JP2017112020A - Pressure sensitive adhesive sheet and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device preventing irregular reflection of light emitted from, for example, an organic EL device or the like and thereby capable of effectively guiding light to the outside.SOLUTION: The present invention relates to a pressure sensitive adhesive sheet used to bond a transparent member (A) and a light extraction member (B) constituting a light emitting device. The pressure sensitive adhesive sheet has an adhesive layer (C). When the adhesive layer (C) having a longitudinal dimension of 5 cm, a lateral dimension of 2 cm and a thickness dimension of 25 μm is allowed to stand in an environment at 100°C for 30 minutes, an amount of component (x) produced by hydrolysis of the adhesive layer (C) is 30 ppm or less.SELECTED DRAWING: None

Description

  The present invention relates to a pressure-sensitive adhesive sheet that can be used in a manufacturing scene of a light-emitting device that constitutes, for example, a lighting fixture or an information display device including an organic electroluminescence light-emitting device.

  Organic electroluminescence (organic EL) technology has attracted attention as a promising technology for realizing, for example, low power consumption, light weight, and flexibility of lighting fixtures and information display devices.

  As an apparatus using the organic EL technology (organic EL apparatus), for example, it is emitted from an organic EL light emitting device for the purpose of improving light extraction efficiency, preventing reflection of external light, preventing adhesion of fingerprints, and imparting design properties. An apparatus is known in which a functional film is attached to the surface from which the light is emitted to the outside of the device. In general, an adhesive, an adhesive sheet or the like is often used for attaching the functional film.

  As an adhesive sheet that can be used for attaching the functional film, it is known that, for example, an optical adhesive tape containing a specific resin for optical adhesive tape and a crosslinking agent can be used (for example, see Patent Document 1).

  However, when the optical adhesive tape is used for bonding a part of the organic EL light-emitting device and the functional film, fine bubbles are formed in the pressure-sensitive adhesive sheet in the decompression step after the bonding. As a result, the transparency is lowered, and as a result, irregular reflection of the light emitted from the organic EL element is caused, and the light extraction efficiency is sometimes lowered.

JP2015-003960A

  The problem to be solved by the present invention is, for example, excellent in that fine bubbles are not easily formed in the pressure-sensitive adhesive sheet even when a pressure reducing step often performed in manufacturing an organic EL light emitting device is performed. It is to provide an adhesive sheet capable of maintaining transparency.

  The present invention is a pressure-sensitive adhesive sheet used for joining the transparent member (A) constituting the light emitting device and the light extraction member (B), wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer (C), When the test piece obtained by cutting the adhesive layer (C) into a size of 5 cm in length, 2 cm in width and 25 μm in thickness was left to stand in an environment of 100 ° C. for 30 minutes, the test piece was produced by hydrolysis. It is related with the adhesive sheet characterized by the quantity of a component (x) being 30 ppm or less.

  Even if the pressure-sensitive adhesive sheet of the present invention has undergone a decompression step that is often performed when manufacturing an organic EL light-emitting device, for example, it is difficult to form fine bubbles inside the pressure-sensitive adhesive sheet, and has excellent transparency. Since it can be held, it can be suitably used for manufacturing a light-emitting device that can prevent irregular reflection of light emitted from an organic EL device or the like and efficiently guide light to the outside.

  The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet used for joining the transparent member (A) constituting the light emitting device and the light extraction member (B), and the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer (C). Yes, when the test piece obtained by cutting the adhesive layer (C) into a size of 5 cm in length, 2 cm in width and 25 μm in thickness was allowed to stand in an environment of 100 ° C. for 30 minutes, the test piece was hydrolyzed. The amount of the component (x) produced is 30 ppm or less.

  The pressure-sensitive adhesive sheet can effectively suppress the formation of fine bubbles inside the pressure-sensitive adhesive sheet even when the pressure-reducing step often performed when manufacturing the organic EL light-emitting device. As a result, it is possible to suppress a decrease in the transparency of the pressure-sensitive adhesive sheet due to the pressure reduction step.

  Here, as the pressure-sensitive adhesive sheet, when the pressure-sensitive adhesive sheet subjected to heat treatment under reduced pressure at 70 ° C. to 100 ° C. and 10 Pa to 100 Pa is visually observed, no bubbles are observed, or the diameter is about 10 μm to 20 μm. It is possible to maintain excellent transparency by using a material that can be observed only slightly, prevent irregular reflection of light emitted from an organic EL device, etc., and efficiently guide light to the outside. It is preferable when used for manufacturing a light emitting device.

  The pressure-sensitive adhesive sheet is a so-called base composed of a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (C) on one side or both sides of a base material directly or via another layer, or a single-layer or multi-layer pressure-sensitive adhesive layer (C). Material-less pressure-sensitive adhesive sheets can be used, and the use of the base-material-less pressure-sensitive adhesive sheet is excellent in light transmission, prevents irregular reflection of light emitted from organic EL devices, etc., and efficiently This is preferable because a light emitting device capable of guiding light to the outside can be manufactured.

  The pressure-sensitive adhesive sheet preferably has a thickness of 10 μm to 50 μm, and the use of a thickness of 15 μm to 25 μm suppresses the generation of bubbles, and the organic EL light emitting device It is more preferable for contributing to the reduction in thickness.

  The pressure-sensitive adhesive layer (C) constituting the pressure-sensitive adhesive sheet of the present invention is a layer provided directly or via another layer between the transparent member (A) constituting the light-emitting device and the light extraction member (B). is there.

  As the adhesive layer (C) constituting the adhesive sheet, when the adhesive layer (C) having a size of 5 cm in length, 2 cm in width and 25 μm in thickness is allowed to stand for 30 minutes in an environment of normal pressure and 100 ° C. In addition, the component (x) produced by hydrolysis of the adhesive layer (C) is used in an amount of 30 ppm or less. By using the said adhesion layer (C), when passing through the said pressure reduction process, it can prevent effectively that a fine bubble is formed.

  The amount of the component (x) is preferably 20 ppm or less, more preferably 10 ppm or less, and 5 ppm or less can effectively prevent the formation of fine bubbles, and as a result. In view of suppressing the decrease in the transparency of the pressure-sensitive adhesive sheet due to the pressure reduction step, it is particularly preferable.

  As the component (x), for example, when an acrylic adhesive layer is used as the adhesive layer (C), an alcohol produced by hydrolysis of a part of the acrylic polymer used in the structure is used. Can be mentioned.

  For example, if the (meth) acrylic acid alkyl ester is used in the production of an acrylic polymer, the alcohol is produced by hydrolysis.

  In particular, when an acid group such as a carboxyl group is present in the acrylic adhesive layer, it functions as an acid catalyst. Therefore, the hydrolysis of the (meth) acrylic acid alkyl ester is promoted, and the alcohol that causes the bubbles is reduced. It becomes easy to generate. Therefore, the content of the acid group is preferably 1% by mass or less in the adhesive layer (C), and more preferably not present at all.

  As the adhesive layer (C), for example, an acrylic adhesive layer, a urethane adhesive layer or a silicone adhesive layer can be used, and an acrylic adhesive layer is preferably used.

  Further, as the adhesive layer (C), in order to prevent the formation of fine bubbles when the decompression step is performed, a layer having a small proportion of acid groups such as carboxyl groups and sulfonic acid groups is used. It is preferable to use one having an acid value of 3.3 mgKOH / g or less.

  As the composition (c) that can be used for forming the adhesive layer (C), for example, a composition containing an acrylic polymer, a urethane resin, a silicone resin, or the like can be used. Among these, as the composition (c), it is preferable to use a composition containing an acrylic polymer in order to achieve both excellent adhesion reliability and low cost.

  The acrylic polymer can be produced by polymerizing various monomers. As the monomer, for example, (meth) acrylic acid alkyl ester can be used.

  Examples of the (meth) acrylic acid alkyl ester include (meth) acrylate methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, Cyclohexyl acrylate, n-octyl acrylate, isooctyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, isodecyl acrylate, lauryl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, t-butyl methacrylate, n-hexy Alkyl groups having 1 to 12 carbon atoms such as methacrylate, cyclohexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, lauryl methacrylate, hydroxyethyl acrylate, 2-methoxyethyl acrylate (Meth) acrylates having the following can be used:

  As the (meth) acrylate having an alkyl group having 1 to 12 carbon atoms, it is preferable to use at least one of n-butyl acrylate, 2-ethylhexyl methacrylate, and 2-methoxyethyl acrylate.

  The (meth) acrylate having an alkyl group having 1 to 12 carbon atoms may be used in the range of 50% by mass to 100% by mass with respect to the total amount of monomers used for the production of the acrylic polymer. Preferably, it is more preferable to use it in the range of 65% by mass to 95% by mass because the adhesion and cohesion can be improved and the generation of bubbles at the interface can be prevented.

  As said acrylic polymer, what has functional groups, such as a hydroxyl group and an amino group, can be used. At that time, a vinyl monomer having a functional group such as a hydroxyl group or an amino group can be used as the monomer used in the production of the acrylate copolymer.

  Examples of the vinyl monomer having a functional group such as a hydroxyl group or an amino group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and dimethyl. Aminoethyl acrylamide, N-vinyl pyrrolidone, acrylonitrile, N-vinyl caprolactam, acrylamide, styrene, vinyl acetate, N-methylol acrylamide, glycidyl methacrylate and the like can be used alone or in combination of two or more. Of those described above, it is preferable to use 2-hydroxyethyl (meth) acrylate because the adhesion and cohesion can be improved.

  The total amount of the vinyl monomer having a functional group such as a hydroxyl group or an amino group is used in the range of 0.1% by mass to 40% by mass with respect to the total amount of monomers used for the production of the acrylic polymer. It is preferable.

  As the monomer, a monomer having a carboxyl group such as (meth) acrylic acid may be used as long as the acid value of the adhesive layer (C) is within the above range. It is preferably in the range of 1% by mass or less, more preferably in the range of 0.5% by mass, and 0% by mass based on the total amount of the monomers. ) And the formation of fine bubbles in the pressure-sensitive adhesive sheet is particularly preferable.

  The acrylic polymer can be produced, for example, by polymerizing the monomer by a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, an ultraviolet irradiation method, or an electron beam irradiation method.

  As said acrylic polymer, the weight average molecular weight measured by standard polystyrene conversion measured by a gel permeation chromatograph (GPC) (gel permeation chromatography, SC-8020 by Tosoh Corporation, high molecular weight column TSKgelGMHHR-H) , Solvent: tetrahydrofuran) is preferably 100,000 to 2,000,000, particularly preferably 400,000 to 1,500,000. By using an acrylic polymer having a weight average molecular weight in the above range, it is easy to increase the cohesive force of the adhesive layer (C) in a high temperature environment, and to suppress the formation of fine bubbles in the adhesive sheet. Is particularly preferable.

  Moreover, when forming the said adhesion layer (C), the composition containing a crosslinking agent with the said acrylic polymer etc. can be used.

  As the crosslinking agent, for example, an isocyanate crosslinking agent, an epoxy crosslinking agent, a chelate crosslinking agent, an aziridine crosslinking agent, or the like can be used, and an epoxy crosslinking agent or an isocyanate crosslinking agent is preferably used. .

  The crosslinking agent is preferably used in an amount of 0.05% by mass to 15% by mass, more preferably 0.1% by mass to 10% by mass with respect to the total amount of the adhesive layer (C). The use of 15% by mass to 5% by mass is more preferable for obtaining an adhesive layer (C) having a gel fraction described later.

  As said adhesion layer (C), it is preferable to use what a gel fraction is 50 mass%-90 mass%, and it is what uses that it is 60 mass%-85 mass%. ) Because it is easy to increase the cohesive force in a high temperature environment.

  The gel fraction is expressed as a percentage of the original mass by immersing the cured pressure-sensitive adhesive layer in toluene, measuring the mass after drying of the insoluble matter remaining after standing for 24 hours. Gel fraction = [(mass after adhesion layer is immersed in toluene) / (mass before adhesion layer is immersed in toluene)] × 100

  The thickness of the pressure-sensitive adhesive layer (C) is preferably thin in a range that does not impair the adhesiveness, from the viewpoint of reducing foaming and residual solvent in the coating and drying process, and is in the range of 10 μm to 55 μm. Is more preferable, and it is further more preferable that they are 15 micrometers-30 micrometers.

  Further, the haze of the pressure-sensitive adhesive layer (C) is preferably 1.5% or less, and more preferably 1% or less.

  The adhesive strength of the pressure-sensitive adhesive layer (C) of the present invention is as follows. The pressure-sensitive adhesive layer (C) is placed under a temperature of 23 ° C. and a relative humidity of 50% RH using a 2 kg roller against a clean and smooth glass plate. The adhesive force is preferably 5 N / 25 mm or more, and preferably 7 N / 25 mm to 12 N / 25 mm at a peeling speed of 300 mm / min after pressing once in one reciprocation and allowing to stand for 1 hour. In addition, it is excellent in adhesion to the transparent member (A) and the light extraction member (B), and is more preferable for suppressing the formation of fine bubbles in the pressure-sensitive adhesive sheet.

The pressure-sensitive adhesive layer (C) preferably has a storage elastic modulus G ′ measured at 1 Hz and 100 ° C. of 5.0 × 10 ⁴ Pa or more, and 6.0 × 10 ⁴ Pa to 2.0 ×. It is more preferable to use the one in the range of 10 ⁵ Pa from the viewpoint of suppressing the formation of fine bubbles in the pressure-sensitive adhesive sheet because the pressure-sensitive adhesive layer (C) has excellent cohesive force in a high temperature environment.

  The storage elastic modulus G ′ at 100 ° C. was measured using a viscoelasticity testing machine (trade name: ARES-G2 manufactured by TA Instruments Japan Co., Ltd.). It can be obtained by sandwiching a test piece in between and measuring the storage elastic modulus and loss elastic modulus at a temperature of 80 ° C. and a frequency of 1 Hz. In addition, as a test piece used by the said measurement, what cut | judged the said adhesion layer (C) in the circular shape which consists of a 1 mm thickness and a diameter of 8 mm is used.

  The Asker C hardness of the pressure-sensitive adhesive layer (C) is preferably 70 or less at 23 ° C., more preferably 20 to 60, and more preferably 20 to 55, the high temperature environment of the pressure-sensitive adhesive layer (C). It is more preferable because it is excellent in cohesion force below, can suppress the formation of fine bubbles in the pressure-sensitive adhesive sheet, can further impart flexibility to the organic EL device, and can be easily molded into a curved shape.

(Transparent member constituting light emitting device (A))
The pressure-sensitive adhesive sheet of the present invention can be suitably used for adhesion between the transparent member (A) and the light extraction member (B) that exclusively constitute the light-emitting device.

  Examples of the light emitting device include an organic electroluminescence light emitting device (organic EL light emitting device), a liquid crystal display device including a backlight unit, and the like, and an organic EL light emitting device is preferably used.

  Examples of the organic EL light emitting device include those having a structure in which an organic light emitting medium layer is sandwiched between an anode layer and a cathode layer. The organic light emitting medium layer emits light by applying a voltage between both electrodes and passing a current.

  As a more specific structure of the organic EL light emitting device, for example, a structure in which a base material / anode layer / organic light emitting medium layer / cathode layer / base material layer are laminated in order is given. The organic light emitting medium layer / cathode layer / protective layer / adhesive layer / base material and the like are preferably laminated in this order.

  Of the surface of the light emitting device, a member that transmits light when light is emitted from the light emitting device to the outside, and that is configured to have a surface on which the light extraction member (B) is provided via the adhesive layer (C). Examples of the transparent member (A) that can be used include those corresponding to one or both of the above-mentioned substrates.

  Examples of the base material include glass base materials and plastic base materials such as polycarbonate, polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, cycloolefin polymer, polycarbonate, polyethersulfone, polypropylene, polyethylene, polyarylate, polyamide, and the like. It is also possible to use a material in which an electrode layer such as an anode layer or a cathode layer is provided on a part of its surface.

  Although the thickness of the said transparent member (A) can be suitably selected in consideration of flexibility, light transmittance, designability, etc., it is preferably 10 μm to 200 μm, more preferably 20 μm to 105 μm.

  In addition, as the light emitting device, a device having the protective layer can be used for the purpose of preventing deterioration due to the influence of moisture.

  As the protective layer, for example, a moisture sealing member can be used, and as the moisture sealing member, for example, silicon nitride, silicon oxide, ceramics, etc. excellent in gas barrier properties can be used. Moreover, when providing the said moisture sealing member, the technique which forms a thin film with a high-density plasma film-forming method etc. can be used.

(Light extraction member (B))
As said light extraction member (B), what can improve light extraction efficiency by reducing attenuation | damping of the light emitted from the organic EL device etc. can be used, for example.

  Examples of the light extraction member (B) include polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, cycloolefin polymer, polycarbonate, polyethersulfone, polypropylene, polyarylate, polyamide and other plastic films, glass, quartz, and the like. A film or sheet can be used.

  As the plastic film, it is preferable to use a film containing as little as possible a low molecular compound having a weight average molecular weight of 1000 or less, and the content of the low molecular compound relative to the mass of the plastic film is 0.5% by mass or less. It is more preferable to use one.

  If a polyethylene terephthalate film is used as the plastic film, the polyethylene terephthalate film has a cyclic trimer content composed of ethylene glycol and terephthalic acid of 0.4% by mass or less based on the mass. It is preferable to use a material having a content of 0.3% by mass or less in the reduced pressure or heating step when producing the light emitting device of the present invention (B ) Is suppressed, and as a result, a light emitting device with high light extraction efficiency can be manufactured.

  As the light extraction member (B), for the purpose of improving light extraction efficiency, preventing reflection of external light, preventing adhesion of fingerprints, imparting design properties, etc., coating on a part or all of one surface or both surfaces thereof, You may use what gave processes, such as printing, vapor deposition, sputtering, uneven | corrugated processing.

  The thickness of the light extraction member (B) can be appropriately selected in consideration of flexibility, light transmittance, designability, etc., preferably 10 μm to 200 μm, more preferably 20 μm to 105 μm, and still more preferably 30 μm to 55 μm. is there.

(Method for manufacturing light emitting device)
If the case where the light-emitting device of this invention manufactures an organic EL light-emitting device is mentioned as an example, the said transparent member (A) and light extraction member (B) will be bonded through the adhesive sheet which has an adhesion layer (C). It can manufacture by passing through the process of decompressing and heating after passing through the process of combining.

  At that time, the transparent member (A) may already constitute a part of the organic EL light emitting device or the like, and the light extraction member (B) via the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (C). After being pasted together, it may be pasted on a part of the light emitting device.

  As the pressure-sensitive adhesive layer (C), it is preferable to use the base material-less pressure-sensitive adhesive sheet using the pressure-sensitive adhesive sheet and constituted by a single-layer or multilayer pressure-sensitive adhesive layer (C).

  Specifically, the organic EL light-emitting device of the present invention can be produced by the following method.

  First, the composition (c) capable of forming the adhesive layer (C) is applied to the release treatment surface of the release film (1), and after the treatment such as drying is performed, the release is performed. A substrate-less pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer (C) is produced by pasting the film (2) on the release treatment surface.

  Next, after sticking the pressure-sensitive adhesive sheet to one member of the transparent member (A) or the light extraction member (B), the other member (transparent member (A) or light extraction member (B)) is pasted. .

  Next, the member which bonded the said transparent member (A) and the light extraction member (B) through the said adhesive sheet is processed in the process of pressure reduction and pressurization. The process may be performed particularly when a light emitting device including an organic EL light emitting device is manufactured. In the conventional pressure-sensitive adhesive sheet, fine bubbles are formed in the inside thereof, and as a result, there has been a concern about causing irregular reflection of light and the like.

  However, in the production of the light-emitting device of the present invention, by using the pressure-sensitive adhesive sheet provided with the specific pressure-sensitive adhesive layer (C), for example, bubbles having an average bubble diameter exceeding 10 μm cannot be formed. Irregular reflection of light and the like can be minimized.

  The decompression step may be performed under severe decompression conditions, for example, 100 Pa or less, and further 20 Pa or less. Even when the pressure-sensitive adhesive layer (C) constituting the light-emitting device of the present invention is placed under the severe pressure reduction conditions, for example, it does not form bubbles with an average bubble diameter exceeding 10 μm, and as a result, Irregular reflection of light and the like can be minimized.

  Moreover, the said pressure reduction process may be performed with a heating. In this case, the heating may be performed under severe conditions such as 50 ° C. or higher, or 70 ° C. to 150 ° C. The pressure-sensitive adhesive layer (C) constituting the device of the present invention does not form bubbles with an average bubble diameter exceeding 10 μm, for example, even when subjected to the severe pressure reduction and heating conditions. Further, irregular reflection of light and the like can be suppressed to a minimum.

  Moreover, you may use the said plastic base material which can be used as said light extraction member (B) instead of any one of the said release film (1) or (2). Specifically, the adhesive layer (C) is formed on the surface of the light extraction member (B) by applying the composition (c) and drying, and the transparent member (A) is formed on the surface. It is possible to manufacture the light-emitting device of the present invention by applying ultraviolet light, heating, or the like, or the interface between the transparent member (A) or the light extraction member (B) and the adhesive layer (C), or the adhesive. It is preferable for obtaining a light emitting device in which bubbles are prevented from remaining in the layer (C).

  Among the light emitting devices, an organic electroluminescence light emitting device (organic EL light emitting device) can also be produced by the same method as described above. Specifically, the organic EL light emitting device is subjected to a step of bonding the transparent member (A) and the light extraction member (B) constituting the surface of the organic EL light emitting device through the adhesive layer (C), and then reducing the pressure. And it can manufacture by passing through the process of heating.

  The light emitting device of the present invention obtained by the above method can be suitably used for an information display device such as a lighting fixture or a display.

  The light-emitting device of the present invention emits light of various color tones such as luminescent color, white color, and lamp color according to the living environment by using, for example, a member capable of controlling the color tone of light as the light extraction member (B). It can be used suitably as a lighting fixture that can be used.

<Preparation Example 1>
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 70 parts by mass of 2-ethylhexyl acrylate, 30 parts by mass of 2-hydroxyethyl acrylate, and 2, After dissolving 0.2 parts by mass of 2′-azobisisobutylnitrile in 100 parts by mass of ethyl acetate and replacing the inside of the reaction vessel with nitrogen, they were polymerized at 80 ° C. for 8 hours to give a weight average molecular weight of 700,000. An acrylic polymer (A1) solution was obtained.

  Next, the acrylic polymer (A1) solution and ethyl acetate are mixed to adjust the nonvolatile content thereof, whereby the pressure-sensitive adhesive composition (a) having a nonvolatile content of 30% by mass of the acrylic polymer (A1). Got.

<Preparation Example 2>
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 65 parts by mass of n-butyl acrylate, 30 parts by mass of methyl acrylate, and 5 parts by mass of 2-hydroxyethyl acrylate And 0.2 part by mass of 2,2′-azobisisobutylnitrile as a polymerization initiator are dissolved in 100 parts by mass of ethyl acetate, and the inside of the reaction vessel is purged with nitrogen, and then they are polymerized at 80 ° C. for 8 hours. As a result, an acrylic polymer (A2) solution having a weight average molecular weight of 700,000 was obtained.

  Next, the pressure-sensitive adhesive composition (b) having a nonvolatile content of 30% by mass by mixing the acrylic polymer (A2) solution and ethyl acetate and adjusting the nonvolatile content of the acrylic polymer (A2). Got.

<Preparation Example 3>
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 75 parts by mass of 2-methoxyethyl acrylate, 24 parts by mass of n-butyl acrylate, and 2-hydroxyethyl acrylate 1 part by mass and 0.2 part by mass of 2,2′-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts by mass of ethyl acetate, and the inside of the reaction vessel was purged with nitrogen. The acrylic polymer (A3) solution with a weight average molecular weight of 700,000 was obtained by carrying out time polymerization.

  Next, the pressure-sensitive adhesive composition (c) in which the nonvolatile content of the acrylic polymer (A3) is 30% by mass by mixing the acrylic polymer (A3) solution and ethyl acetate and adjusting the nonvolatile content thereof. Got.

<Preparation Example 4>
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 95 parts by mass of n-butyl acrylate, 4 parts by mass of acrylic acid, and 1 part by mass of 2-hydroxyethyl acrylate Then, 0.2 parts by mass of 2,2′-azobisisobutylnitrile as a polymerization initiator is dissolved in 100 parts by mass of ethyl acetate, the inside of the reaction vessel is purged with nitrogen, and then they are polymerized at 80 ° C. for 8 hours. As a result, an acrylic polymer (A4) solution having a weight average molecular weight of 700,000 was obtained.

  Next, the pressure-sensitive adhesive composition (d) in which the acrylic polymer (A4) has a nonvolatile content of 30% by mass by mixing the acrylic polymer (A4) solution and ethyl acetate and adjusting the nonvolatile content thereof. Got.

Example 1
What mixed 100 mass parts of the said adhesive composition (a) and 0.2 mass parts of isocyanate type crosslinking agents (The Nippon Polyurethane Industry Co., Ltd. make, Coronate HX, solid content 75 mass%), and stirred for 15 minutes. , Coated on the surface of a 50 μm thick polyester film (hereinafter “# 50 release film”), one side of which was peeled off with a silicone compound, so that the thickness after drying was 25 μm, and dried at 75 ° C. for 5 minutes. By doing so, an adhesive sheet was obtained.

  A 38 μm thick polyester film (hereinafter referred to as “# 38 release film”), one side of which was peeled off with a silicone compound, was bonded to the surface of the adhesive film, and cured at 23 ° C. for 7 days. A baseless pressure-sensitive adhesive sheet having a fraction of 80% by mass was obtained.

(Example 2)
What mixed 100 mass parts of said adhesive compositions (b) and 0.3 mass part of isocyanate type crosslinking agent (Nippon Polyurethane Industry Co., Ltd. coronate HX, solid content 75 mass%), and stirred for 15 minutes, It is coated on the surface of a 50 μm-thick polyester film (hereinafter “# 50 release film”) whose one side has been peeled off with a silicone compound so that the thickness after drying is 25 μm, and is dried at 75 ° C. for 5 minutes. Thus, an adhesive sheet was obtained.

  A 38 μm thick polyester film (hereinafter referred to as “# 38 release film”), one side of which was peeled off with a silicone compound, was bonded to the surface of the adhesive film, and cured at 23 ° C. for 7 days. A substrate-less pressure-sensitive adhesive sheet having a fraction of 75% by mass was obtained.

(Example 3)
What mixed 100 mass parts of said adhesive compositions (c) and 0.4 mass part of isocyanate type crosslinking agent (Nippon Polyurethane Industry Co., Ltd. coronate HX, solid content 75 mass%), and stirred for 15 minutes, It is coated on the surface of a 50 μm-thick polyester film (hereinafter “# 50 release film”) whose one side has been peeled off with a silicone compound so that the thickness after drying is 25 μm, and is dried at 75 ° C. for 5 minutes. Thus, an adhesive sheet was obtained.

  A 38 μm thick polyester film (hereinafter “# 38 release film”), one side of which was peeled off with a silicone compound, was bonded to the surface of the pressure-sensitive adhesive film, and aged for 7 days at 23 ° C. A substrate-less pressure-sensitive adhesive sheet having a fraction of 75% by mass was obtained.

(Comparative Example 1)
100 parts by mass of the pressure-sensitive adhesive composition (d) and 0.6 parts by mass of an isocyanate-based cross-linking agent (Nihon Polyurethane Industry Co., Ltd. Coronate L-45, solid content: 45% by mass) were mixed and stirred for 15 minutes. Is applied to the surface of a 50 μm thick polyester film (hereinafter “# 50 release film”), one side of which has been peeled off with a silicone compound, so that the thickness after drying is 25 μm, at 75 ° C. for 5 minutes. An adhesive sheet was obtained by drying.

  A 38 μm thick polyester film (hereinafter “# 38 release film”), one side of which was peeled off with a silicone compound, was bonded to the surface of the pressure-sensitive adhesive film, and aged for 7 days at 23 ° C. A substrate-less pressure-sensitive adhesive sheet having a fraction of 75% by mass was obtained (mass ratio of carboxyl group in the pressure-sensitive adhesive layer was 8.5% by mass).

(Measurement of components produced by hydrolysis)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were allowed to stand for 1 week in an environment of 60 ° C. and 90% RH, and cut into a size of 5 cm in length and 2 cm in width to obtain a test piece.

  The test piece was put into a vial bottle with a capacity of 50 cc, purged with nitrogen and then capped, and left in an environment of 100 ° C. for 30 minutes.

  After the standing, 1 cc of the gas present in the vial is collected using a syringe, and the total weight of the gas components is measured by gas chromatography (GC-14B manufactured by Shimadzu Corporation). The amount of component (x) per unit volume was calculated.

(Foaming test)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were allowed to stand in an environment of 60 ° C. and 90% RH for 1 week, and then a polyethylene terephthalate film (A4300-38, manufactured by Toyobo Co., Ltd.) was bonded to both sides. The test piece was left for 1 hour under% RH.

  After the test piece was left at 20 Pa and 100 ° C. for 1 hour, the presence or absence of bubbles was observed with a magnifying microscope (magnification 100 times).

  ◯: There were no bubbles at all, or there were no bubbles having a diameter of 20 μm or less, and the film had good transparency.

  X: Bubbles having a diameter of more than 20 μm were confirmed, and a significant decrease in transparency was confirmed as compared to before leaving.

(Transparency evaluation)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were allowed to stand in a 60 ° C. and 90% RH environment for 1 week, and then bonded to glass plates (Float plate glass manufactured by Nippon Sheet Glass Co., Ltd., length 5 cm, width 4 cm) on both sides. The test piece was left for 1 hour at 23 ° C. and 50% RH.

  The test piece was left at 20 Pa and 100 ° C. for 1 hour, and then the haze was measured according to JIS K7136: 2000.

  ○: Haze was 1.5% or less.

  X: Haze exceeded 1.5%.

Claims (6)

A pressure-sensitive adhesive sheet used for joining a transparent member (A) constituting a light emitting device and a light extraction member (B), wherein the pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer (C), and the pressure-sensitive adhesive layer (C ) Was cut into a size of 5 cm in length, 2 cm in width and 25 μm in thickness, and the component (x) produced by hydrolysis of the test piece was allowed to stand in an environment of 100 ° C. for 30 minutes. The pressure-sensitive adhesive sheet is characterized by having an amount of 30 ppm or less. The pressure-sensitive adhesive sheet according to claim 1, wherein the component (x) is alcohol. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer (C) is an acrylic pressure-sensitive adhesive layer, and a mass ratio of a carboxyl group to a mass of the acrylic pressure-sensitive adhesive layer is 1% by mass or less. The transparent member (A) is a member that transmits light when light is emitted from the light emitting device to the outside, and is a glass substrate or a plastic substrate having an electrode layer. The pressure-sensitive adhesive sheet according to item. The pressure-sensitive adhesive sheet according to claim 1, wherein the light-emitting device is an organic electroluminescence light-emitting device. It is a light-emitting device which has an adhesion layer (C) between the transparent member (A) which comprises the surface of a light-emitting device, and a light extraction member (B), Comprising: The said adhesion layer (C) is Claims 1-5. It is a layer comprised by the adhesive sheet of any one of these, The light-emitting device characterized by the above-mentioned.