initiator (A) is light having a wavelength of less than 300 nm, this photocationic polymerization is initiated when normal light using a high pressure mercury lamp or an ultrahigh pressure mercury lamp as a light source is used. Curing of the photocurable resin composition using the agent (A) may be insufficient, and conversely, if the light absorption of the photocationic polymerization initiator (A) is light exceeding a wavelength of 380 nm, The photocurable resin composition using the photocationic polymerization initiator (A) may be colored in the course of curing.

  The photocationic polymerization initiator (A) has a cation moiety represented by the general formula (2) or the general formula (3) and an anion moiety represented by the general formula (4). Any photocationic polymerization initiator (A) may be used as long as the molecular weight of the anion moiety is 400 or more and light absorption is preferably light having a wavelength of 300 nm or more, more preferably light having a wavelength of 300 to 380 nm. Although it may be, among them, since it is excellent in the coloring prevention effect in the curing progress process of the photocurable resin composition using the photocationic polymerization initiator (A) and the glass transition temperature increasing effect of the cured product, The photocationic polymerization initiator (A) represented by the general formula (5) or the following general formula (6) is preferable. That is, the photocationic polymerization initiator (A) is preferably a sulfonium salt and / or a borate salt. These photocationic polymerization initiators (A) may be used alone or in combination of two or more.

In the general formula (5) and the general formula (6), X ⁻ represents a bulky boronic acid counter anion represented by the following formula (1).

  Of these photocationic polymerization initiators (A), those commercially available are not particularly limited. For example, trade name “PI” manufactured by Rhône-Poulenc represented by the following formula (7): -2074 ", Toyo Ink's trade name" TAG-371R "represented by the following formula (8), Toyo Ink trade name" TAG-372R "represented by the following formula (9), and the like. It is done.

  In general, since the photocationic polymerization initiator (A) containing iodine (I) can absorb light having a long wavelength, the polymerization (curing) initiation wavelength can be expected to be on the long wavelength side. The cured product may be colored. In this case, by using the photocationic polymerization initiator (A) represented by the following formula (10) to the following formula (12), the polymerization start wavelength is set to the long wavelength side without causing coloring of the cured product. be able to.

  The cationic photopolymerization initiator (A) is not particularly limited. For example, a sulfonium compound such as triphenylsulfonium bromide is reacted with a boron fluoride compound such as sodium tetrakis (pentafluorophenyl) borate. Can be synthesized.

  The ionic photoacid-generating photocationic polymerization initiator (B) is not particularly limited, and examples thereof include onium salts such as aromatic diazonium salts, aromatic halonium salts, and aromatic sulfonium salts, and iron. -Organometallic complexes such as allene complex, titanocene complex, and arylsilanol-aluminum complex. These ionic photoacid-generating photocationic polymerization initiators (B) may be used alone or in combination of two or more.

Specific examples of the onium salt are not particularly limited. For example, (C ₆ H ₅ ) ₂ I [B (C ₆ F ₅ ) ₄ ], (CH ₃ C ₆ H ₄ ) ₂ I [ B (C ₆ F ₅ ) ₄ ], (C ₆ H ₅ ) ₃ S [B (C ₆ F ₅ ) ₄ ], (C ₆ H ₅ ) ₃ C [B (C ₆ F ₅ ) ₄ ], (C _{6 H 5) 3 S [BF} (C 6 F 5) 3], (C 2 H 5) 3 NH [BF (C 6 F 5) 3], (C 2 H 5) OH [B (C 6 F 5 _{) 4], (C 2 H} 5) 3 NH [B (C 6 F 5) 4], (C 6 H 5) 2 I [B _{[3,5- (CF 3) 2 C 6} H 3 ] _{4] , (C 6 H 5) 3} S [B _{[3,5- (CF 3) 2 C 6} H 3 ] _{4], (C 2 H 5} ) 2 OH [B [3,5- (CF _{3) 2} C ₆ H _{3] 4], (C 6 H 5} S) C 6 H 4 S (C 6 H 5) 2 [B _{[3,5- (CF 3) 2 C 6} H 3 ] _4], (C ₂ H _{5) 3} NH [B _{3,5- (CF 3) 2 C 6} H 3 ] _{4], C 6 H 5 N} 2 [B _{[3,5- (CF 3) 2 C 6} H 3 ] _{4], (C 6 H 5} ) 3 P [BF (CH ₃ ) [B [3,5- (CF ₃ ) ₂ C ₆ H ₃ ] ₄ ], (C ₂ H ₅ ) ₃ NH [B (CH ₃ ) (C ₆ F ₅ ) ₃ ], (C ₆ H ₅ ) ₂ I [B (CH ₃ ) (C ₆ F ₅ ) ₃ ], (C ₆ H ₅ ) ₃ S [B (CH ₃ ) (C ₆ F ₅ ) ₃ ], (C ₆ H ₅ ) ₃ S [B (n-C ₄ H ₉ ) (C ₆ F ₅ ) ₃ ], C ₆ H ₅ N (CH ₃ ) ₂ H [B [3,5- (CF ₃ ) ₂ C ₆ H _{3 4} ], C ₆ H ₅ NH [B [3,5- (CF ₃ ) ₂ C ₆ H ₃ ] ₄ ], C ₆ H ₅ N (CH ₃ ) ₂ H [B (C ₆ F ₅ ) ₄ ] , C ₆ H ₅ N (CH ₃ ) ₂ H [B (CH ₃ ) (C ₆ F ₅ ) ₃ ] and the like. These onium salts may be used alone or in combination of two or more.

  Although it does not specifically limit as what is marketed among the said ionic photoacid generation type photocationic polymerization initiators (B), For example, the brand name "Adeka optomer SP150" by Asahi Denka Kogyo Co., Ltd. “Adekaoptomer” series such as “Adekaoptomer SP170”, a product name “UVE-1014” of General Electronics Co., Ltd., a product name “CD-1012” of Sartomer Company, and the like.

  Further, the nonionic photoacid-generating photocationic polymerization initiator (C) is not particularly limited, and examples thereof include nitrobenzyl esters, sulfonic acid derivatives, phosphate esters, phenol sulfonate esters, diazo compounds. Examples thereof include naphthoquinone and N-hydroxyimidophosphonate. These nonionic photoacid-generating photocationic polymerization initiators (C) may be used alone or in combination of two or more.

  Although content of the said photocationic polymerization initiator in the photocurable resin composition of this invention is not specifically limited, The said photocationic polymerization initiator 0 with respect to 100 weight part of said photocationic polymerizable compounds. It is preferable that it is 1-10 weight part.

  If the content of the photocationic polymerization initiator relative to 100 parts by weight of the photocationic polymerizable compound is less than 0.1 parts by weight, the photocationic polymerization of the photocationic polymerizable compound may not proceed sufficiently, or the photocurable resin composition If the content of the photocationic polymerization initiator is more than 10 parts by weight based on 100 parts by weight of the photocationically polymerizable compound, the photocurable resin composition is rapidly cured. It may become too much, and workability | operativity may fall or it may become easy to become a nonuniform cured | curing material.

  The photo-curable resin composition of the present invention contains a curing control agent in order to delay the curing rate of the photo-curable resin composition and impart photo post-curability to the photo-curable resin composition. Preferably it is.

  Although it does not specifically limit as said hardening control agent, For example, the aliphatic hydrocarbon which has a hydroxyl group, a polyether compound, etc. are mentioned. These curing control agents may be used alone or in combination of two or more.

  The aliphatic hydrocarbon having a hydroxyl group is not particularly limited, and examples thereof include polyfunctional hydroxyl group-containing compounds such as glycerin and pentaerythritol. These aliphatic hydrocarbons having a hydroxyl group may be used alone or in combination of two or more.

  Although it does not specifically limit as said polyether compound, For example, polyalkylene oxides, such as polyethyleneglycol, polypropylene glycol, polyoxytetramethylene glycol, 18-crown-6, 15-crown-5, 12- And crown ethers such as crown-4. These polyether compounds may be used independently and 2 or more types may be used together.

  Among the above curing control agents, polyalkylene oxide is preferably used, and in particular, polyethylene glycol and polypropylene glycol are more preferably used.

  The terminal of the polyalkylene oxide is not particularly limited, and may be, for example, a hydroxyl group, etherified or esterified with another compound, or a functional group such as an epoxy group. Among them, a hydroxyl group or an epoxy group is preferable because it has reactivity with the photocationically polymerizable compound.

  As the polyether compound, a polyalkylene oxide-added bisphenol derivative is also preferably used, and in particular, a compound having a hydroxyl group or an epoxy group at the terminal is more preferably used. Among these, although it does not specifically limit as a commercial item, For example, brand names "Lika Resin BPO-20E", "Lika Resin BEO-60E", "Lika Resin PO-20", etc. made by Shin Nippon Rika Co., Ltd. "Recar Resin" series and the like.

  The content of the curing control agent in the photocurable resin composition of the present invention may be appropriately set corresponding to the required usable time and curing time after light irradiation, and is not particularly limited. In general, however, it is preferably 0.1 to 20 parts by weight of the curing control agent with respect to 100 parts by weight of the cationic photopolymerizable compound.

  In order to further improve the mechanical properties of the cured product of the photocurable resin composition, the photocurable resin composition of the present invention may contain an inorganic filler as necessary.

  The inorganic filler is not particularly limited. For example, carbonates or bicarbonates of alkali metals or alkaline earth metals such as calcium carbonate, calcium bicarbonate, sodium carbonate, and sodium bicarbonate, colloidal silica. Inorganic powders such as talc, clay, mica, titanium oxide, inorganic hollow bodies such as glass balloons, alumina balloons and ceramic balloons, inorganic fiber bodies such as glass fibers, etc. Since the acid can be neutralized by reacting with the acid generated when the resin composition undergoes photocationic polymerization, alkali metal or alkaline earth metal carbonates or hydrogen carbonates are preferably used. These inorganic fillers may be used independently and 2 or more types may be used together.

  The inorganic filler preferably has an average particle size of 0.5 μm or less, or a difference in average refractive index from the photocationically polymerizable compound of 0.2 or less. When the average particle diameter of the inorganic filler exceeds 0.5 μm and the difference in average refractive index of the inorganic filler from the photocationically polymerizable compound exceeds 0.2, the cured product of the photocurable resin composition When the transparency becomes insufficient and, for example, a display element is produced using this photocurable resin composition, the optical characteristics of the obtained display element may be insufficient.

  In the photocurable resin composition of the present invention, in order to further improve the efficiency of the photocationic polymerization initiator and further promote the photocationic polymerization of the photocationic polymerizable compound, if necessary, A sensitizer may be contained.

  The photosensitizer is not particularly limited, and examples thereof include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo compounds, diazo compounds, halogen compounds, and photoreducible dyes. Specific examples thereof include, but are not limited to, for example, benzoin derivatives such as benzoin methyl ether and benzoin isopropyl ether, benzophenone, 2,4-dichlorobenzophenone, methyl o-benzoylbenzoate, 4, Examples thereof include benzophenone derivatives such as 4′-bis (dimethylamino) benzophenone, thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone, and anthraquinone derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone. These photosensitizers may be used independently and 2 or more types may be used together.

  Although content of the said photosensitizer in the photocurable resin composition of this invention is not specifically limited, It is 0.01- of photosensitizers with respect to 100 weight part of said photocationic polymerizable compounds. The amount is preferably 10 parts by weight.

  In the photocurable resin composition of the present invention, for example, an adhesive polymer or an adhesive imparting agent (tackifier) for improving the adhesive property is further adjusted as necessary. Viscosity modifier, thixotropic agent for imparting thixotropic properties (thixotropic agent), physical property modifier for improving mechanical properties, drying agent, coupling agent, reinforcing agent, extender Contains one or more of various known additives such as softeners (plasticizers), sagging inhibitors, antioxidants (anti-aging agents), heat stabilizers, flame retardants, antistatic agents, and organic solvents. May be.

  The method for producing the photocurable resin composition of the present invention is not particularly limited. For example, various known kneaders such as a universal mixer, a Banbury mixer, a kneader, two rolls, three rolls, and an extruder are used. Used alone or in combination, a predetermined amount of each of the photocationic polymerizable compound and the photocationic polymerization initiator, which are essential components, and a curing control agent, an inorganic filler, and a photosensitizer that may be included as necessary And kneading one or more predetermined amounts of various additives uniformly at room temperature or under heating, under normal pressure, under reduced pressure, under pressure, or under an inert gas stream, A desired photocurable resin composition can be obtained.

  The photocurable resin composition of the present invention is preferably irradiated with light containing light with a wavelength of 300 nm or more, more preferably with a wavelength of 300 to 380 nm, and may be contained as necessary with the photocationic polymerization initiator. By activating (exciting) the photosensitizer, the photocationic polymerization of the photocationically polymerizable compound proceeds and is cured.

  The light source for irradiating the light is not particularly limited as long as it is capable of irradiating light including light having a wavelength of 300 nm or more, more preferably 300 to 380 nm. For example, low pressure mercury lamp, medium pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, excimer laser, chemical lamp, black light lamp, microwave excitation mercury lamp, metal halide lamp, sodium lamp, halogen lamp, xenon lamp, fluorescent A lamp, sunlight, an electron beam irradiation apparatus, etc. are mentioned. When using these light sources, it is preferable to remove light having a wavelength of less than 300 nm using, for example, a light cut filter or the like. The various light sources may be used alone or in combination of two or more. Furthermore, examples of the irradiation procedure of the various light sources to the photocurable resin composition include simultaneous irradiation of various light sources, sequential irradiation with a time difference, combined irradiation of simultaneous irradiation and sequential irradiation, etc. The irradiation procedure may be taken.

  In curing the photocurable resin composition of the present invention, in order to further accelerate the photocationic polymerization of the photocationically polymerizable compound and further shorten the curing time, the wavelength is preferably 300 nm or more, more preferably the wavelength. In addition to irradiation with light including light of 300 to 380 nm, other curing means such as heat curing, for example, within a range that does not deteriorate the material (adhered body) to which the photocurable resin composition is applied. May be used in combination. Although the heating temperature in the case of using together the said heat curing is not specifically limited, It is preferable that it is 80 degrees C or less.

  The use is not specifically limited for the photocurable resin composition of this invention, For example, it can be used for various uses, such as an adhesive agent, a sealing agent, a single-sided tape, a double-sided tape, a sealing film. . Moreover, it can use suitably especially for transparent or semi-transparent structures like a display element through these adhesive agents, sealing agents, single-sided tapes, double-sided tapes, sealing films and the like.

  Next, the adhesive for display elements of the present invention uses the above-described photocurable resin composition of the present invention. Specifically, the adhesive for a display element of the present invention is a photocurable adhesive formed from the photocurable resin composition of the present invention, and may have a photo-curing property, Although it does not have to have light post-curing property, it is preferable to have light post-curing property because the work width is widened and workability is excellent.

  The method for producing the adhesive for a display element of the present invention is not particularly limited. For example, the photo cationic polymerizable compound and the photo cationic polymerization initiator, which are essential components, and, if necessary, are contained. For example, appropriately select the type of curing control agent, inorganic filler, photosensitizer, adhesive polymer, adhesive agent, other various additives, etc., and adjust the amount appropriately The desired adhesive for a display element can be obtained by uniformly kneading these components in the same manner as in the method for producing the photocurable resin composition of the present invention.

  Next, the bonding method of the present invention is a method of bonding display elements using the display element adhesive of the present invention, and after irradiating the display element adhesive with light, the display element adhesive The adherends are bonded and bonded together until the material is cured.

  Specifically, in the bonding method of the present invention, the display element adhesive of the present invention is applied to at least one adherend, and the display element adhesive is irradiated with light, and then the other adherend is attached. Bonding and further curing at a temperature of 80 ° C. or lower to cure the display element adhesive, or after irradiating the display element adhesive of the present invention with light, at least one of the display element adhesives The other adherend is applied and then cured at a temperature of 80 ° C. or lower to cure the display element adhesive, or the display element adhesive of the present invention is irradiated with light. It is preferable to perform this by filling the adhesive for display element between both adherends and curing the adhesive for display element by further curing at a temperature of 80 ° C. or lower.

  That is, in the bonding method of the present invention, first, the display element adhesive of the present invention is applied to at least one adherend, and then the display element adhesive is irradiated with light, and then the other adhesion is performed. The body may be bonded and post-cured at a temperature of 80 ° C. or lower to cure the display element adhesive. First, the display element adhesive of the present invention is irradiated with light. A method of applying the adhesive for display element to at least one adherend, then bonding the other adherend and further curing at a temperature of 80 ° C. or lower to cure the adhesive for display element. First, after irradiating the adhesive for display element of the present invention with light, this adhesive for display element is filled between both adherends, and further at a temperature of 80 ° C. or lower. A method of curing and curing the adhesive for display elements may be employed.

  Since the adhesive for display elements of the present invention contains the curing control agent, it has excellent light post-curing property, and the usable time after light irradiation becomes long. Thereafter, both adherends can be bonded together or filled between both adherends with good workability.

  Since the bonding method of the present invention is performed by the method as described above, it is not necessary to irradiate light from above the adherend through the adherend, and therefore the adherend is deteriorated by the influence of light. There is no. Even if both adherends are opaque and light-impermeable, adhesion or filling can be performed without hindrance.

  In the bonding method of the present invention, it is preferable to perform post-curing of the light-irradiated display element adhesive at a temperature of 80 ° C. or lower. When post-curing of the adhesive for display elements that has been irradiated with light is performed at a temperature exceeding 80 ° C., the adherend may be deteriorated by the influence of heat. In the bonding method of the present invention, the post-curing of the adhesive for display element that has been irradiated with light is performed at a temperature of 80 ° C. or lower, so that the adherend is not deteriorated by the influence of heat.

  When the display element is bonded (sealed) by the bonding method of the present invention using the display element adhesive of the present invention, for example, the following method may be used.

  First, after irradiating light to the adhesive for a display element of the present invention, the adhesive for a display element is filled in the entire gap between the substrate constituting the display element structure and the sealing plate or around the gap. Further, the display element is bonded (sealed) by performing post-curing for a predetermined time at a temperature of 80 ° C. or less to cure the display element adhesive.

  By adopting such a method, direct irradiation of light onto the display element can be avoided, so that the display element does not deteriorate due to the influence of light. Moreover, since post-curing of the adhesive for display elements irradiated with light is performed at a temperature of 80 ° C. or lower, the display elements are not deteriorated by the influence of heat.

  Next, the display element of the present invention is manufactured using the display element adhesive of the present invention and / or manufactured by the above-described bonding method of the present invention.

  Although it does not specifically limit as said display element, For example, an EL element, a liquid crystal display element, etc. are mentioned, Especially, an EL element is used suitably.

  Although it does not specifically limit as said EL element, For example, an organic EL element, an inorganic EL element, an organic-inorganic EL element etc. are mentioned.

  Although it does not specifically limit as a display element of this invention, For example, an EL element which is illustrated in FIGS. 1-3 is mentioned.

  FIG. 1 is a cross-sectional view schematically showing an example of an EL element bonded (sealed) using the display element adhesive of the present invention. FIG. 2 is a cross-sectional view schematically showing another example of an EL element bonded (sealed) using the display element adhesive of the present invention. FIG. 3 is a cross-sectional view schematically showing still another example of an EL element bonded (sealed) using the display element adhesive of the present invention.

  The photocurable resin composition of the present invention contains a photocationic polymerizable compound and a photocationic polymerization initiator, and the cured product has a total light transmittance of light having a wavelength of 380 to 780 nm in a spectrophotometer. Is 80% or more, and the glass transition temperature is 85 ° C. or more. Therefore, the cured product has low moisture permeability and excellent transparency. For example, an adhesive for display elements such as EL elements When used as (sealing agent), it is possible to effectively achieve a long life of the display element.

Moreover, the photocurable resin composition of the present invention has a moisture permeability of 150 (g / m ² · 24 h / 100 μm) measured under the condition of 85 ° C.-85% RH in accordance with JIS Z 0208 of the cured product. By using a sulfonium salt that absorbs light having a wavelength of 300 to 380 nm as a photocationic polymerization initiator or a borate salt having a boronic acid represented by the above formula (1) as a counter anion, the above effect can be obtained. Is more certain.

  Furthermore, the photocurable resin composition of the present invention has excellent photo-postcurability by containing 0.1 to 20 parts by weight of a curing controller with respect to 100 parts by weight of the photocationically polymerizable compound, Excellent workability during bonding.

  Since the adhesive for display elements of the present invention uses the photocurable resin composition of the present invention, it becomes a cured product having low moisture permeability and excellent transparency, and the adhesive for display elements ( When used as a sealing agent), the lifetime of the display element can be effectively increased.

  Since the display element of the present invention is manufactured using the above-described adhesive for display elements of the present invention and / or is manufactured by the above-described bonding method of the present invention, it has a long lifetime and long-term reliability. As well as excellent transparency and excellent optical properties.

  In order to describe the present invention in more detail, examples are given below, but the present invention is not limited to these examples.

(Example 1)
Triphenyl represented by the general formula (12) as a photocationic polymerization initiator with respect to 100 parts by weight of a bisphenol A type epoxy resin (trade name “Epicoat 828”, manufactured by Japan Epoxy Resin Co., Ltd.) as a photocationic polymerizable compound. Add 3 parts by weight of sulfonium borate salt, 10 parts by weight of polyethylene glycol (molecular weight 1000) as a curing control agent and 0.1 part by weight of silane coupling agent (trade name “KBM403”, manufactured by Shin-Etsu Chemical Co., Ltd.), and uniformly knead and knead After defoaming, a photocurable resin composition was produced.

(Comparative Example 1)
As a cationic photopolymerization initiator, instead of 3 parts by weight of triphenylsulfonium borate salt, 5 parts by weight of 50% propylene carbonate solution of sulfonium antimony salt (trade name “Adekaoptomer SP170”, manufactured by Asahi Denka Kogyo Co., Ltd.) A photocurable resin composition was produced in the same manner as in Example 1 except that.

(Comparative Example 2)
As in the case of Example 1, except that 3 parts by weight of iodonium borate salt (trade name “Rhotoinitiator 2074”, manufactured by Rhodia) was added as a cationic photopolymerization initiator instead of 3 parts by weight of triphenylsulfonium borate salt. Thus, a photocurable resin composition was produced.

  The performances (1. minimum total light transmittance, 2. glass transition temperature, 3. moisture permeability) of the photocurable resin compositions obtained in Example 1 and Comparative Examples 1 and 2 were as follows. evaluated. The results are shown in Table 1.

1. Minimum total light transmittance Using a Baker-type applicator, apply a photocurable resin composition to one glass plate (thickness 0.7 mm) so that the thickness of the coating film becomes 100 μm, and use an ultrahigh pressure mercury lamp. After irradiating light with an intensity of 40 mW for 50 seconds, the other glass plate (thickness 0.7 mm) was bonded. Then, after leaving at room temperature for 1 hour, it heated at 80 degreeC for 30 minutes, and performed postcuring. Next, using a spectrophotometer (trade name “COLOR ANALYZER TC-1800M”, manufactured by Tokyo Denshoku Co., Ltd.), the minimum total light transmittance (%) of light having a wavelength of 380 to 780 nm of the joined body obtained above was determined. It was measured.

2. Glass transition temperature After applying a photocurable resin composition to a release treatment surface of a polyethylene terephthalate (PET) film subjected to a release treatment using a Baker type applicator so that the thickness of the coating film becomes 100 μm. A 40 mW light was irradiated for 50 seconds using an ultrahigh pressure mercury lamp. Then, after leaving at room temperature for 1 hour, it heated at 80 degreeC for 30 minutes, and performed postcuring. Subsequently, the dynamic viscoelasticity measurement of the cured coating film obtained above was performed, and the glass transition temperature (° C.) was measured from the position of the tan δ peak.

3. 2. Moisture permeability The cured coating film obtained in the same manner as in the case of the glass transition temperature was cut into a predetermined size (circle with a diameter of 6 cm), and then placed on a specified cup in JIS Z 0208 where calcium chloride was installed. The periphery was fixed with wax. Next, after being left in an atmosphere of 85 ° C.-85% RH for 24 hours, the weight change was measured to determine the moisture permeability (g / m ² · 24 h / 100 μm).

  As is clear from Table 1, the cured product of the photocurable resin composition of Example 1 according to the present invention is excellent in the total light transmittance of light having a wavelength of 380 to 780 nm, has a high glass transition temperature, and has a moisture permeability. Was low.

  On the other hand, the cured product of the photocurable resin composition of Comparative Example 1 using a sulfonium antimony salt as a photocationic polymerization initiator had a low glass transition temperature and a high moisture permeability. Moreover, the cured product of the photocurable resin composition of Comparative Example 2 using iodonium borate salt as the photocationic polymerization initiator had low light total light transmittance and glass transition temperature of light having a wavelength of 380 to 780 nm.

  As described above, the photocurable resin composition of the present invention contains a photocationically polymerizable compound and a photocationic polymerization initiator, and the cured product has a wavelength of 380 to 780 nm in a spectrophotometer. Since the total light transmittance of light is 80% or more and the glass transition temperature is 85 ° C. or more, the cured product has low moisture permeability and excellent transparency, such as an electroluminescence device When used as an adhesive (sealant) for display elements, it is possible to effectively achieve a long lifetime of the display element. For example, for adhesives, sealants, single-sided It is suitably used as a photo-curable resin composition for various uses including tapes, double-sided tapes, sealing films, and display elements.

  Since the adhesive for display elements of the present invention uses the photocurable resin composition of the present invention, it becomes a cured product having low moisture permeability and excellent transparency, and the adhesive for display elements ( When used as a sealing agent), it is possible to effectively achieve a long lifetime of the display element, and it is suitably used as an adhesive (sealing agent) for the display element.

  The bonding method of the present invention is a method of bonding a display element using the display element adhesive of the present invention having light post-curing property, and the display element is irradiated with light after being irradiated with light. Since the adherends are bonded to each other until the adhesive is cured, the display element having the above-described excellent performance can be obtained efficiently and with good workability.

  Since the display element of the present invention is manufactured using the above-described adhesive for display elements of the present invention and / or is manufactured by the above-described bonding method of the present invention, it has a long lifetime and long-term reliability. In addition to being excellent in transparency, it is excellent in transparency and exhibits excellent optical characteristics, and is suitably used as a display element for various applications.

It is sectional drawing which shows typically an example of the EL element adhere | attached (sealed) using the adhesive agent for display elements of this invention. It is sectional drawing which shows typically the other example of the EL element adhere | attached (sealed) using the adhesive agent for display elements of this invention. It is sectional drawing which shows typically the further another example of the EL element adhere | attached (sealed) using the adhesive agent for display elements of this invention.

Claims (9)

  The photocationic polymerizable compound and the photocationic polymerization initiator are contained, and the cured product has a total light transmittance of 80% or more of light having a wavelength of 380 to 780 nm in a spectrophotometer, and a glass transition temperature of 85. A photocurable resin composition having a temperature of at least ° C. The cured product has a moisture permeability of 150 (g / m ² · 24h / 100 µm) or less measured under conditions of 85 ° C to 85% RH in accordance with JIS Z 0208. Photocurable resin composition.   3. The photocurable resin composition according to claim 1, wherein the cationic photopolymerization initiator is a sulfonium salt that absorbs light having a wavelength of 300 to 380 nm. The photocurable resin according to any one of claims 1 to 3, wherein the cationic photopolymerization initiator is a borate salt having a boronic acid represented by the following formula (1) as a counter anion. Composition.

  The photocurable resin according to any one of claims 1 to 4, wherein 0.1 to 20 parts by weight of a curing control agent is blended with 100 parts by weight of the cationic photopolymerizable compound. Composition.   An adhesive for display elements comprising the photocurable resin composition according to any one of claims 1 to 5.   A method of bonding display elements using the display element adhesive according to claim 6, wherein the display element adhesive is cured after the display element adhesive is irradiated with light. A bonding method characterized in that the bonded bodies are bonded and bonded together.   After applying the adhesive for display elements according to claim 6 to at least one adherend, irradiating the adhesive for display elements with light, the other adherend is bonded, and further the temperature is 80 ° C or lower. And then curing the display element adhesive, or irradiating the display element adhesive according to claim 6 with light and then applying the display element adhesive to at least one adherend. Then, the other adherend is bonded and post-cured at a temperature of 80 ° C. or lower to cure the display element adhesive, or the display element adhesive according to claim 6 is irradiated with light. Thereafter, the adhesive for display element is filled between both adherends, and further cured at a temperature of 80 ° C. or lower to cure the adhesive for display element. Method.   A display element produced by using the adhesive for a display element according to claim 6 and / or produced by the bonding method according to claim 7 or 8.

Images