JP2016204552A - Adhesive sheet, surface protective member and electronic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double-sided adhesive sheet achieving excellent reworkability and air release characteristics and also excellent edge lift property.SOLUTION: The invention relates to an adhesive sheet having a silicone-based adhesive layer (A) on at least one side of a substrate, where the silicone-based adhesive layer (A) contains a silicone-based polymer (a1) and a silicone-based tackifier resin (a2) of 70 mass% or more based on the total amount of the silicone polymer (a1).SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adhesive sheet suitable for bonding, for example, an information display part of a display and a member made of glass or the like.

  Conventionally, an information display unit of a display mounted on an electronic device has a hard coat layer with a pencil hardness of about 2H on one side of the tempered glass for the purpose of preventing scratches on the surface, and the other side. In many cases, a surface protective member having a pressure-sensitive adhesive layer is attached to the surface.

  The surface protection member usually has a characteristic that can be re-applied after a certain period of time from the initial application and pasting so as to easily correct misalignment or the like caused when it is applied to the surface of the information display unit ( Reworkability) is required. Therefore, the excellent rework property is calculated | required also at the adhesive sheet used for the manufacture.

  Moreover, in order to improve the production efficiency and yield of the surface protection member, the pressure-sensitive adhesive sheet may be required to have a level of reworkability that can be re-attached to the tempered glass if it is initially applied. is there.

  In addition, when the surface protection member is usually affixed to the surface of the information display unit, it is difficult for air bubbles (air) to be involved in the interface between them, and even if air bubbles are involved, The ability to escape (air escape) is required.

  In particular, when a surface protective member composed of the tempered glass and the double-sided pressure-sensitive adhesive sheet is affixed to the information display unit, the tempered glass is a rigid body, so that it cannot be pressure-bonded using a roller or the like. In some cases, bubbles cannot be removed sufficiently and quickly from the interface between the double-sided pressure-sensitive adhesive sheet and the information display unit.

  Therefore, even when the surface protection member is simply placed and pasted on the surface of the information display unit without using the roller or the like, it is difficult for bubbles to remain at the interface between them and bubbles remain. However, it is required for the surface protection member to have a property of being quickly removed. And the double-sided adhesive sheet used for manufacture of the surface protection member provided with the said characteristic is also calculated | required by the outstanding air release property.

  Thus, the manufacture of the surface protection member requires the development or selection and use of a double-sided pressure-sensitive adhesive sheet corresponding to the performance required for the surface protection member.

  As the double-sided pressure-sensitive adhesive sheet, for example, at least one of the pressure-sensitive adhesive layers on both sides of the support is made of a silicone pressure-sensitive adhesive, and the pressure-sensitive adhesive layer is treated with a release agent made of a polymer having a fluorine-containing side chain in the siloxane skeleton. There is known a pressure-sensitive adhesive sheet characterized by being temporarily attached (see, for example, Patent Document 1).

  However, Patent Document 1 does not disclose that the pressure-sensitive adhesive sheet is excellent in reworkability and air release property, nor does it disclose that the pressure-sensitive adhesive sheet can be suitably used in applications requiring these characteristics. Moreover, when the surface protection member comprised from the said adhesive sheet and the tempered glass member which has a printing layer is affixed on the surface of the said information display part, the surface of the said information display part, and the adhesive of the said surface protection member In some cases, bubbles (air) are difficult to escape from the interface with the layer and remain easily.

  Further, as the surface protection member, in addition to the rework property and air release property, for example, even when the surface protection member is affixed to a slightly curved display surface (the surface of the information display portion), the end portion of the surface protection film However, there are cases where it is required to be able to suppress floating from the display surface (edge lift resistance). In some cases, the edge lift resistance can be improved to some extent by using, for example, a surface protective member having a strong adhesive layer. However, a surface protective member simply having a strong adhesive layer may not be sufficient in terms of air release and reworkability.

  As described above, a double-sided pressure-sensitive adhesive sheet and a surface protective member that have both the reworkability and air release property and edge lift resistance have not yet been found.

Japanese Patent Laid-Open No. 5-320592

  The problem to be solved by the present invention is to provide a double-sided pressure-sensitive adhesive sheet that achieves both excellent reworkability and air release properties and excellent edge lift resistance.

  The present inventors are pressure-sensitive adhesive sheets having a silicone-based pressure-sensitive adhesive layer (A) on at least one surface side of a substrate, and the silicone-based pressure-sensitive adhesive layer (A) is formed of a silicone polymer (a1) and The pressure-sensitive adhesive sheet containing 70% by mass or more of the silicone-based tackifier resin (a2) with respect to the total amount of the silicone-based polymer (a1) has found that the above problems can be solved. It was.

  Since the pressure-sensitive adhesive sheet of the present invention has both excellent reworkability and air detachability, and excellent edge lift resistance, for example, an information display portion of a curved display, and a member made of glass or resin It can be suitably used for bonding. Moreover, the adhesive sheet of this invention can be used for manufacture of the surface protection member stuck on the information display part of the said display.

It is a conceptual diagram which shows an example of a structure of the surface protection member of this invention. It is a conceptual diagram showing the evaluation method of edge lift resistance.

  The pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet having a silicone-based pressure-sensitive adhesive layer (A) on at least one surface side of a substrate, and the silicone-based pressure-sensitive adhesive layer (A) is a silicone-based polymer (a1). And 70 mass% or more of the silicone-based tackifier resin (a2) with respect to the total amount of the silicone-based polymer (a1).

  As a specific embodiment of the pressure-sensitive adhesive sheet of the present invention, the one-sided pressure-sensitive adhesive sheet having the silicone pressure-sensitive adhesive layer (A) on one surface side of the base material directly or via another layer, The double-sided pressure-sensitive adhesive sheet having the silicone-based pressure-sensitive adhesive layer (A) directly on the both sides or via another layer, the silicone-based pressure-sensitive adhesive layer (directly or on the other side of the substrate on the one surface side) A double-sided pressure-sensitive adhesive sheet having A) and having a pressure-sensitive adhesive layer other than the silicone-based pressure-sensitive adhesive layer (A) directly or via another layer on the other surface side of the substrate.

[Silicone-based adhesive layer (A)]
The silicone pressure-sensitive adhesive layer (A) constituting the pressure-sensitive adhesive sheet of the present invention can be formed by using a silicone pressure-sensitive adhesive.

  As said silicone type adhesive, what contains a silicone type polymer (a1) and a silicone type tackifying resin (a2) can be used. Moreover, as said silicone type adhesive, what contains a crosslinking agent, a metal catalyst, etc. besides the above-mentioned component can be used.

  As said silicone type polymer (a1), what mainly becomes a binder component of an adhesive can be used, for example, polyorganosilicone etc. can be used.

  As the polyorganosilicone, a peroxide-curing type and an addition-curing type are known, and both can be used. However, the polyorganosilicone exhibits a further excellent rework property and air release property and excellent edge lift resistance. Thus, it is preferable to use an addition-curable polyorganosilicone.

  As the addition-curable polyorganosilicone, for example, polyorganosiloxane having a structure in which a polymerizable unsaturated double bond is bonded to a silicon atom can be used.

  As the addition-curable polyorganosilicone, specifically, those having any of the following structures (1) to (4) can be used, and those having the following structures (1) and (4): Is preferably used.

(R represents a monovalent hydrocarbon group or a hydroxyl group.)

  Specific examples of the addition-curable polyorganosilicone include linear polysiloxanes such as addition-curable dimethylpolysiloxane, addition-curable dimethylphenylpolysiloxane, addition-curable polyethylphenylsiloxane, and addition-curable polymethylphenylsiloxane. Can be used.

  As the addition-curable polyorganosilicone, those having a weight average molecular weight of 150,000 or more are preferably used, those having a weight average molecular weight of 150,000 to 1,000,000 are more preferably used, and 170,000. It is more preferable to use a material having a weight average molecular weight of ˜500,000, and using a material having a weight average molecular weight of 200,000 to 350,000 is particularly preferable for obtaining a pressure-sensitive adhesive sheet having particularly excellent air bleeding properties. preferable.

  The silicone-based tackifier resin (a2) used for forming the silicone-based pressure-sensitive adhesive layer (A) can be appropriately selected from conventionally known ones, but a relatively low molecular weight polyorganosilicone is used. Specifically, it is preferable to use those having a weight average molecular weight of less than 150,000, more preferably 1000 to less than 50,000, and more preferably 1000 to 10,000. Are more preferable, those having 2000 to 8000 are more preferably used, and those having 3000 to 6000 are particularly preferable.

  As the silicone-based tackifying resin (a2), it is more preferable to use an addition-curable polyorganosilicone.

  As the addition-curable polyorganosilicone usable for the silicone-based tackifier resin (a2), for example, one having at least one selected from the group consisting of the structures (1) to (4) is used. It is preferable to use those having the structures (1) and (2). The ratio (molar ratio) between the structure (1) and the structure (2) is preferably structure (1): structure (2) = 0.4: 1 to 1.4: 1, 0.6: It is more preferable to use one that is 1 to 1.2: 1.

  The silicone-based tackifying resin (a2) is used in a range of 70% by mass or more and more preferably in a range of 70% by mass to 100% by mass with respect to the total amount of the silicone-based polymer (a1). , And more preferably in the range of 75% to 90% by mass, since it is possible to achieve both excellent air escape properties and edge lift resistance.

  As said silicone type adhesive, what mixed the said silicone type polymer (a1) and the said silicone type tackifying resin (a2) previously can be used.

  Moreover, as a crosslinking agent which may be contained in the said silicone type adhesive, what has a structure which can react with the functional group which the said silicone type polymer (a1) or the said silicone type tackifying resin (a2) has. For example, those containing a siloxane having a structure (—Si—H) in which at least one of three alkyl groups bonded to a silicon atom is replaced with a hydrogen atom can be used. Specifically, a polyorganohydrodienesiloxane having a structure in which two of three alkyl groups bonded to a silicon atom are replaced with hydrogen atoms can be used. It is preferable to use hydrogen dimethylpolysiloxane having a bonded structure (—Si—H) at both molecular ends.

  Moreover, as a metal catalyst that may be contained in the silicone-based pressure-sensitive adhesive, it is preferable to use, for example, an organometallic catalyst belonging to Group 10 of the periodic table of elements, and specifically, a platinum-based catalyst may be used. It is more preferable because it is excellent in the reaction promoting effect.

  As the crosslinking agent and the catalyst, those previously mixed may be used, or those in which they form a complex may be used. Specifically, it is more preferable to use a complex of platinum (0) and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane or a xylene solution thereof.

  In addition to the above-described components, the silicone-based pressure-sensitive adhesive may contain a solvent such as methyl ethyl ketone or toluene in order to improve application workability.

  As a silicone type adhesive layer (A) formed using the said silicone type adhesive, it is preferable to use that whose gel fraction is 65 mass%-99 mass%, 70 mass%-93 mass. %, More preferably 72% to 85% by weight, for example, excellent reworkability and air bleedability for the information display portion of the display, and excellent edge resistance. It is further preferable for obtaining a pressure-sensitive adhesive sheet having both lift properties.

The gel fraction is applied to one side of a polyester film “A4300 # 38” manufactured by Toyobo Co., Ltd., which is a base material, using a lip coater so that the thickness after drying is 30 μm. Then, after drying at 140 ° C. for 2 minutes, a single-sided adhesive tape is produced by curing at 40 ° C. for 48 hours, and refers to the mass calculated before and after immersing it in toluene and the value calculated by the following equation.
Gel fraction (mass%) = {(mass of silicone-based adhesive layer (A) remaining after immersing single-sided adhesive tape in toluene) / (silicone-based adhesive layer before immersing single-sided adhesive tape in toluene ( A) Mass)} × 100

  Moreover, as said silicone type adhesive layer (A), it is preferable that the total light transmittance (JIS K7361) in the visible light is 90% or more, It is more preferable that it is 92% or more, 93% or more More preferably, some are used.

  Moreover, as said silicone type adhesive layer (A), it is preferable to use that whose haze (JIS K7136) in the visible light is 2% or less, and it is more preferable to use what is 1% or less. Further, it is more preferable to use one that is 0.8% or less.

[Acrylic adhesive layer]
As a specific embodiment of the pressure-sensitive adhesive sheet of the present invention, as described above, the silicone-based pressure-sensitive adhesive layer (A) is provided on one surface side of the base material directly or via another layer, and the base material A double-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer other than the silicone-based pressure-sensitive adhesive layer (A) directly or via another layer on the other surface side of the film. In particular, when the pressure-sensitive adhesive sheet of the present invention is used for the production of a surface protection member for an information display section such as a display, the pressure-sensitive adhesive sheet of the present invention is either directly on one side of the substrate or via another layer. It is preferable to use a double-sided pressure-sensitive adhesive sheet having the silicone pressure-sensitive adhesive layer (A) and having the acrylic pressure-sensitive adhesive layer (B) on the other surface side of the substrate directly or via another layer.

  The acrylic pressure-sensitive adhesive layer (B) can be formed by using an acrylic pressure-sensitive adhesive.

  As said acrylic adhesive, what contains an acrylic polymer (b) and a crosslinking agent, tackifying resin, etc. as needed can be used, for example.

  The acrylic polymer (b) can be produced by polymerizing a monomer containing a (meth) acrylic monomer.

  Examples of the monomer include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, t-butyl acrylate, n-hexyl acrylate, cyclohexyl acrylate, n-octyl acrylate, and isooctyl 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-hexyl methacrylate , Cyclohexyl methacrylate, n-octyl methacrylate, isooctyl meta (Meth) acrylic acid esters having an alkyl group having 2 to 14 carbon atoms such as relate, 2-ethylhexyl methacrylate, isononyl methacrylate, isodecyl methacrylate, lauryl methacrylate, etc. can be used alone or in combination of two or more. .

  Among them, it is preferable to use (meth) acrylic acid alkyl ester having an alkyl group having 4 to 9 carbon atoms as the monomer, and alkyl acrylate having alkyl having 4 to 9 carbon atoms. It is more preferable to use an ester, and the use of n-butyl acrylate and 2-ethylhexyl acrylate can form an acrylic pressure-sensitive adhesive layer (B) having a tensile strength in a suitable range described later, and as a result, It is particularly preferable because it can impart a further excellent reworkability to the member made of glass or resin at the initial stage of application.

  The (meth) acrylic acid ester having an alkyl group having 2 to 14 carbon atoms is in the range of 80% by mass to 99% by mass with respect to the total amount of monomers used for the production of the acrylic polymer (b). It is particularly preferable to use it in the range of 85% by mass to 96% by mass because it is possible to impart even better reworkability to a member made of glass or resin at the initial stage of application.

  Further, as the monomer, in addition to those described above, a monomer having a functional group such as a hydroxyl group, a carboxyl group, or an amino group can be used.

  Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like.

  As the monomer having a carboxyl group, for example, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, crotonic acid, fumaric acid, carboxypropyl acrylate maleate and the like can be used.

  As the monomer having an amino group, for example, dimethylaminoethylacrylamide, N-vinylpyrrolidone, acrylonitrile, N-vinylcaprolactam, acrylamide, styrene, vinyl acetate, N-methylol acrylamide, glycidyl methacrylate and the like can be used. .

  The monomer having a hydroxyl group, a carboxyl group or an amino group should be used in the range of 1% by mass to 20% by mass with respect to the total amount of monomers used for the production of the acrylic polymer (b). It is preferable to use in the range of 4% by mass to 15% by mass.

  Especially, the monomer which has the said hydroxyl group may be used in 0.1 mass%-15 mass% with respect to the whole quantity of the monomer used for manufacture of the said acrylic polymer (b). Preferably, it is more preferably used in the range of 0.1% by mass to 5% by mass.

  The monomer having a carboxyl group may be used in the range of 0.1% by mass to 15% by mass with respect to the total amount of monomers used for the production of the acrylic polymer (b). Preferably, it is more preferably used in the range of 1% by mass to 10% by mass.

  The acrylic polymer (b) can be produced by polymerizing the monomer by a known method such as a solution polymerization method, a bulk polymerization method, a suspension polymerization method, or an emulsion polymerization method. Manufacture by a legal method is desirable for improving the production efficiency of the pressure-sensitive adhesive sheet and reducing the production cost.

  As the acrylic polymer (b) obtained by the above method, it is preferable to use a polymer having a weight average molecular weight in the range of 400,000 to 1,500,000, and a weight average molecular weight in the range of 600,000 to 1,200,000. It is more preferable to use one.

The weight average molecular weight of the acrylic polymer (b) can be measured by gel permeation chromatography (GPC). More specifically, as a GPC measurement device, “SC8020” manufactured by Tosoh Corporation can be used to measure and obtain the following GPC measurement conditions based on polystyrene conversion values.
(GPC measurement conditions)
Sample concentration: 0.5 parts by mass (tetrahydrofuran solution)
Sample injection volume: 100 μL
・ Eluent: Tetrahydrofuran (THF)
・ Flow rate: 1.0 mL / min
Column temperature (measurement temperature): 40 ° C
Column: “TSKgel GMHHR-H” manufactured by Tosoh Corporation
・ Detector: Differential refraction

  As the acrylic pressure-sensitive adhesive that can be used for forming the acrylic pressure-sensitive adhesive layer (B), in addition to the acrylic polymer (b), a material containing a crosslinking agent may be used. It is further preferable when a three-dimensional cross-linked structure is formed in the layer (B) to form an acrylic pressure-sensitive adhesive layer having further excellent reworkability.

  As said acrylic adhesive layer (B), it is preferable to use what the gel fraction is 10 mass%-70 mass%, and using what is 30 mass%-60 mass%, It is preferable because it can impart even better reworkability.

The gel fraction is applied to one side of a polyester film “A4300 # 38” manufactured by Toyobo Co., Ltd., which is a base material, using a lip coater so that the thickness after drying is 30 μm. Then, after drying at 140 ° C. for 2 minutes, a single-sided adhesive tape is produced by curing at 40 ° C. for 48 hours, and refers to the mass calculated before and after immersing it in toluene and the value calculated by the following equation.
Gel fraction (mass%) = {(mass of acrylic pressure-sensitive adhesive layer (B) remaining after immersing single-sided pressure-sensitive adhesive tape in toluene) / (acrylic pressure-sensitive adhesive layer before immersing single-sided pressure-sensitive adhesive tape in toluene ( B) mass)} × 100

  As the crosslinking agent, for example, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, a chelate-based crosslinking agent, an aziridine-based crosslinking agent, or the like may be used as the crosslinking functional group that the acrylic polymer (b) may have. It can be selected and used according to the type, and it is preferable to use an epoxy-based crosslinking agent in order to prevent discoloration (yellowing) of the pressure-sensitive adhesive sheet of the present invention over time.

  The content of the cross-linking agent can be appropriately selected and used so that the acrylic pressure-sensitive adhesive layer (B) having the preferred gel fraction can be formed.

  In order to further improve the adhesive strength of the pressure-sensitive adhesive sheet of the present invention, the acrylic pressure-sensitive adhesive may contain a tackifier resin.

  As the tackifying resin, rosin resin, terpene resin, aliphatic (C5) or aromatic (C9) petroleum resin, styrene resin, phenol resin, xylene resin, methacrylic resin, etc. are used. Among them, it is preferable to use an acrylic tackifying resin in order to form an acrylic pressure-sensitive adhesive layer (B) having further excellent transparency and yellowing resistance.

  As the acrylic tackifying resin, one having a lower molecular weight than that of the acrylic polymer (b) can be used, and an acrylic adhesive that achieves both excellent anti-scattering properties, transparency and yellowing resistance. In forming the agent layer (B), it preferably has a weight average molecular weight of 100 to 100,000, more preferably 1000 to 50,000, and still more preferably 3000 to 30,000. Those having a molecular weight can be used.

  As said acrylic tackifying resin, what is obtained by superposing | polymerizing an acrylic monomer can be used.

  As the acrylic monomer, a (meth) acrylic acid ester having an alkyl group having 1 to 4 carbon atoms is preferably used. Examples of the (meth) acrylic acid ester having an alkyl group having 1 to 4 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n -Butyl (meth) acrylate etc. can be used individually or in combination of 2 or more types.

  Among them, as the (meth) acrylic acid ester having an alkyl group having 1 to 4 carbon atoms, it is preferable to use methyl methacrylate because it can give high adhesion particularly to a member made of glass.

  The (meth) acrylic acid ester having an alkyl group having 1 to 4 carbon atoms is in the range of 80% by mass to 99% by mass with respect to the total amount of monomers used for the production of the acrylic tackifying resin. It is preferable to use it, and it is more preferable to use it in the range of 85% by mass to 96% by mass because high adhesiveness can be imparted to a member made of glass.

  As a monomer used for the production of the acrylic tackifying resin, a monomer having a functional group such as a hydroxyl group, a carboxyl group, or an amino group can be used.

  Examples of the monomer include monomers having a hydroxyl group such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate, acrylic acid, methacrylic acid, and maleic acid. Monomers having a carboxyl group such as acid, maleic anhydride, itaconic acid, crotonic acid, fumaric acid, maleic anhydride carboxypropyl acrylate, dimethylaminoethylacrylamide, N-vinylpyrrolidone, acrylonitrile, N-vinylcaprolactam, acrylamide, Monomers having amino groups such as dimethylaminoethyl (meth) acrylate, styrene, vinyl acetate, N-methylol acrylate, glycidyl methacrylate, etc. can be used alone or in combination of two or more.

  Among them, it is preferable to use a monomer having an amino group because it can be suitably compatible with the acrylic polymer (b) and can form an acrylic pressure-sensitive adhesive layer having excellent optical properties. As the monomer having an amino group, dimethylaminoethyl (meth) acrylate can be preferably used.

  The monomer having a hydroxyl group, a carboxyl group or an amino group should be used in the range of 0.01% by mass to 15% by mass with respect to the total amount of monomers used for the production of the acrylic tackifying resin. Is preferred. In particular, the monomer having an amino group is preferably used in a range of 0.01% by mass to 15% by mass with respect to the total amount of monomers used for the production of the acrylic tackifying resin. It is more preferable to use in the range of 0.1% by mass to 10% by mass.

  The acrylic tackifying resin is preferably used in a range of 5 to 50 parts by mass, and in a range of 7 to 30 parts by mass with respect to 100 parts by mass of the acrylic polymer (b). It is more preferable to use in the range of 9 to 23 parts by mass.

  The acrylic pressure-sensitive adhesive layer (B) has a total light transmittance (JIS K7361) in visible light of preferably 90% or more, more preferably 92% or more, and 92.5% or more. More preferably, some are used.

  Moreover, as said acrylic adhesive layer (B), it is preferable to use the thing whose haze (JIS K7136) in the visible light is 2% or less, and it is more preferable to use what is 1% or less. Further, it is more preferable to use one that is 0.8% or less.

(Base material)
Although it does not specifically limit as a base material which can be used for manufacture of the said adhesive sheet, For example, a polyethylene terephthalate film, a polybutylene terephthalate film, a polyethylene naphthalate film, a polyethylene film, a polypropylene film, a cellophane film, a diacetylcellulose film, a triacetyl Cellulose film, acetylcellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone Film, polyethersulfone film, polyetherimide film, polyimi Film, fluororesin film, nylon film, it is possible to use an acrylic resin film or the like. Among them, it is preferable to use a polyethylene terephthalate film as the substrate, and to use polyethylene terephthalate that has been subjected to easy adhesion treatment, the silicone pressure-sensitive adhesive layer (A) and the acrylic pressure-sensitive adhesive layer (B). It is more preferable for obtaining a pressure-sensitive adhesive sheet having excellent adhesion.

  The substrate preferably has a thickness in the range of 2 μm to 100 μm, more preferably a thickness in the range of 16 μm to 75 μm, and a thickness in the range of 20 μm to 70 μm. It is more preferable to use a material having a thickness in the range of 20 μm to 60 μm.

(Production method)
The pressure-sensitive adhesive sheet of the present invention forms, for example, the silicone pressure-sensitive adhesive layer (A) by applying the silicone pressure-sensitive adhesive to one surface of the base material and drying it. A step of producing a single-sided adhesive tape by applying a release liner to the adhesive layer (A), and applying the acrylic adhesive to a release liner different from the above and drying the acrylic adhesive It is preferable to produce the adhesive layer (B) and the step of transferring the acrylic adhesive layer (B) to the other surface side of the base material constituting the single-sided adhesive tape. It is.

  Examples of the method for applying the silicone-based pressure-sensitive adhesive to a substrate include a method of coating using a precision coating machine such as a lip coater. Drying when forming the silicone-based pressure-sensitive adhesive layer (A) is preferably performed at 110 ° C. to 140 ° C. for 30 seconds to 3 minutes.

  Moreover, as a method of apply | coating the said acrylic adhesive to a release liner etc., the method of coating using precision coating machines, such as a lip coater, is mentioned, for example. Drying when forming the acrylic pressure-sensitive adhesive layer (B) is preferably performed at 80 ° C. to 120 ° C. for 30 seconds to 3 minutes.

  In the pressure-sensitive adhesive sheet of the present invention, a release liner is preferably laminated on the surface of the pressure-sensitive adhesive layer including the silicone-based pressure-sensitive adhesive layer (A).

  As the release liner that may be laminated on the silicone-based pressure-sensitive adhesive layer (A), for example, a resin film such as polyethylene, polypropylene (orientated polypropylene (OPP), cast polypropylene (CPP)), polyethylene terephthalate, or the like is used as it is. be able to.

  On the other hand, as a release liner that may be laminated on the acrylic pressure-sensitive adhesive layer (B), among resin films such as polyethylene, polypropylene (orientated polypropylene (OPP), cast polypropylene (CPP)), polyethylene terephthalate, silicone, etc. What was peel-processed with the system resin etc. can be used.

  The pressure-sensitive adhesive sheet of the present invention preferably has a thickness of 50 μm to 200 μm, and more preferably has a thickness of 60 μm to 150 μm. The thickness is a thickness that does not include the release liner.

  As said silicone type adhesive layer (A) which comprises the adhesive sheet of this invention, a 25-micrometer-thick polyethylene terephthalate film is stuck on the said silicone type adhesive layer, The said polyethylene terephthalate film is made into the said silicone type adhesive layer ( It is preferable to use one having a tensile strength measured by pulling in the direction of 180 ° with respect to the surface of A) in the range of 0.05 N / 25 mm to 0.3 N / 25 mm. By using the silicone-based pressure-sensitive adhesive layer (A) having a tensile strength in the above range, for example, it is possible to further improve reworkability, air escape property, and excellent edge lift resistance with respect to the information display part of the display. It can be compatible.

  The silicone-based pressure-sensitive adhesive layer (A) preferably has a tensile strength in the range of 0.05 N / 25 mm to 0.2 N / 25 mm, preferably 0.07 N / 25 mm to 0.1 N / It is more preferable to use the one having a range of 25 mm because excellent reworkability and air escape property and excellent edge lift resistance can be achieved at a high level.

  In addition, the said tensile strength points out the value measured with the following method. The pressure-sensitive adhesive sheet cut to a width of 50 mm under an environment of 23 ° C. and 50% RH is placed so that the silicone pressure-sensitive adhesive layer (A) is on the upper surface, and the silicone pressure-sensitive adhesive layer (A) is After placing “S-25” (polyester film thickness 25 μm, manufactured by Unitika Co., Ltd.) cut to a width of 25 mm, the upper surface thereof was pressure-applied by reciprocating a 2 kg roller, and then 23 ° C. And left in a 50% RH environment for 1 hour.

  Thereafter, using a tensile tester (Tensilon RTA-100, manufactured by A & D Co., Ltd.) in a 23 ° C. and 50% RH environment, the “S-25” was changed to the silicone-based pressure-sensitive adhesive under the conditions of a tensile speed of 300 mm / min. It is pulled in the direction of 180 ° with respect to the surface of the layer (A), and the adhesive strength when it is peeled is measured. In addition, the said measurement is performed in the state which stuck the acrylic adhesive layer and aluminum plate which comprise the said double-sided adhesive sheet using the double-sided tape "# 8625UJ" by DIC Corporation.

  The silicone pressure-sensitive adhesive layer (A) preferably has a thickness in a range of 15 μm to 50 μm, more preferably in a range of 20 μm to 40 μm, and a thickness in a range of 25 μm to 35 μm. For example, it is particularly preferable when it is possible to achieve both excellent reworkability and air bleedability for an information display portion of a display and the like and impart excellent edge lift resistance.

  Moreover, as an acrylic adhesive layer (B) which the adhesive sheet of this invention may have, a 25-micrometer-thick polyethylene terephthalate film is stuck to the said acrylic adhesive layer (B), The said polyethylene terephthalate film It is preferable to use one having a tensile strength measured by pulling in the direction of 180 ° with respect to the surface of the acrylic pressure-sensitive adhesive layer (B) in the range of 5 N / 25 mm to 28 N / 25 mm. By using an acrylic pressure-sensitive adhesive layer (B) having a tensile strength in the above range, for example, a member made of glass or resin, such as tempered glass, is given more excellent reworkability at the initial stage of application. Can do.

  The acrylic pressure-sensitive adhesive layer (B) preferably has a tensile strength in the range of 10 N / 25 mm to 25 N / 25 mm, and has a range of 13 N / 25 mm to 20 N / 25 mm. For example, it is more preferable because it can impart more excellent reworkability at the initial stage of application to a member made of glass or resin such as tempered glass.

  In addition, the said tensile strength points out the value measured with the following method. The pressure-sensitive adhesive sheet cut to a width of 50 mm under an environment of 23 ° C. and 50% RH is placed so that the acrylic pressure-sensitive adhesive layer (B) is on the upper surface, and the acrylic pressure-sensitive adhesive layer (B). After placing “S-25” (polyester film thickness 25 μm, manufactured by Unitika Co., Ltd.) cut to a width of 25 mm, the upper surface thereof was pressure-applied by reciprocating a 2 kg roller, and then 23 ° C. And left in a 50% RH environment for 1 hour.

  Thereafter, using a tensile tester (Tensilon RTA-100, manufactured by A & D) at 23 ° C. and 50% RH, the “S-25” was converted to the acrylic pressure-sensitive adhesive under the conditions of a tensile speed of 300 mm / min. It is pulled in the direction of 180 ° with respect to the surface of the layer (B), and the adhesive strength when it is peeled is measured. In addition, the said measurement is performed in the state which stuck the silicone type adhesive layer and aluminum plate which comprise the said adhesive sheet using the double-sided tape "# 8625HPW" by DIC Corporation.

  The acrylic pressure-sensitive adhesive layer (B) preferably has a thickness in the range of 10 μm to 50 μm, more preferably in the range of 15 μm to 30 μm, and a thickness in the range of 15 μm to 25 μm. For example, it is particularly preferable for a member made of glass or resin such as tempered glass, since the reworkability and the scattering prevention property which are more excellent in the initial stage of application can be highly compatible. Moreover, when manufacturing the surface protection member by adopting the acrylic pressure-sensitive adhesive layer (B) having the above thickness, the member made of glass or resin such as tempered glass and the acrylic pressure-sensitive adhesive layer (B) It is possible to make it difficult for air bubbles to be caught in the interface.

  The pressure-sensitive adhesive sheet of the present invention can be used exclusively for adhesion between an information display portion of a display and a member made of glass or resin. At that time, the silicone pressure-sensitive adhesive layer (A) constituting the pressure-sensitive adhesive sheet is affixed to the surface of the information display unit, and the acrylic pressure-sensitive adhesive layer (B) is a surface of a member made of glass or resin. It is preferable to affix to the surface in order to maintain excellent reworkability and air release properties.

(Information display part of the display)
The information display unit refers exclusively to a part capable of displaying images, videos, and the like, and examples thereof include the surface of a liquid crystal panel and the surface of an organic EL panel. The outermost surface of the information display unit (the surface to which the silicone-based pressure-sensitive adhesive layer (A) of the pressure-sensitive adhesive sheet is attached) may be a surface made of resin or a surface made of glass. Such a surface is preferable because it is excellent in reworkability with the silicone-based pressure-sensitive adhesive layer (A), air release property, and impact resistance.

(Member made of glass or resin)
Examples of the member include tempered glass.

  The tempered glass is a glass having a strength higher than that of a normal plate glass in which a compressive stress layer is provided on the glass surface. The tempered glass includes physically tempered glass and chemically tempered glass, but it is preferable to use chemically tempered glass.

  Specifically, chemically strengthened glass is glass in which alkali ions having a large ion radius are introduced into the surface of the glass by ion exchange at a temperature lower than the melting point of the glass. Commercial products include Corning Gorilla Glass.

  As the member made of glass such as the tempered glass, it is preferable to use a member having a thickness of 0.1 mm to 0.6 mm. If it is used for surface protection of a mobile device, 0.2 mm to 0.00 mm. It is more preferable to use a thickness of 5 mm.

  As the member made of glass such as the tempered glass, a member having a surface hardness of 5H or more is preferably used, and a member having 9H or more is more preferably used.

  Moreover, as a member consisting of resin, the film or sheet-like thing which consists of resin, such as polyester, such as polyethylene terephthalate, and polyurethane, can be used, for example.

(Surface protection member)
Examples of the surface protecting member include those having a configuration in which a member made of the glass or resin is previously attached to the surface of the acrylic pressure-sensitive adhesive layer (B) of the pressure-sensitive adhesive sheet. Bonding of the pressure-sensitive adhesive sheet and a member made of glass or resin such as tempered glass can usually be performed using a roller or the like.

  As the surface protective member, a member made of the glass or resin is previously pasted on the surface of the acrylic pressure-sensitive adhesive layer (B) of the pressure-sensitive adhesive sheet, and autoclaved (for example, 40 ° C. to 60 ° C. and 0. 0 ° C.). What was left to stand in an environment of 1 MPa to 1 MPa for about 5 minutes to 60 minutes) can be used.

  The surface protection member can be easily affixed to the surface of the information display unit constituting the display by hand without using a roller or the like. In the case of the surface protective member of the present invention, bubbles are difficult to enter on the surface between the silicone pressure-sensitive adhesive layer (A) and the surface of the information display unit during the pasting, and there are cases where bubbles have entered. However, since it escapes quickly (excellent in air removal), it is possible to prevent deterioration in appearance due to the bubbles.

  The surface protection member is hard to be scratched and has high transparency as compared with a conventional resin surface protection film with a hard coat having a surface hardness of about 2H, and thus has a good appearance when attached to a display body.

  Examples and comparative examples will be specifically described below.

[Preparation of silicone adhesive]
(Silicone-based adhesive A1)
54 parts by mass of addition-curable dimethylpolysiloxane having a weight average molecular weight of 280,000 as a silicone polymer, 46 parts by mass of dimethylpolysiloxane having a weight average molecular weight of 4500 as a silicone-based tackifier resin, 200 parts by mass of toluene, and 33 parts by mass of methyl ethyl ketone 0.666 parts by mass of catalyst “CAT-PL-50T” (manufactured by Shin-Etsu Chemical Co., Ltd., reaction product of chloroplatinic acid and vinyl group-containing siloxane) is added to the mixture of the components, and 15 minutes using a stirrer By stirring, a silicone-based pressure-sensitive adhesive A1 was obtained.

(Silicone-based adhesive A2)
50 mass parts of addition-curable dimethylpolysiloxane having a weight average molecular weight of 280,000 as a silicone polymer, 50 mass parts of dimethylpolysiloxane having a weight average molecular weight of 4500 as a silicone-based tackifier resin, 200 mass parts of toluene, and 33 mass of methyl ethyl ketone 0.833 parts by mass of the catalyst “CAT-PL-50T” (Shin-Etsu Chemical Co., Ltd., reaction product of chloroplatinic acid and vinyl group-containing siloxane) was added to the mixture of the components, and the mixture was stirred for 15 minutes. By stirring, silicone pressure sensitive adhesive A2 was obtained.

(Silicone adhesive A3)
58 parts by mass of addition-curable dimethylpolysiloxane having a weight average molecular weight of 280,000 as a silicone polymer, 42 parts by mass of dimethylpolysiloxane having a weight average molecular weight of 4500 as a silicone-based tackifier resin, 200 parts by mass of toluene, and 33 parts by mass of methyl ethyl ketone 0.833 parts by mass of the catalyst “CAT-PL-50T” (Shin-Etsu Chemical Co., Ltd., reaction product of chloroplatinic acid and vinyl group-containing siloxane) was added to the mixture of the components, and the mixture was stirred for 15 minutes. By stirring, a silicone-based pressure-sensitive adhesive A3 was obtained.

(Silicone adhesive A4)
62 parts by mass of addition-curable dimethylpolysiloxane having a weight average molecular weight of 280,000 as a silicone polymer, 38 parts by mass of dimethylpolysiloxane having a weight average molecular weight of 4500 as a silicone-based tackifier resin, 200 parts by mass of toluene, and 33 parts by mass of methyl ethyl ketone 0.666 parts by mass of catalyst “CAT-PL-50T” (manufactured by Shin-Etsu Chemical Co., Ltd., reaction product of chloroplatinic acid and vinyl group-containing siloxane) is added to the mixture of the components, and 15 minutes using a stirrer By stirring, silicone pressure sensitive adhesive A4 was obtained.

(Silicone adhesive A5)
90 parts by mass of addition-curable dimethylphenylpolysiloxane having a weight average molecular weight of 280,000 as a silicone polymer, 10 parts by mass of dimethylphenylpolysiloxane having a weight average molecular weight of 550 as a silicone-based tackifier resin, 200 parts by mass of toluene, and methyl ethyl ketone To a mixture of 33 parts by mass, 0.666 parts by mass of a catalyst “CAT-PL-50T” (manufactured by Shin-Etsu Chemical Co., Ltd., a reaction product of chloroplatinic acid and a vinyl group-containing siloxane) is added, and a stirrer is used. By stirring for 15 minutes, a silicone-based pressure-sensitive adhesive A5 was obtained.

(Preparation of acrylic adhesive)
<Preparation of acrylic polymer (1)>
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 95.5 parts by mass of n-butyl acrylate, 0.5 parts by mass of 2-hydroxyethyl acrylate, 4.0 parts by mass of acrylic acid Part, 2,2'-azobisisobutylnitrile 0.2 part as a polymerization initiator is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to obtain an acrylic resin having a weight average molecular weight of 800,000. A polymer (1) solution was obtained.

<Preparation of acrylic tackifying resin>
(Acrylic adhesive B1)
In a reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a dropping funnel and a nitrogen gas inlet, 95.0 parts by mass of methyl methacrylate, 5.0 parts by mass of dimethylaminoethyl methacrylate, 2,2′- as a polymerization initiator An acrylic tackifying resin having a weight average molecular weight of 20,000 was obtained by dissolving 1.0 part by mass of azobisisobutylnitrile in 100 parts by mass of ethyl acetate, followed by nitrogen substitution and polymerizing at 80 ° C. for 8 hours.

  By adding 5 parts by mass of the acrylic tackifying resin to 100 parts by mass of the solid content of the acrylic polymer (1) solution, and then adjusting with ethyl acetate so that the solid content becomes 30% by mass An acrylic adhesive was obtained. The acrylic pressure-sensitive adhesive B1 was obtained by mixing 0.3 parts by mass of the acrylic pressure-sensitive adhesive and the crosslinking agent “E-2XM” (manufactured by Soken Chemical Co., Ltd., epoxy-based crosslinking agent).

(Acrylic adhesive B2)
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 75 parts by mass of methoxyethyl acrylate, 24 parts by mass of n-butyl acrylate, 1 part by mass of hydroxyethyl acrylate, 2 as a polymerization initiator , 2′-azobisisobutylnitrile dissolved in 100 parts by mass of ethyl acetate, purged with nitrogen, and polymerized at 80 ° C. for 8 hours to obtain an acrylic polymer (2) having a weight average molecular weight of 700,000. A solution was obtained.

  0.12 parts by mass of an isocyanate cross-linking agent (manufactured by Soken Chemical Co., Ltd., TD-75 solid content 75% by mass) is added to 100 parts by mass of the solid content of the acrylic copolymer (2) solution, and a stirrer is used. The mixture was stirred for 15 minutes to obtain an acrylic pressure-sensitive adhesive B2.

(Acrylic adhesive B3)
In a reaction vessel equipped with a stirrer, reflux condenser, thermometer, dropping funnel and nitrogen gas inlet, 95.5 parts by mass of n-butyl acrylate, 0.5 parts by mass of 2-hydroxyethyl acrylate, 4.0 parts by mass of acrylic acid As a polymerization initiator, 0.2 parts by mass of 2,2′-azobisisobutylnitrile is dissolved in 100 parts by mass of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to obtain an acrylic copolymer having a weight average molecular weight of 1,000,000. A solution of polymer (3) was obtained.

  10 parts by weight of “KE656” (Arakawa Chemical Industries, Ltd., disproportionated rosin ester) and “Pencel D135” (Arakawa Chemical Industries, Ltd.) with respect to 100 parts by mass of the solid content of the acrylic polymer (3) solution. , Polymerized rosin ester) 5 parts by mass and "FTR6100" (manufactured by Mitsui Chemicals, petroleum resin) 30 parts by mass are mixed and adjusted with toluene so that their solid content is 40% by mass. An agent was obtained. The acrylic pressure-sensitive adhesive is mixed with 1.3 parts by mass of “Coronate L-45” (manufactured by Nippon Polyurethane Industry Co., Ltd., isocyanate-based cross-linking agent) and stirred for 15 minutes using a stirrer. B3 was obtained.

Example 1
Using a lip coater on one side of the polyester film (Toyobo Co., Ltd., “A4300 # 38”) as a base material, the silicone pressure-sensitive adhesive A1 after drying has a thickness of the silicone pressure-sensitive adhesive layer. A silicone pressure-sensitive adhesive layer was formed by applying the coating to 30 μm and drying at 140 ° C. for 2 minutes.

  A single-sided adhesive tape was obtained by laminating a polyester film (“E5000 # 50” manufactured by Toyobo Co., Ltd.) as a release liner on the surface of the silicone-based adhesive layer.

  Next, the acrylic pressure-sensitive adhesive B1 was applied onto a release liner “PET38 × 1 A3” manufactured by Nipper Corporation using a lip coater so that the thickness of the acrylic pressure-sensitive adhesive layer after drying was 20 μm. And an acrylic pressure-sensitive adhesive layer was formed by drying at 100 ° C. for 2 minutes.

  Next, the said acrylic adhesive layer was affixed on the other surface of the base material which comprises the said single-sided adhesive tape, and the double-sided adhesive sheet was obtained by curing at 40 degreeC for 48 hours.

(Example 2)
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the silicone-based adhesive A2 was used instead of the silicone-based adhesive A1.

Example 3
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the silicone-based adhesive A3 was used instead of the silicone-based adhesive A1.

Example 4
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the thickness of the silicone-based PSA layer was changed from 30 μm to 50 μm.

(Example 5)
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the thickness of the silicone-based PSA layer was changed from 30 μm to 20 μm.

(Example 6)
A double-sided pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive B2 was used instead of the acrylic pressure-sensitive adhesive B1.

(Example 7)
Example 1 except that a polyester film (manufactured by Yuchinika Co., Ltd., “S-50”, thickness 50 μm) was used instead of a polyester film (manufactured by Toyobo Co., Ltd., “A4300 # 38”). A double-sided PSA sheet was obtained in the same manner.

(Comparative Example 1)
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the silicone-based adhesive A4 was used instead of the silicone-based adhesive A1.

(Comparative Example 2)
A double-sided PSA sheet was obtained in the same manner as in Example 1 except that the silicone-based adhesive A5 was used instead of the silicone-based adhesive A1.

  (Measurement of tensile strength)

  Under the environment of 23 ° C. and 50% RH, the double-sided pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 50 mm width and 100 mm length, and the surface composed of the acrylic pressure-sensitive adhesive layer and an aluminum plate A test piece was prepared by using a double-sided pressure-sensitive adhesive sheet “# 8625UJ” manufactured by DIC Corporation and backing the acrylic pressure-sensitive adhesive layer.

  The test piece was placed so that the silicone-based pressure-sensitive adhesive layer was on top, and cut into a width of 25 mm on the silicone-based pressure-sensitive adhesive layer “S-25” (manufactured by Unitika Ltd., polyester film thickness 25 μm). Were mounted on the upper surface by reciprocating a 2 kg roller once, and then left at 23 ° C. and 50% RH for 1 hour.

  Thereafter, using a tensile tester (Tensilon RTA-100, manufactured by A & D Co., Ltd.) in a 23 ° C. and 50% RH environment, the “S-25” was changed to the silicone-based pressure-sensitive adhesive under the conditions of a tensile speed of 300 mm / min. The layer was pulled in the direction of 180 ° with respect to the surface of the layer, and the adhesive strength when the layer was peeled was measured.

  In addition, the double-sided PSA sheets obtained in Examples and Comparative Examples were cut into a size of 50 mm width and 100 mm length in an environment of 23 ° C. and 50% RH, and a surface comprising the silicone-based pressure-sensitive adhesive layer and an aluminum plate Were bonded using a double-sided pressure-sensitive adhesive sheet “# 8625HPW” manufactured by DIC Corporation, and a test piece was obtained by lining the silicone-based pressure-sensitive adhesive layer.

  The test piece was placed so that the acrylic pressure-sensitive adhesive layer was on the upper surface, and cut into a width of 25 mm on the acrylic pressure-sensitive adhesive layer (S-25) (manufactured by Unitika Ltd., polyester film thickness 25 μm) Were mounted on the upper surface by reciprocating a 2 kg roller once, and then left at 23 ° C. and 50% RH for 1 hour.

  Thereafter, using a tensile tester (Tensilon RTA-100, manufactured by A & D) at 23 ° C. and 50% RH, the “S-25” was converted to the acrylic pressure-sensitive adhesive under the conditions of a tensile speed of 300 mm / min. The layer was pulled in the direction of 180 ° with respect to the surface of the layer, and the adhesive strength when the layer was peeled was measured.

(Air release)
A member (C-1) having a printing layer (thickness: 10 μm and width: 3 mm) on a frame portion of tempered glass having a length of 10 cm, a width of 6 cm, and a thickness of 0.4 mm was prepared.

  An acrylic pressure-sensitive adhesive layer constituting the double-sided pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples is pasted on the surface of the member (C-1) having the printed layer, and its upper surface (on the surface of the silicone-based pressure-sensitive adhesive layer) The provided release liner surface) was reciprocated once with a 2 kg roller to bond them together.

Next, the laminated material is subjected to an autoclave treatment (left at 55 ° C. and 0.5 MPa for 30 minutes), and then the surface on the double-sided pressure-sensitive adhesive sheet side is irradiated with ultraviolet rays having an integrated light amount of 1000 mJ / cm ² . A surface protective member (FIG. 1) was obtained.

  Next, a test piece was obtained by manually bonding the silicone pressure-sensitive adhesive layer of the surface protective member and a flat plate glass having a thickness of 1 mm. The specimen was placed on black polyethylene terephthalate.

From when the protective member and the plate glass are bonded together by hand until when it is possible to visually confirm that all the bubbles (air) caught in the interface between the silicone-based pressure-sensitive adhesive layer and the plate glass have been removed. Time was measured.
A: All bubbles (air) were released within 3 hours.
○: Over 3 hours and all bubbles (air) were released within 24 hours.
X: Some bubbles (air) remained even after 24 hours.

(Edge lift resistance)
The acrylic pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples and a tempered glass having a thickness of 0.4 mm are laminated, and the upper surface thereof (release liner provided on the surface of the silicone-based pressure-sensitive adhesive layer) The surface protection member was obtained by pasting them together by reciprocating a 2 kg roller, and subjecting them to autoclaving (standing for 30 minutes in an environment of 60 ° C. and 0.5 MPa).

  The silicone-based pressure-sensitive adhesive layer constituting the surface protection member was attached to the surface (glass) of the information display section of the Apple 6 (registered trademark) display manufactured by Apple (Apple) (test piece). At that time, the end portions (frame portions) of the surface protection member and the surface of the information display portion were pressed with fingers so that they were left in an environment at 23 ° C. for 24 hours.

The distance 7 at which the end portion of the surface protection member was peeled off from the surface of the information display portion of the display was measured. Specifically, it was confirmed that an end of an arbitrary side of the surface protection member was peeled off from the surface of the information display unit, and the maximum value of the distance peeled in the surface direction from the one side was measured. Based on the peeled distance 7, the following evaluation criteria were used (see FIG. 2).
A: The peeling distance 7 was less than 1 mm.
A: The peel distance 7 was 1 mm or more and less than 3 mm.
X: The peeling distance 7 was 3 mm or more.

(Reworkability: Silicone adhesive layer)
The test piece after evaluating the “air release property” was left in an environment of 23 ° C. and 50% RH for 7 days, and then the plate glass and the surface protection member constituting the test piece were disassembled by hand. . At that time, the adhesive residue on the surface of the plate glass and the presence or absence of cracks in the tempered glass were evaluated.

  (Double-circle): There was no adhesive residue of the level which can be confirmed visually on the surface of plate glass, and the crack of the tempered glass did not generate | occur | produce.

  ○: Some glue residue or cracked tempered glass was observed on the surface of the plate glass.

  X: Clear adhesive residue or cracked tempered glass was observed on the surface of the plate glass.

(Reworkability: Acrylic adhesive layer)
The surface of the acrylic pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples and the tempered glass having a thickness of 0.4 mm are laminated, and the upper surface thereof (the separation provided on the surface of the silicone pressure-sensitive adhesive layer). A test piece was prepared by pasting 2 kg rollers back and forth on the surface of the mold liner).

  The test piece was left in an environment of 23 ° C. and 50% RH for 7 days, and then the tempered glass and the double-sided pressure-sensitive adhesive sheet constituting the test piece were disassembled by hand. The adhesive residue on the surface of the tempered glass and cracking of the tempered glass were evaluated.

  Further, after the test piece prepared by the above method is autoclaved (left in an environment of 60 ° C. and 0.5 MPa for 30 minutes), the tempered glass and the double-sided pressure-sensitive adhesive sheet constituting the test piece are dismantled by hand. did. The adhesive residue on the surface of the tempered glass and cracking of the tempered glass were evaluated.

  A: In any of the above tests, there was no adhesive residue at a level that could be visually confirmed, and no breakage of the tempered glass occurred.

  ○: In the test of disassembling the test piece after being left for 7 days in an environment of 23 ° C. and 50% RH, there was no adhesive residue at a level that could be visually confirmed, and cracking of the tempered glass did not occur, but autoclave treatment In the test of disassembling the later test piece, some adhesive residue or tempered glass cracking was observed.

  X: In the test of disassembling the test piece after being left for 7 days in an environment of 23 ° C. and 50% RH, clear adhesive residue or tempered glass cracking was observed.

DESCRIPTION OF SYMBOLS 1 Tempered glass 2 Acrylic adhesive layer 3 Base material 4 Silicone adhesive layer 5 Surface protection member 6 Information display part 7 Peeling distance

Claims (9)

A pressure-sensitive adhesive sheet having a silicone pressure-sensitive adhesive layer (A) on at least one surface side of a substrate, wherein the silicone-based pressure-sensitive adhesive layer (A) comprises a silicone polymer (a1) and the silicone polymer. A pressure-sensitive adhesive sheet comprising 70% by mass or more of a silicone-based tackifying resin (a2) based on the total amount of (a1). The silicone polymer (a1) has a weight average molecular weight of 150,000 or more, and the silicone tackifier resin (a2) has a weight average molecular weight of 1000 or more and less than 150,000. The pressure-sensitive adhesive sheet according to 1. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the silicone polymer (a1) is a chain polysiloxane. The said pressure sensitive adhesive layer (A) is provided on one surface side of the base material, and the acrylic pressure sensitive adhesive layer (B) is provided on the other surface side of the base material. The adhesive sheet of any one of Claims. Measured by attaching a polyethylene terephthalate film having a thickness of 25 μm to the silicone-based pressure-sensitive adhesive layer (A) and pulling the polyethylene terephthalate film in a 180 ° direction with respect to the surface of the silicone-based pressure-sensitive adhesive layer (A). A polyethylene terephthalate film having a tensile strength in the range of 0.05 N / 25 mm to 0.3 N / 25 mm and having a thickness of 25 μm is attached to the acrylic pressure-sensitive adhesive layer (B), and the polyethylene terephthalate film is attached to the acrylic The pressure-sensitive adhesive sheet according to claim 4, wherein the tensile strength measured by pulling in a 180 ° direction with respect to the surface of the system pressure-sensitive adhesive layer (B) is in the range of 5 N / 25 mm to 28 N / 25 mm. The thickness of the silicone pressure-sensitive adhesive layer (A) is in the range of 15 μm to 50 μm, and the thickness of the acrylic pressure-sensitive adhesive layer (B) is in the range of 10 μm to 50 μm. Adhesive sheet. A pressure-sensitive adhesive sheet used for bonding between an information display part of a display and a member made of glass or resin, wherein the silicone-based pressure-sensitive adhesive layer (A) constituting the pressure-sensitive adhesive sheet is attached to the surface of the information display part The pressure-sensitive adhesive sheet according to any one of claims 4 to 6, wherein the acrylic pressure-sensitive adhesive layer (B) is affixed to the surface of a member made of the glass or resin. . The surface protection member which has the structure by which the member which consists of glass or resin was previously affixed on the surface of the said acrylic adhesive layer (B) which the adhesive sheet of any one of Claims 1-7 has. The electronic device which has the structure affixed on the surface of the information display part of the said display.

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