TW202111073A - Sealing sheet - Google Patents

Abstract

The present invention provides a sealing sheet having a thermosetting sealant layer, the sealing sheet being characterized by satisfying a requirement (I), a requirement (II), and a requirement (III). A sealing sheet according to the present invention has a sealant layer that has a superior stickability at a normal temperature and that does not easily deform in a thermosetting process. Requirement (I): the sealant layer contains one or more types of epoxy compounds. Requirement (II): the storage modulus of the sealant layer at 23 DEG C is equal to or less than 3.0*107 Pa. Requirement (III): when the sealant layer is heated at a rate of 25 DEG C/min staring from 35 DEG C until reaching 110 DEG C and is subsequently maintained at 110 DEG C, the complex viscosity of the sealant layer is equal to or greater than 1*104 Pa.s at 250 seconds after starting the heating.

Description

Sealing sheet

The present invention relates to a sealing sheet, which includes a sealant layer that has excellent adhesion at normal temperature (meaning 23°C, the same below) and is not easily deformed during thermal hardening.

In recent years, organic EL elements have attracted attention as light-emitting elements that can emit high-intensity light by low-voltage direct current driving. However, the organic EL element has a problem that light-emitting characteristics such as light-emitting brightness, light-emitting efficiency, and light-emitting uniformity tend to decrease with the passage of time. Oxygen, moisture, etc. penetrate into the inside of the organic EL element to cause deterioration of the electrode and the organic layer, which is considered to be the cause of the above-mentioned problem of reduced light-emitting characteristics. Therefore, in the past, organic EL elements were sealed with sealing materials to prevent oxygen and moisture from entering.

For example, Patent Document 1 describes an image display device sealing material characterized by including a resin component and a curing agent, wherein the aforementioned resin component includes a biphenyl skeleton-containing epoxy resin having a weight average molecular weight within a specific range, The alicyclic skeleton-containing epoxy resin with a weight average molecular weight within a specific range, and a styrene oligomer with a weight average molecular weight within a specific range. [Prior Art Literature] [Patent Literature]

[Patent Document 1] World Patent No. 2018235824

[The problem to be solved by the invention]

As described in Patent Document 1, it is suitable to use a curable sheet-shaped adhesive as a material for forming a sealing material (hereinafter, the “sheet-shaped adhesive for forming a sealing material” may be referred to as a “sealant layer”). However, some of the hardenable sealant layers have poor adhesion at room temperature, and some require heating to soften the surface when they are attached to the object to be sealed. Furthermore, when the sealant layer has thermosetting properties, in the initial stage of the thermosetting process, the sealant layer whose fluidity is improved due to heating will be deformed due to external influences such as vibration, resulting in failure to exhibit sealing. The original sealing performance of the agent layer.

In view of the foregoing, the object of the present invention is to provide a sealing sheet including a sealant layer that has excellent adhesion at normal temperature and is not easily deformed during the thermal hardening process. [Means used to solve the problem]

In order to solve the above-mentioned problems, the present inventors conducted intensive studies on the sealant layer including epoxy compounds. As a result, it was found that the sealant layer that satisfies the conditions regarding the storage modulus at 23° C. and the conditions regarding the complex viscosity (complex viscosity) when heated under predetermined conditions has excellent adhesiveness at room temperature, and It is not easy to deform during the thermal hardening process, thereby completing the present invention.

Therefore, according to the present invention, the following sealing sheets [1] to [12] are provided.

[1] A sealing sheet comprising a thermosetting sealant layer, and characterized by satisfying the following conditions (I), (II) and (III), condition (I): the aforementioned sealing The agent layer contains one or more epoxy compounds, condition (II): the storage modulus of the aforementioned sealant layer at 23°C is 1.3×10 ⁷ Pa or less, and condition (III): when the aforementioned sealant layer is When the temperature was raised from 35°C to 110°C at a rate of 25°C/min and maintained at 110°C, the complex viscosity of the sealant layer after 250 seconds from the start of the temperature rise was 1×10 ⁴ Pa·s or more. [2] The sealing sheet according to [1], wherein the aforementioned sealant layer satisfies the following condition (IV), condition (IV): prepare a sealant layer of the same properties [sealant layer (A) and sealant layer ( B)], and using the sealant layer (A) as a test piece, the temperature is raised from 0°C to 200°C at a temperature increase rate of 10°C/min, and differential scanning calorimetry is performed to obtain the exothermic peak area [area (Α)] Then, after storing the sealant layer (B) at 23°C and a relative humidity of 50% for 7 days, it was used as a measurement sample, and the temperature was raised from 0°C at a temperature increase rate of 10°C/min. Differential scanning calorimetry is performed at 200° C., and the area of the exothermic peak [area (β)] is obtained. Based on the obtained area value, X calculated from the following formula (1) is 95% or more.

[Number 1]

[3] The sealing sheet according to [1] or [2], wherein at least one of the epoxy compounds is an epoxy compound that is liquid at 25°C. [4] The sealing sheet according to [3], wherein the content of the epoxy compound that is liquid at 25° C. is 55 mass% or more with respect to the entire sealant layer. [5] The sealing sheet according to any one of [1] to [4], wherein at least one of the epoxy compounds includes a glycidyl ether-based epoxy compound. [6] The sealing sheet according to any one of [1] to [5], wherein at least one of the epoxy compounds includes an epoxy compound having an alicyclic skeleton. [7] The sealing sheet according to any one of [1] to [6], wherein the sealing agent layer includes a hardening agent, and at least one type of hardening agent is a thermal cationic polymerization initiator. [8] The sealing sheet according to [7], wherein a curing agent including a thermal cationic polymerization initiator whose peak top temperature of the exothermic peak is 120°C or less when the differential scanning calorimetry is measured under the following conditions is used as At least one of the aforementioned hardeners, (Differential Scanning Calorimetry) A mixture of 0.1 parts by mass of thermal cationic polymerization initiator, 100 parts by mass of bisphenol A diglycidyl ether, and 0.1 parts by mass of γ-butyrolactone was used as the measurement sample, and the temperature was increased from 30 at a rate of 10°C/min. The temperature was raised to 300°C for differential scanning calorimetry. [9] The sealing sheet according to [8], wherein the hardening agent further includes a thermal cationic polymerization initiator whose peak top temperature of the exothermic peak exceeds 120°C when the differential scanning calorimetry is measured under the following conditions At least one of the aforementioned hardeners, (Differential Scanning Calorimetry) A mixture of 0.1 parts by mass of thermal cationic polymerization initiator, 100 parts by mass of bisphenol A diglycidyl ether, and 0.1 parts by mass of γ-butyrolactone was used as the measurement sample, and the temperature was increased from 30 at a rate of 10°C/min. The temperature was raised to 300°C for differential scanning calorimetry. [10] The sealing sheet according to any one of [7] to [9], wherein all of the hardeners are thermal cationic polymerization initiators. [11] The sealing sheet according to any one of [1] to [10], wherein the sealant layer includes a binder resin, and at least one type of the binder resin has a glass transition temperature (Tg) of 60°C or higher The binder resin. [12] The sealing sheet described in any one of [1] to [11] is used for sealing optical-related devices. [Effects of the invention]

According to the present invention, there is provided a sealing sheet including a sealant layer that has excellent adhesion at normal temperature and is not easily deformed during thermal hardening.

The sealing sheet of the present invention is a sealing sheet including a thermosetting sealant layer, and is characterized by satisfying the following condition (I), condition (II), and condition (III). Condition (I): The sealant layer contains one type or two or more types of epoxy compounds. Condition (II): The storage modulus of the aforementioned sealant layer at 23° C. is 1.3×10 ⁷ Pa or less. Condition (III): When the aforementioned sealant layer is heated from 35°C to 110°C at a rate of 25°C/min and maintained at 110°C, the complex viscosity of the sealant layer after 250 seconds from the start of the temperature rise is 1×10 ⁴ Pa· s above.

In the present invention, the "sealant layer" means "a sheet-like adhesive for forming a sealant". The cured product of the sealant layer is used as a sealing material. The sealant layer may be rectangular or elongated (belt-shaped).

[Conditions (I))] The sealant layer contains one type or two or more types of epoxy compounds. Since the sealant layer includes an epoxy compound, the sealant layer becomes thermosetting.

The term "epoxy compound" refers to a compound having at least one, preferably two or more epoxy groups in the molecule. In addition, in the present invention, the epoxy compound does not include the phenoxy resin described later. The epoxy group includes a group containing an ethylene oxide structure such as a glycidyl group, a glycidyl ether group, and an epoxycyclohexyl group.

The molecular weight of the epoxy compound is usually 100 to 5,000, and preferably 200 to 3,000. The epoxy equivalent of the epoxy compound is preferably 50 g/eq or more and 1000 g/eq or less, and more preferably 100 g/eq or more and 800 g/eq or less. By keeping the epoxy equivalent of the epoxy compound within the above range, a sealing material (hardened product) with high adhesive strength can be formed more efficiently. The epoxy equivalent in the present invention means a value obtained by dividing the molecular weight by the number of epoxy groups.

The content of the epoxy compound relative to the entire sealant layer is preferably 55% by mass or more, and more preferably 57 to 75% by mass. The content of the epoxy compound is 55% by mass or more with respect to the entire sealant layer, and a sealing material with high adhesive strength can be formed more efficiently.

Examples of epoxy compounds include aliphatic epoxy compounds (excluding alicyclic epoxy compounds), aromatic epoxy compounds, and alicyclic epoxy compounds. Examples of the aliphatic epoxy compound include monofunctional epoxy compounds such as glycidyl etherate of aliphatic alcohol and glycidyl ester of alkyl carboxylic acid; Polyfunctional epoxy compounds such as polyglycidyl etherate of aliphatic polyols, or alkylene oxide adducts thereof, and polyglycidyl esters of aliphatic long-chain polybasic acids.

Typical compounds of these aliphatic epoxy compounds include alkenyl glycidyl ethers such as allyl glycidyl ether; butyl glycidyl ether, 2-ethylhexyl glycidyl ether, and C12-13 mixed alkyl glycidyl ether Alkyl glycidyl ether such as glycerol ether; 1,4-butanediol diglycidyl ether, neopentyl glycol diglycidyl ether, triglycidyl ether of glycerol, triglycidyl ether of trimethylolpropane, sorbus The glycidyl ether of polyhydric alcohols such as tetraglycidyl ether of sugar alcohol, hexaglycidyl ether of dineopentaerythritol, diglycidyl ether of polyethylene glycol, and diglycidyl ether of polypropylene glycol; Polyglycidyl etherate of polyether polyol obtained by adding one or more alkylene oxides to aliphatic polyols such as methyl propane and glycerin; diglycidyl ester of aliphatic long-chain dibasic acid; Monoglycidyl ether of higher fatty alcohol, glycidyl ester of higher fatty acid, epoxidized soybean oil, epoxy octyl stearate, epoxy butyl stearate, epoxidized polybutadiene; etc.

Furthermore, a commercially available product can also be used as the aliphatic epoxy compound. Commercial products include Denacol EX-121, Denacol EX-171, Denacol EX-192, Denacol EX-211, Denacol EX-212, Denacol EX-313, Denacol EX-314, Denacol EX-321, Denacol EX -411, Denacol EX-421, Denacol EX-512, Denacol EX-521, Denacol EX-611, Denacol EX-612, Denacol EX-614, Denacol EX-622, Denacol EX-810, Denacol EX-811, Denacol EX -850, Denacol EX-851, Denacol EX-821, Denacol EX-830, Denacol EX-832, Denacol EX-841, Denacol EX-861, Denacol EX-911, Denacol EX-941, Denacol EX-920, Denacol EX -931 (the above are manufactured by Nagase Chemtex); Epolite M-1230, Epolite 40E, Epolite 100E, Epolite 200E, Epolite 400E, Epolite 70P, Epolite 200P, Epolite 400P, Epolite 1500NP, Epolite 1600, Epolite 80MF, Epolite 100MF (the above are manufactured by Kyoeisha Chemical Co., Ltd.); ADEKA GLYCIROL ED-503, ADEKA GLYCIROL ED-503G, ADEKA GLYCIROL ED-506, ADEKA GLYCIROL ED-523T (the above are manufactured by ADEKA).

Examples of aromatic epoxy compounds include phenols having at least one aromatic ring such as phenol, cresol, and butyl phenol, or mono/polyglycidyl ether compounds of alkylene oxide adducts thereof; Heterocyclic epoxy compounds; etc.

As a typical compound of these aromatic epoxy compounds, glycidyl etherate or epoxy novolak resin of bisphenol A, bisphenol F, or a compound to which alkylene oxide is further added; Mono/polyglycidyl etherate of aromatic compounds with more than 2 phenolic hydroxyl groups, such as resorcinol, hydroquinone, or catechol; Glycidyl ether compounds of aromatic compounds with more than two alcoholic hydroxyl groups, such as phenyldimethanol, phenyldiethanol, and phenyldibutanol; Glycidyl esters of polybasic acid aromatic compounds such as phthalic acid, terephthalic acid, and trimellitic acid having two or more carboxylic acids, glycidyl esters of benzoic acid, styrene oxide, or divinylbenzene Epoxy compound Epoxy compounds having a triazine skeleton such as 2,4,6-tris(glycidyloxy)-1,3,5-triazine; etc.

Furthermore, a commercially available product can also be used as the aromatic epoxy compound. Commercial products include Denacol EX-146, Denacol EX-147, Denacol EX-201, Denacol EX-203, Denacol EX-711, Denacol EX-721, ONCOAT EX-1020, ONCOAT EX-1030, ONCOAT EX -1040, ONCOAT EX-1050, ONCOAT EX-1051, ONCOAT EX-1010, ONCOAT EX-1011, ONCOAT 1012 (the above are manufactured by Nagase Chemtex); OGSOL PG-100, OGSOL EG-200, OGSOL EG-210, OGSOL EG-250 (the above are manufactured by Osaka Gas Chemical Company); HP4032, HP4032D, HP4700 (the above are manufactured by DIC); ESN-475V (the above are manufactured by Nippon Steel Chemical & Material Co., Ltd.); JER (formerly Epikote) YX8800 (the above are manufactured by Mitsubishi Chemical Corporation); Marproof G-0105SA, Marproof G-0130SP (the above are manufactured by NOF Corporation); Epiclon N-665, Epiclon HP-7200 (the above are manufactured by DIC); EOCN-1020, EOCN-102S, EOCN-103S, EOCN-104S, XD-1000, NC-3000, EPPN-501H, EPPN-501HY, EPPN-502H, NC-7000L (the above are manufactured by Nippon Kayaku Corporation); ADEKA resin EP-4000, ADEKA resin EP-4005, ADEKA resin EP-4100, ADEKA resin EP-4901 (the above are manufactured by ADEKA company); TECHMORE VG-3101L (the above are manufactured by Printec); TEPIC-FL, TEPIC-PAS, TEPIC-UC (the above are manufactured by Nissan Chemical Company); etc.

As the alicyclic epoxy compound, a polyglycidyl etherate of a polyol having at least one alicyclic structure, or a compound containing cyclohexene or cyclopentene ring is epoxidized with an oxidizing agent. Compounds containing cyclohexene oxide or cyclopentene oxide.

As typical compounds of these alicyclic epoxy compounds, hydrogenated bisphenol A diglycidyl ether, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate, 3, 4-epoxy-1-methylcyclohexyl-3,4-epoxy-1-methylhexane carboxylate, 6-methyl-3,4-epoxycyclohexylmethyl-6-methyl- 3,4-epoxycyclohexane carboxylate, 3,4-epoxy-3-methylcyclohexylmethyl-3,4-epoxy-3-methylcyclohexane carboxylate, 3,4 -Epoxy-5-methylcyclohexylmethyl-3,4-epoxy-5-methylcyclohexanecarboxylate, bis(3,4-epoxycyclohexylmethyl)adipate, 3 ,4-Epoxy-6-methylcyclohexane carboxylate, methylene bis(3,4-epoxycyclohexane), propane-2,2-diyl-bis(3,4-epoxy Cyclohexane), 2,2-bis(3,4-epoxycyclohexyl) propane, dicyclopentadiene diepoxide, ethylene bis(3,4-epoxycyclohexane carboxylic acid) Ester), dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1-epoxyethyl-3,4-epoxycyclohexane, 1 , 2-Epoxy-2-epoxyethyl cyclohexane, α-pinene oxide, limonene dioxide, etc.

Furthermore, a commercially available product can also be used as the alicyclic epoxy compound. As commercially available products, CELLOXIDE 2021P, CELLOXIDE 2081, CELLOXIDE 2000, CELLOXIDE 3000 (the above are manufactured by Daicel); Epote 4000 (manufactured by Kyoeisha Chemical Co., Ltd.); YX8000, YX8034 (the above are manufactured by Mitsubishi Chemical Corporation) Manufactured); ADEKA resin EP-4088S, ADEKA resin EP-4088L, ADEKA resin EP-4080E (the above are manufactured by ADEKA company); etc.

These epoxy compounds may be used individually by 1 type, or may be used in combination of 2 or more types.

At least one kind of epoxy compound is preferably an epoxy compound that is liquid at 25°C. The so-called "liquid at 25°C" means that it has fluidity at 25°C. The epoxy compound preferably has a viscosity of 2 to 10,000 mPa·s measured at 25° C. and 1.0 rpm using an E-type viscometer. By using an epoxy compound that is liquid at 25°C, it becomes easy to form a sealant layer that satisfies the condition (II).

When the sealant layer includes an epoxy compound that is liquid at 25°C, from the viewpoint of preventing the edge portion of the sealant layer from accidentally adhering to other objects, the content of the above-mentioned epoxy compound relative to the entire sealant layer is 55 ~70% by mass is preferred, and 57~65% by mass is preferred. Since the content of the epoxy compound that is liquid at 25° C. is 55% by mass or more with respect to the entire sealant layer, it becomes easy to form a sealant layer that satisfies the condition (II).

At least one kind of epoxy compound is preferably an epoxy compound containing a glycidyl ether group. The reactivity of glycidyl ether groups is not so high compared to epoxycyclohexyl groups and the like. Therefore, the use of epoxy compounds including glycidyl ether groups can provide a sealing sheet with more excellent storage stability.

When the sealant layer includes an epoxy compound having a glycidyl ether group, its content is preferably 90% by mass or more with respect to the total amount of the epoxy compound, and more preferably 95-100% by mass. Since the content of the epoxy compound having a glycidyl ether group is 90% by mass or more with respect to the total amount of the epoxy compound, a sealing sheet with more excellent storage stability can be obtained.

At least one kind of epoxy compound is preferably an epoxy compound including an alicyclic skeleton. The use of an epoxy compound including an alicyclic skeleton facilitates the curing reaction due to cationic polymerization, has a low relative dielectric constant, and is easy to form a sealant layer with excellent colorless transparency.

When the sealant layer includes an epoxy compound having an alicyclic skeleton, its content relative to the total amount of the epoxy compound is preferably 80% by mass or more, and more preferably 90-100% by mass. Since the content of the epoxy compound having an alicyclic skeleton is 80% by mass or more with respect to the total amount of the epoxy compound, the curing reaction due to cationic polymerization becomes easy to proceed. Furthermore, the relative dielectric constant is low, and it becomes easy to form a sealant layer excellent in colorless and transparency.

[Condition (II))] The storage modulus of the sealant layer at 23° C. is 1.3×10 ⁷ Pa or less. Since the storage modulus of the sealant layer at 23° C. is 1.3×10 ⁷ Pa or less, the sealant layer becomes excellent in adhesion at normal temperature. The storage modulus of the sealant layer at 23°C is ^{preferably 1.1×10 7} Pa or less, and preferably 1.0×10 ⁷ Pa or less. As long as the fixed shape can be maintained, the lower limit of the storage modulus of the sealant layer at 23°C is not particularly limited, and the storage modulus of the sealant layer at 23°C is usually 5.0×10 ⁴ Pa or more. Furthermore, from the viewpoint of preventing the edge portion of the sealant layer from accidentally adhering to other objects, the storage modulus of the sealant layer at 23°C is preferably 3.0×10 ⁵ Pa or more, and 9.5×10 ⁵ Pa The above is better. The storage modulus of the sealant layer at 23° C. can be measured according to the method described in the examples.

The storage modulus of the sealant layer at 23°C tends to decrease as the amount of the liquid component in the sealant layer increases. Therefore, by adjusting the state (solid, liquid) and content of the epoxy compound used, it is possible to form a sealant layer that satisfies the condition (II) more efficiently.

[Condition (III))] When the sealing layer is heated from 35°C to 110°C at a rate of 25°C/min and maintained at 110°C, the complex viscosity of the sealant layer after 250 seconds from the start of the temperature rise (hereinafter sometimes referred to here) The complex viscosity under the measurement conditions is described as "complex viscosity (Y)") is 1×10 ⁴ Pa·s or more. By setting the complex viscosity (Y) to 1×10 ⁴ Pa·s or more, the hardening reaction starts at a relatively early stage in the thermal hardening process. In this way, the sealant layer of the sealing sheet of the present invention hardens in a state where the fluidity is hardly improved due to the temperature rise, and therefore is not easily deformed during the hardening process. The complex viscosity (Y) is preferably 1×10 ⁴ to 1×10 ⁶ Pa·s, and more preferably 1×10 ⁵ to 1×10 ⁶ Pa·s. The complex viscosity (Y) can be measured according to the method described in the examples.

As the epoxy compound reacts at a lower temperature, the value of the complex viscosity (Y) becomes larger. Therefore, by adjusting the type and amount of the curing agent according to the reactivity of the epoxy compound used, it is possible to form a sealant layer that satisfies the condition (III) more efficiently. For example, as described later, a low-temperature reactive thermal cationic polymerization initiator can be used as a hardener to increase the value of the complex viscosity (Y).

[Condition (IV))] The sealant layer preferably satisfies the following condition (IV). Condition (IV): Prepare the sealant layer [sealant layer (A) and sealant layer (B)] with the same properties, and use the sealant layer (A) as a test piece. The temperature was raised from 0°C to 200°C to perform differential scanning calorimetry, and the area of the exothermic peak [area (α)] was obtained. Next, the sealant layer (B) was stored at 23°C and a relative humidity of 50% 7 Days later, it was used as a measurement sample, and the differential scanning calorimetry was performed at a temperature increase rate of 10°C/min from 0°C to 200°C, and the area of the exothermic peak [area (β)] was obtained based on the As for the obtained area value, X calculated by the following formula (1) is 95% or more.

[Number 2]

Here, the "sealant layer of the same property" means a plurality of sealant layers having substantially the same composition and physical properties. For example, two sealant layers obtained by cutting one sealant layer into two layers belong to sealant layers of the same nature [sealant layer (A) and sealant layer (B)]. Furthermore, even if the two sealant layers are not obtained from one sealant layer, they are each obtained from another sealant layer, for example, two layers obtained from a sealant layer that has the same manufacturing number and is sold as a product The sealant layer is also a sealant layer with the same properties [sealant layer (A) and sealant layer (B)]. In addition, the "area of the exothermic peak" means the area of the area surrounded by the base line obtained from the part other than the exothermic peak of the DSC curve and the DSC curve.

The sealant layer (A) and the sealant layer (B) should preferably have the state of the sealant layer at the moment when the sealing sheet is manufactured. Therefore, it is better to store the sealant layer (A) and the sealant layer (B) at -30～+10℃ during the period after the sealing sheet is manufactured and before the above-mentioned measurement. It is better to store at +5℃.

As described above, the sealant layer of the sealing sheet of the present invention satisfies the condition (III). However, the sealant layer that satisfies the condition (III) may undergo a hardening reaction at a relatively low temperature, and the storage stability may be poor.

In this regard, the sealant layer that satisfies the condition (IV) hardly undergoes a hardening reaction even when stored in an environment of 23° C. and a relative humidity of 50% for 7 days, and has excellent storage stability.

By using an epoxy compound having a glycidyl ether group as the epoxy compound, or adjusting the amount according to the reactivity of the hardener, a sealant layer that satisfies the condition (IV) can be efficiently formed.

[hardener] The sealant layer may also include a hardener. By making the sealant layer include a hardening agent, the hardenability of the sealant layer can be further improved. The hardener is not particularly limited as long as it can initiate a hardening reaction, but a hardening agent that initiates a hardening reaction by heating is preferred. Examples of the hardener include thermal cationic polymerization initiators and other hardeners. Examples of hardeners other than the thermal cationic polymerization initiator include tertiary amines such as benzylmethylamine, 2,4,6-dimethylaminomethylphenol; 2-methylimidazole, 3- Imidazole compounds such as ethyl-4-methylimidazole and 2-heptadecylimidazole; Lewis acids such as boron trifluoride/monoethylamine complexes and boron trifluoride/piperazine complexes; etc.

The curing agent may be used singly or in combination of two or more kinds. The content of the hardener is not particularly limited, and relative to 100 parts by mass of the epoxy compound, preferably 0.1-15 parts by mass, preferably 1-10 parts by mass, and more preferably 1-5 parts by mass .

The sealant layer preferably includes at least one type of a thermal cationic polymerization initiator as a hardener. By using a thermal cationic polymerization initiator, it becomes easy to control the curability of the sealant layer close to room temperature, and it is possible to form a sealant layer that satisfies the condition (III) more efficiently.

The thermal cationic polymerization initiator is a compound capable of generating cationic species that initiate polymerization by heating. Examples of the thermal cationic polymerization initiator include sulfonium (Sulfonium) salt, quaternary ammonium salt, phosphonium salt, diazonium (Diazonium) salt, and iodonium (iodonium) salt.

Examples of the sulfonate include triphenyl tetrafluoroborate, triphenyl hexafluoroantimonate, triphenyl hexafluoroarsenate (triphenylsulphonium hexafluoroarsenate), and ginseng (4-methoxyphenyl). Hexafluoroarsenate, diphenyl(4-phenylthiophenyl) hexafluoroarsenate, (4-acetoxyphenyl)methyl(2-methylbenzyl)4(pentafluoro Phenyl) borate sulfonate, (4-hydroxyphenyl) methyl (4-methylbenzyl) tetra (pentafluorophenyl) borate sulfonate, (4-acetoxyphenyl) benzyl (methyl ) Four (pentafluorophenyl) borate sulfonium salt, benzyl (4-hydroxyphenyl) (methyl) four (pentafluorophenyl) borate sulfonate, etc.

It is also possible to use a commercially available product as the aqua salt. Commercially available products include Adeka Opton SP-150, Adeka Opton SP-170, Adeka Opton CP-66, Adeka Opton CP-77 (manufactured by Asahi Denka), Sunaid SI-60L, Sunaid SI-80L , Sunaid SI-100L, Sunaid SI-B2A, Sunaid SI-B3, Sunaid SI-B3A, Sunaid SI-B7 (manufactured by Sanxin Chemical Company), CYRACURE UVI-6974, CYRACURE UVI-6990 (by Union Carbide (Manufactured by Union Carbide), UVI-508, UVI-509 (manufactured by GE/General Electric), FC-508, FC-509 (the above are manufactured by Minnesota Mining and Manufacturing, 3M), CD-1010, CD-1011 (manufactured by Sartomer Company above), CI series products (manufactured by Japan Soda Company above), etc.

Examples of quaternary ammonium salts include tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetrabutyl ammonium hydrogen sulfate, tetraethylammonium tetrafluoroborate, and tetratoluenesulfonate Ethylammonium, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-dimethyl-N-benzylanilinium hexafluoroantimonate, N,N-dimethyl-N-benzylanilinium tetrafluoroborate Salt, N,N-dimethyl-N-benzylpyridinium hexafluoroantimonate, N,N-diethyl-N-benzyltrifluoromethanesulfonate N,N-dimethyl-N-(4-methoxybenzyl) pyridinium hexafluoroantimonate, N,N-dimethyl-N-(4-methoxybenzyl) pyridinium hexafluoroantimonate, N,N -Diethyl-N-(4-methoxybenzyl) toluidinium hexafluoroantimonate (N,N-diethyl-N-(4-methoxybenzyl) toluidinium hexafluoroantimonate) etc.

Examples of the phosphonium salt include ethyltriphenylphosphonium hexafluoroantimonate, tetrabutylphosphonium hexafluoroantimonate, and the like.

As the diazonium salt, AMERICURE (manufactured by American Can Corporation), ULTRASET (manufactured by Asahi Denka Co., Ltd.), and the like can be cited.

Examples of iodonium salts include diphenyliodonium hexafluoroarsenate, bis(4-chlorophenyl)iodonium hexafluoroarsenate, and bis(4-bromophenyl)iodonium hexafluoroarsenate. , Phenyl (4-methoxyphenyl) iodonium hexafluoroarsenate, etc. Furthermore, as commercially available products, UV-9310C (manufactured by Toshiba Silicone), Photoinitiator 2074 (manufactured by Rhone-Poulenc), and UVE series products (manufactured by Qiwei /General Electric Company), FC series products (manufactured by Minnesota Mining and Manufacturing (3M) Company), etc.

The thermal cationic polymerization initiator may be used singly or in combination of two or more kinds.

The sealant layer includes a thermal cationic polymerization initiator whose peak top temperature of the exothermic peak is 120°C or less when the differential scanning calorimetry is measured under the following conditions (hereinafter sometimes referred to as "thermal cationic polymerization initiator (P )”) is better.

(Conditions for Differential Scanning Calorimetry) A mixture of 0.1 parts by mass of thermal cationic polymerization initiator, 100 parts by mass of bisphenol A diglycidyl ether, and 0.1 parts by mass of γ-butyrolactone was used as the measurement sample, and the temperature was increased from 30 at a rate of 10°C/min. The temperature was raised to 300°C for differential scanning calorimetry.

The thermal cationic polymerization initiator (P) is a low-temperature reactive thermal cationic polymerization initiator. Therefore, the sealant layer including the thermal cationic polymerization initiator (P) becomes easy to satisfy the condition (III). Examples of the thermal cationic polymerization initiator (P) include (4-acetoxyphenyl) methyl (2-methylbenzyl) tetra (pentafluorophenyl) borate, (4-hydroxybenzene) Base) methyl (4-methylbenzyl) sulfonate (pentafluorophenyl) borate, (4-acetoxyphenyl) benzyl (methyl) sulfonate (pentafluorophenyl) borate. In addition, as commercially available products of the thermal cationic polymerization initiator (P), Sunaid SI-B2A, Sunaid SI-B3A, and Sunaid SI-B7 (manufactured by Sanshin Chemical Co., Ltd. above) can be cited.

When the sealant layer includes a thermal cationic polymerization initiator (P), a thermal cationic polymerization initiator whose peak top temperature of the exothermic peak exceeds 120°C when the differential scanning calorimetry is measured under the following conditions (below Sometimes called "thermal cationic polymerization initiator (Q)") is better.

The thermal cationic polymerization initiator (Q) is a high-temperature reactive thermal cationic polymerization initiator. Therefore, the sealant layer including the thermal cationic polymerization initiator (Q) becomes easy to satisfy the condition (IV). From the viewpoint of preventing the curing temperature of the sealant layer from becoming too high, the peak top temperature of the exothermic peak of the thermal cationic polymerization initiator (Q) is preferably 170° C. or less. Examples of the thermal cationic polymerization initiator (Q) include benzyl (4-hydroxyphenyl) (methyl) sulfonate (pentafluorophenyl) borate. In addition, as a commercially available product of the thermal cationic polymerization initiator (Q), Sunaid SI-B3 (manufactured by Sanshin Chemical Co., Ltd.) can be cited.

When the sealant layer includes a thermal cationic polymerization initiator (P) and a thermal cationic polymerization initiator (Q), the weight ratio [thermal cationic polymerization initiator (P): thermal cationic polymerization initiator (Q)] 20:80 to 80:20 is preferred, and 35:65 to 65:35 is preferred. Since the weight ratio of the thermal cationic polymerization initiator (P) to the thermal cationic polymerization initiator (Q) is within the above range, it can have a sealant layer in which the hardening reaction starts at a relatively early stage in the thermal hardening process , And can efficiently obtain a sealing sheet with excellent storage stability.

In the sealing sheet of the present invention, all the hardeners contained in the sealing agent layer are preferably thermal cationic polymerization initiators. If a hardener other than the thermal cationic polymerization initiator is used, the sealant layer may be colored or the transparency of the sealant layer may decrease. On the other hand, when a thermal cationic polymerization initiator is used, the above-mentioned problems are unlikely to occur. Therefore, all the hardeners contained in the sealant layer are thermal cationic polymerization initiators, which can efficiently form colorless Sealant layer with excellent transparency.

[Binder resin] The sealant layer may also include a binder resin. The shape retention and handleability of the sealant layer including the adhesive resin become excellent. The weight average molecular weight (Mw) of the binder resin is not particularly limited. However, due to the better compatibility with epoxy compounds and excellent shape retention, it is preferably 10,000 or more, preferably 10,000-1,000,000, And 10,000-800,000 is more preferable. Tetrahydrofuran (THF) can be used as a solvent for gel permeation chromatography (gel permeation chromatography, GPC), and the measured standard polystyrene conversion value is the weight average molecular weight (Mw) of the binder resin.

When the sealant layer includes adhesive resin, relative to the entire sealant layer, the content of the adhesive resin (when two or more types of adhesive resins are included, the total amount) is preferably 20 to 43% by mass, and 23 ~40% by mass is preferred. When the content of the binder resin is within the above range, it becomes easy to obtain a sealant layer that is excellent in shape retention and has sufficient adhesive force.

The glass transition temperature (Tg) of the binder resin is not particularly limited, but is preferably 60°C or higher, preferably 90°C or higher, and more preferably 110°C or higher. Making the glass transition temperature (Tg) of the adhesive resin 60°C or higher makes it easy to increase the storage modulus of the cured product of the adhesive layer. Furthermore, by making the glass transition temperature (Tg) of the binder resin 90° C. or higher, it is possible to efficiently form a sealant layer excellent in shape retention.

Examples of the binder resin include phenoxy resins, modified olefin resins, and acetal resins. Among them, phenoxy resin is preferred as the binder resin, because a sealant layer excellent in shape retention can be easily obtained.

The phenoxy resin generally corresponds to a high molecular weight epoxy resin, and means a resin having a degree of polymerization of about 100 or more. The epoxy equivalent of the phenoxy resin is preferably 5,000 or more, and more preferably 7,000 or more. The epoxy equivalent value can be measured according to JIS K7236.

Examples of phenoxy resins include bisphenol A type, bisphenol F type, bisphenol S type phenoxy resin, copolymer type phenoxy resin of bisphenol A type and bisphenol F type, and distillates thereof , Naphthalene type phenoxy resin, novolak type phenoxy resin, biphenyl type phenoxy resin, cyclopentadiene type phenoxy resin, etc. These phenoxy resins may be used individually by 1 type, or may be used in combination of 2 or more types.

The phenoxy resin can be obtained by the method of reacting bifunctional phenols and epihalohydrin to a high molecular weight, or the addition polymerization reaction of bifunctional epoxy resin and bifunctional phenols. For example, it can be obtained by reacting bifunctional phenols and epihalohydrin at a temperature of 40 to 120°C in an inert solvent in the presence of an alkali metal hydroxide. Furthermore, in the presence of catalysts such as alkali metal compounds, organophosphorus compounds, cyclic amine compounds, etc., the boiling point of amine solvents, ether solvents, ketone solvents, lactone solvents, alcohol solvents, etc. It is obtained by heating a bifunctional epoxy resin and a bifunctional phenol to a reaction solid content concentration of 50% by weight or less in an organic solvent of 120°C or higher to 50 to 200°C to perform an addition polymerization reaction.

The bifunctional phenols are not particularly limited as long as they are compounds having two phenolic hydroxyl groups. For example, monocyclic bifunctional phenols such as hydroquinone, 2-bromohydroquinone, resorcinol, and catechol, bisphenol A, bisphenol F, bisphenol AD, bisphenol Bisphenols such as S, dihydroxybiphenyls such as 4,4'-dihydroxybiphenyl, dihydroxyphenyl ethers such as bis(4-hydroxyphenyl) ether; Compounds such as linear alkyl groups, branched chain alkyl groups, aromatic groups, hydroxymethyl groups, allyl groups, cyclic aliphatic groups, halogens (tetrabromobisphenol A, etc.), nitro groups, etc. are introduced into the ring. Polycyclic bifunctional phenols with linear alkyl groups, branched chain alkyl groups, allyl groups, substituted allyl groups, cyclic aliphatic groups, and alkoxycarbonyl groups introduced into the central carbon atom of the phenol skeleton; etc. .

Examples of epihalohydrins include epichlorohydrin, epibromohydrin, epiiodohydrin, and the like.

Furthermore, in the present invention, a commercially available product can be used as the phenoxy resin. For example, the product names manufactured by Mitsubishi Chemical Corporation: YX7200, YL7553, YL6794, YL7213, YL7290, YL7482, and the product names manufactured by Mitsubishi Chemical Corporation: YX8100 (phenoxy resin containing a bisphenol S skeleton), Toto Kasei Corporation Product names manufactured by FX280, FX293, FX293S (phenoxy resin containing fluorene skeleton), product names manufactured by Mitsubishi Chemical Corporation: jER1256, jER4250, product names manufactured by Nippon Steel Chemical Materials Corporation: YP-50, YP-50S (Either one is a phenoxy resin containing a bisphenol A skeleton), product name manufactured by Mitsubishi Chemical Corporation: YX6954 (a phenoxy resin containing a bisphenol acetophenone skeleton), a product manufactured by Nippon Steel Chemical Materials Co., Ltd. Name: ZX-1356-2, etc.

[Silane Coupling Agent] The sealant layer may also include a silane coupling agent. By including the silane coupling agent, it becomes easier to obtain a sealant layer with better wet-heat durability.

As the silane coupling agent, a known silane coupling agent can be used. Among them, an organosilicon compound having at least one alkoxysilyl group in the molecule is preferred. As the silane coupling agent, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyl Silane coupling agents with (meth)acryloyl groups such as methyl diethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-propenoxypropyltrimethoxysilane, etc. ; Vinyl trimethoxy silane, vinyl triethoxy silane, dimethoxy methyl vinyl silane, diethoxy methyl vinyl silane, trichloro vinyl silane, vinyl ginseng (2-methoxy Ethoxy) silane and other silane coupling agents with vinyl groups; 2-(3,4-epoxycyclohexyl) ethyl trimethoxy silane, 3-glycidoxy propyl trimethoxy silane, 3-glycidoxy propyl methyl diethoxy silane, Silicone coupling agents with epoxy groups such as 3-glycidoxypropyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, etc.; Silane coupling agents with styryl groups such as p-styryltrimethoxysilane and p-styryltrimethoxysilane;

N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-( 2-aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilane -N-(1,3-dimethylbutylidene) propylamine (3-triethoxysilyl-N- (1,3-dimethylbutylidene) propylamine), N-phenyl-3-aminopropyl trimethoxysilane, N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride and other silane coupling agents with amino groups; Silane coupling agents with ureido groups such as 3-ureidopropyltrimethoxysilane and 3-ureidopropyltriethoxysilane; Silane coupling agents with halogen atoms such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane; Silane coupling agents with mercapto groups such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; Silane coupling agents with sulfide groups such as bis(triethoxysilylpropyl) tetrasulfide and bis(triethoxysilylpropyl) tetrasulfide; Silane coupling agents with isocyanate groups such as 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, etc.; Allyl trichlorosilane, allyl triethoxy silane, allyl trimethoxy silane and other silane coupling agents with allyl groups; Silane coupling agents with hydroxyl groups such as 3-hydroxypropyltrimethoxysilane and 3-hydroxypropyltriethoxysilane; etc. The above-mentioned silane coupling agent may be used singly or in combination of two or more kinds.

When the sealant layer includes a silane coupling agent, relative to the entire sealant layer, the content of the silane coupling agent is preferably 0.01-5 mass%, and more preferably 0.05-1 mass%.

[Other ingredients] The sealant layer may include other components within a range that does not hinder the effects of the present invention. Examples of other components include additives such as ultraviolet absorbers, antistatic agents, light stabilizers, antioxidants, resin stabilizers, fillers, pigments, extenders, and softeners. These components may be used individually by 1 type, or may be used in combination of 2 or more types. In the case where the sealant layer includes the above-mentioned additives, the content can be appropriately determined according to the purpose.

[Sealant layer] The thickness of the sealant layer is usually 1-50 μm, preferably 1-25 μm, and preferably 5-25 μm. The sealant layer having a thickness within the above-mentioned range is suitable as a forming material of the sealant. The thickness of the sealant layer can be measured using a known thickness gauge in accordance with JIS K 7130 (1999).

The method of forming the sealant layer is not particularly limited. For example, a casting method can be used to form the sealant layer. In the case of manufacturing the sealant layer by the casting method, a sealant composition including the ingredients constituting the sealant layer is prepared, and the obtained sealant composition is applied to a substrate or a release film using a known method. On the surface of the peeling layer of the peeling treatment, the obtained coating film is dried to form a sealant layer.

The sealant composition may also include a solvent. Examples of solvents include aromatic hydrocarbon solvents such as benzene and toluene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; n-pentane, Aliphatic hydrocarbon solvents such as n-hexane and n-heptane; alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, and methylcyclohexane; etc. The above-mentioned solvents may be used singly or in combination of two or more kinds. The content of the solvent can be appropriately determined in consideration of coating properties and the like.

Examples of the coating method of the sealant composition include spin coating, spray coating, bar coating, knife coating, and roll coating. ) Method, blade coating method, die coating method, gravure coating method, etc.

As a method of drying the coating film, hot air drying, hot roll drying, infrared irradiation, and conventionally known drying methods can be cited. As the conditions for drying the coating film, for example, drying is performed at 80 to 150°C for 30 seconds to 5 minutes.

The sealant layer has thermosetting properties. That is, by heating the sealant layer, at least the epoxy group of the epoxy compound reacts to harden the sealant layer.

The conditions for thermally hardening the sealant layer are not particularly limited. The heating temperature is usually 80 to 200°C, preferably 90 to 150°C. The heating time is usually 30 minutes to 12 hours, preferably 1 to 6 hours.

The storage modulus at 90°C of the cured sealant layer obtained by curing the sealant layer is preferably 1×10 ⁸ Pa or more, and more preferably 1×10 ^{9 to} 1×10 ¹¹ Pa. The hardened sealant layer with a storage modulus of 1×10 ⁸ Pa or more at 90°C has excellent sealing properties and is therefore more suitable as a sealing material. Furthermore, after the cured sealant layer is formed, it becomes easy to prevent cracking and peeling of the cured sealant layer during the manufacturing process of the device sealing body.

[Sealing sheet] The sealing sheet of the present invention has the above-mentioned sealant layer. In addition to the sealant layer, the sealing sheet of the present invention may also include a base material, a release film, a functional film, and the like.

Generally, a resin film can be used as a substrate. As the resin component of the resin film, polyimide, polyimide, polyimide imide, polyphenylene ether, polyether ketone, polyether ether ketone, polyolefin, polyester, polycarbonate, poly Waste, polyether, polyphenylene sulfide, polyarylate, acrylic resin, cycloolefin polymer, aromatic polymer, polyurethane polymer, etc. The thickness of the substrate is not particularly limited, but is preferably 10 to 500 μm, preferably 10 to 300 μm, and more preferably 15 to 200 μm.

The peeling film serves as a support in the manufacturing process of the sealing sheet, and as a protective sheet for the sealant layer before the sealing sheet is used. In addition, when the sealing sheet of the present invention is used, the release film is usually peeled and removed.

A conventionally known release film can be used as the release film. For example, the peeling film which has the peeling layer which carried out the peeling process with a peeling agent on the base material for peeling films is mentioned. Examples of the substrate for the release film include paper substrates such as glassine, coated paper, and forest paper; laminated paper in which thermoplastic resins such as polyethylene are laminated on the above-mentioned paper substrate; Plastic films such as polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, polypropylene resin, polyethylene resin, etc.; etc.

Examples of the release agent include rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins, long-chain alkane resins, alkyd resins, fluorine resins, and the like. The thickness of the release film is not particularly limited, and is usually about 20 to 250 μm.

When the sealing sheet of the present invention includes a release film, each of both sides of the sealant layer may include a total of two release films per layer, or only one side of the sealant layer may include the release film.

As a functional film, a conductive film, a gas barrier film, an anti-reflection film, a retardation film, a viewing angle improvement film, a brightness improvement film, etc. are mentioned. Among them, for example, a film having a film of a metal or an inorganic compound can be cited as the gas barrier film. The thickness of the functional film is not particularly limited, and is usually 5 to 200 μm, preferably 10 to 100 μm.

The sealant layer of the sealing sheet of the present invention is suitable for use as a material for forming a sealing material of an electronic device. Among the electronic devices, optical-related devices such as light-emitting devices, light-receiving devices, and display devices are preferred. Examples of optical related devices include organic EL elements such as organic EL displays and organic EL lighting; liquid crystal elements such as liquid crystal displays; electronic paper elements; solar cell elements; light-emitting diodes; and the like.

The method of sealing an electronic device using the sealing sheet of the present invention is not particularly limited. For example, the sealant layer of the sealing sheet of the present invention can be attached to the target electronic device, and then the sealant layer can be hardened by the above-mentioned method to seal the electronic device. [Example]

Hereinafter, examples are listed to illustrate the present invention in more detail. However, the present invention is not limited to the following examples.

[Compounds used in Examples or Comparative Examples] ・Epoxy compound (A1): Hydrogenated bisphenol A epoxy resin [manufactured by Mitsubishi Chemical Corporation, trade name: YX8000, epoxy equivalent: 205g/eq] ・Epoxy compound (A2): 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate [manufactured by Daicel, product name: CELLOXIDE 2021P, ring Oxygen equivalent: 128～145g/eq] ・Phenoxy resin (B1): (manufactured by Mitsubishi Chemical Corporation, trade name: YX7200B35, glass transition temperature (Tg): 150°C) ・Thermal cationic polymerization initiator (C1): (4-hydroxyphenyl) methyl (4-methylbenzyl) tetrakis (pentafluorophenyl) borate (manufactured by Sanshin Chemical Co., Ltd., trade name: Sunaid SI-B7) ・Thermal cationic polymerization initiator (C2): Benzyl (4-hydroxyphenyl) (methyl) Si (pentafluorophenyl) borate (manufactured by Sanshin Chemical Co., Ltd., trade name: Sunaid SI-B3) ) ・Silane coupling agent (D1): 8-glycidoxy octyl trimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name: KBM4803)

[Reactivity evaluation of thermal cationic polymerization initiator] A mixture of 0.1 parts by mass of thermal cationic polymerization initiator, 100 parts by mass of bisphenol A diglycidyl ether (manufactured by Mitsubishi Chemical Corporation, jER828), and 0.1 parts by mass of γ-butyrolactone was used as the measurement sample and When the temperature was raised from 30°C to 300°C at a temperature rise rate of 10°C/min and differential scanning calorimetry was performed, the peak top temperature of the exothermic peak was 105°C. On the other hand, when the thermal cationic polymerization initiator (C2) is used instead of the thermal cationic polymerization initiator (C1), the peak top temperature of the exothermic peak at this time is 140°C.

[Example 1] 170 parts by mass of epoxy compound (A1), 100 parts by mass of phenoxy resin (B1), 1.5 parts by mass of thermal cationic polymerization initiator (C1), and 1.5 parts by mass of thermal cationic polymerization initiator (C2) ), 0.2 parts by mass of silane coupling agent (D1) is dissolved in methyl ethyl ketone to prepare a coating solution. This coating solution was applied to the peeling film (the first peeling film, manufactured by Lintec, trade name: SP-PET752150) on the peel-off treated surface, and the resulting coating film was applied to 100 After drying for 2 minutes at °C, a sealant layer having a thickness of 15 μm was further obtained. The peeling-treated surface of another peeling film (the second peeling film, manufactured by Lintec, trade name: SP-PET381130) was attached to the sealant layer to obtain a sealing sheet.

[Examples 2 to 3, Comparative Examples 1 and 2] The sealing sheet was obtained in the same manner as in Example 1 except that the types and amounts of the components constituting the sealant layer were changed to those described in Table 1.

The following tests were performed on the sealing sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in Table 1.

[Measurement of the storage modulus of the sealant layer at 23°C] The sealant layers of the sealing sheets obtained in the Examples and Comparative Examples were laminated at 23° C. using a laminator to obtain a test sheet with a thickness of approximately 1 mm. For the obtained test piece, a dynamic viscoelasticity measuring device (manufactured by Anton Paar, trade name: Physica MCR301) was used at a frequency of 1 Hz, a strain of 1%, and a heating rate of 3°C/min. Under the conditions, the storage modulus is measured in the range of -20～150℃. The measurement results at 23°C are shown in Table 1.

[Evaluation of the applicability of the sealant layer to the object to be sealed] The sealing sheets obtained in the examples and comparative examples were cut to obtain a test piece with a width of 50 mm and a length of 150 mm. The sealant layer exposed by peeling the second release film of the obtained test piece was placed on an alkali-free glass plate under the conditions of a temperature of 23°C and a relative humidity of 50%, and a pressure roller was used to apply a 0.5 MPa pressure. The state where the sealant layer floated from the alkali-free glass plate was observed, and those without floating were evaluated as A, and those with floating were evaluated as B.

[The complex viscosity of the sealant layer during the heating process] The sealant layers of the sealing sheets obtained in the examples and comparative examples were laminated under the conditions of 23° C. and a relative humidity of 50% to obtain a test sheet with a thickness of approximately 1 mm. For the obtained test piece, a dynamic viscoelasticity measuring device (manufactured by TA Instrument Company, trade name: ARES) was used at a frequency of 1 Hz, a strain of 0.1%, and a heating rate of 25°C/min (at After reaching 110°C, maintain 110°C), and measure the complex viscosity in the range of 35～110°C. The complex viscosity of the test piece after 250 seconds from the start of the temperature rise is shown in Table 1.

[Evaluation of shape retention of sealant layer during thermal hardening] The second release film of the sealing sheet obtained in the Examples and Comparative Examples was peeled off and the exposed sealant layer was attached to an alkali-free glass plate, and then cut into a size of 50 mm in width × 50 mm in length to obtain a test sheet. The sealant layer exposed by peeling the first release film from the test piece was placed on an alkali-free glass plate at a temperature of 23° C. and a relative humidity of 50%, and a pressure roller was used to apply a pressure of 0.5 MPa to Obtain a laminate. Next, the layered body was hot-pressed under the conditions of 0.5 MPa and 110°C. The case where no deformation was found in the sealant layer of the laminated body after the hot pressing was evaluated as A, and the case where the area of the sealant layer was enlarged and deformed was evaluated as B.

[Evaluation of Storage Stability of Sealant Layer] Two sealing sheets obtained in Examples and Comparative Examples were prepared, respectively. The sealant layer of one sealing sheet was used as test piece A, and the temperature was raised from 0°C to 200°C at a temperature increase rate of 10°C/min for differential scanning calorimetry (apparatus used: DSC Q2000 manufactured by TA Instruments) , Obtain the peak area [area (α)] of the exothermic peak. The other sealing sheet was stored for 7 days in an environment of 23°C and a relative humidity of 50%, and the sealant layer of this sealing sheet was used as test piece B, and the differential scanning calorimetry was performed in the same manner to obtain The area of the exothermic peak [area (β)]. Those whose ratio of area (β) to area (α) is 95% or more are evaluated as A, and those whose ratio is less than 95% are evaluated as B.

[Table 1]

The following can be known from Table 1. The sealant layer of the sealing sheet obtained in Examples 1 to 3 was excellent in adhesiveness at 23°C and hardly deformed during the thermal curing process. On the other hand, since the sealant layer of the sealing sheet obtained in Comparative Example 1 did not include a thermal cationic polymerization initiator having low-temperature reactivity, it did not satisfy the condition (III) of the present invention. Therefore, it is easy to become fluid during the thermal hardening process, and the shape retention is poor. Furthermore, the sealant layer of the sealing sheet obtained in Comparative Example 2 did not satisfy the condition (II) of the present invention. Therefore, the adhesion at 23°C is poor. In addition, the sealant layer of the sealing sheet obtained in Comparative Example 2 includes a thermal cationic polymerization initiator having low-temperature reactivity, but does not include an epoxy compound having a glycidyl ether group. Therefore, the storage stability of this sealing sheet is poor.

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Claims (12)

A sealing sheet, which is a sealing sheet including a thermosetting sealant layer, and is characterized by satisfying the following conditions (I), (II) and (III), condition (I): the aforementioned sealant layer contains One or more epoxy compounds, condition (II): the storage modulus of the aforementioned sealant layer at 23°C is 1.3×10 ⁷ Pa or less, and condition (III): when the aforementioned sealant layer is at 25°C/ When the temperature was increased from 35°C to 110°C and maintained at 110°C at a minute rate, the complex viscosity of the sealant layer after 250 seconds from the start of the temperature rise was 1×10 ⁴ Pa·s or more. The sealing sheet according to claim 1, wherein the aforementioned sealant layer satisfies the following condition (IV), condition (IV): prepare a sealant layer of the same nature [sealant layer (A) and sealant layer (B)] , And using the sealant layer (A) as a test piece, the temperature is raised from 0°C to 200°C at a temperature increase rate of 10°C/min. Differential scanning calorimetry is performed to obtain the exothermic peak area [area (α) ] Next, after storing the sealant layer (B) at 23°C and a relative humidity of 50% for 7 days, it was used as a measurement sample, and the temperature was raised from 0°C to 200°C at a temperature increase rate of 10°C/min. Differential scanning calorimetry is performed to obtain the exothermic peak area [area (β)]. Based on the obtained area value, X calculated by the following formula (1) is 95% or more [number 1]

. The sealing sheet according to claim 1, wherein at least one of the aforementioned epoxy compounds is an epoxy compound that is liquid at 25°C. The sealing sheet according to claim 3, wherein the content of the epoxy compound that is liquid at 25° C. is 55% by mass or more with respect to the entire sealant layer. The sealing sheet according to claim 1, wherein at least one of the aforementioned epoxy compounds includes a glycidyl ether-based epoxy compound. The sealing sheet according to claim 1, wherein at least one type of the aforementioned epoxy compound includes an epoxy compound with an alicyclic skeleton. The sealing sheet according to claim 1, wherein the sealant layer includes a hardener, and at least one type of the hardener is a thermal cationic polymerization initiator. The sealing sheet according to claim 7, wherein a hardening agent including a thermal cationic polymerization initiator whose peak top temperature of the exothermic peak is 120°C or less when the differential scanning calorimetry is measured under the following conditions is used as the hardening agent At least one of (Differential Scanning Calorimetry) A mixture of 0.1 parts by mass of thermal cationic polymerization initiator, 100 parts by mass of bisphenol A diglycidyl ether, and 0.1 parts by mass of γ-butyrolactone was used as the measurement sample, and the temperature was increased from 30 at a rate of 10°C/min. The temperature was raised to 300°C for differential scanning calorimetry. The sealing sheet according to claim 8, wherein a hardening agent that further includes a thermal cationic polymerization initiator whose peak top temperature of the exothermic peak exceeds 120°C when the differential scanning calorimetry is measured under the following conditions is used as the hardening agent At least one of (Differential Scanning Calorimetry) A mixture of 0.1 parts by mass of thermal cationic polymerization initiator, 100 parts by mass of bisphenol A diglycidyl ether, and 0.1 parts by mass of γ-butyrolactone was used as the measurement sample, and the temperature was increased from 30 at a rate of 10°C/min. The temperature was raised to 300°C for differential scanning calorimetry. The sealing sheet according to claim 7, wherein all the aforementioned hardeners are thermal cationic polymerization initiators. The sealing sheet according to claim 1, wherein the sealant layer includes a binder resin, and at least one type of the binder resin is a binder resin having a glass transition temperature (Tg) of 60° C. or higher. The sealing sheet described in claim 1 is used for sealing optical-related devices.