WO2014034579A1 - Surface protection sheet - Google Patents

Abstract

Provided is a surface protection sheet wherein it is possible to inhibit "floating" or "peeling" from occurring between inner sheets and it is possible to easily peel off only the outer sheet when peeling off the outer sheet for the purpose of exposing the inner sheet. This surface protection sheet, in which n (n represents an integer of 2 or greater) layers of adhesive sheets having a base layer and an adhesive agent layer are laminated in the order of one to n, is characterized in that the adhesive agent layers of the first to (n-1)th adhesive sheets respectively come into contact with the base layers of the second to nth adhesive sheets, and the deflection amounts of the first to (n-1)th adhesive sheets are larger than the deflection amounts of the sides of second to nth adhesive sheets that respectively come into contact with the adhesive agent layer of the first to (n-1)th adhesive sheets.

Description

Surface protection sheet

The present invention relates to a surface protection sheet.

In recent years, display devices such as liquid crystal displays (LCD) and input devices such as touch panels used in combination with such display devices have been widely used in various fields. In these display devices and input devices, various functional films are used. For example, a film for surface protection for the purpose of surface protection, a hard coat film for the purpose of improving scratch resistance, and an antireflection film for the purpose of improving antireflection properties.

Generally, such a functional film is fixed using an adhesive or the like. For example, as a protective film for protecting a liquid crystal display portion of a mobile phone, a laminated film including a transparent resin layer, an adhesive layer, and a peeling portion for peeling off the adhesive layer is known (see Patent Document 1). When the film surface is scratched or the film surface becomes dirty, the outermost layer film can be exposed by peeling off and removing the outermost layer film.

JP 2005-271812 A

In recent years, thin and fragile adherends are increasing in the field of display devices and input devices. For this reason, when the outer sheet is peeled off for the purpose of exposing the inner sheet free from dirt and scratches after being attached to the adherend even if the adherend is thin or fragile, the laminated sheet Further, it is required that only the outer sheet can be easily peeled, and further, the occurrence of “floating” and “peeling” between the inner sheets is required. In the field of display devices and input devices, the appearance is required to be superior to the design and the like, but if “floating” or “peeling” occurs, the appearance is adversely affected.

Therefore, the object of the present invention is to easily peel only the outer sheet when the outer sheet is peeled off for the purpose of exposing the inner sheet, and further, "floating" and "peeling" between the inner sheets. An object of the present invention is to provide a sheet for surface protection that can suppress generation.
Furthermore, in addition to the above, another object of the present invention is to provide a surface protective sheet having excellent appearance.

Therefore, as a result of intensive studies by the present inventors, in the sheet for surface protection obtained by laminating the pressure-sensitive adhesive sheet having the base material layer and the pressure-sensitive adhesive layer, by selecting the pressure-sensitive adhesive sheet adjacent under specific conditions, It has been found that the pressure-sensitive adhesive sheets can be easily peeled, and further, the occurrence of “floating” and “peeling” between the pressure-sensitive adhesive sheets can be suppressed. The present invention has been completed based on these findings.

That is, the present invention is a surface protective sheet comprising a base material layer and a pressure-sensitive adhesive layer, wherein the first to n (n is an integer of 2 or more) pressure-sensitive adhesive sheets are laminated in that order in n layers,
The adhesive layers of the first to (n-1) adhesive sheets are in contact with the base material layers of the second to n adhesive sheets, respectively.
The amount of deflection defined below of the first to (n-1) pressure-sensitive adhesive sheets is the amount of deflection defined below of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet. The sheet for protecting a surface is characterized by being larger than each other.
Deflection amount (mm): A pressure sensitive adhesive sheet having a width of 20 mm and a length of 10 cm is fixed to a support base so that the protruding portion is a sheet having a width of 20 mm and a length of 8 cm, and then at 23 ° C. for 1 minute. It is determined by measuring the distance in the vertical direction from the original position of the free end of the overhanging portion of the adhesive sheet.

The difference between the amount of deflection of the first to (n-1) pressure-sensitive adhesive sheets and the amount of deflection of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet is 1.0 mm, respectively. The above is preferable.

The thickness of the first to (n-1) pressure-sensitive adhesive sheets is preferably smaller than the thickness of each of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet.

Furthermore, the present invention is a surface protection sheet comprising a base material layer and a pressure-sensitive adhesive layer, wherein the first to n (n is an integer of 2 or more) pressure-sensitive adhesive sheets are laminated in that order.
The adhesive layers of the first to (n-1) adhesive sheets are in contact with the base material layers of the second to n adhesive sheets, respectively.
The base material layers of the first to n-th adhesive sheets are the same,
The composition of the pressure-sensitive adhesive layer of the first to n-th pressure-sensitive adhesive sheets is common,
A surface protection sheet, wherein the thickness of the first to (n-1) pressure-sensitive adhesive sheets is smaller than the thickness of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet. provide.

The difference between the thickness of the first to (n-1) pressure-sensitive adhesive sheets and the thickness of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet is more than 0 and 500 μm or less, respectively. It is preferable to be within.

The surface protective sheet has a release liner on the pressure-sensitive adhesive layer of the nth pressure-sensitive adhesive sheet,
The relationship between the thickness of the release liner, the thickness of the (n-1) th adhesive sheet and the thickness of the nth adhesive sheet is as follows:
(Thickness of release liner) <(thickness of (n-1) th adhesive sheet) <(thickness of nth adhesive sheet)
It is preferable that

The surface protective sheet has a release liner on the pressure-sensitive adhesive layer of the nth pressure-sensitive adhesive sheet,
The thickness of the release liner is preferably 10 to 50 μm.

Furthermore, the present invention provides a structure characterized in that the surface protection sheet is provided on the surface of a member.

When the outer sheet is peeled off for the purpose of exposing the inner sheet, the surface protecting sheet of the present invention can easily peel off only the outer sheet, and “float” or “peel” between the inner sheets. Can be suppressed. Furthermore, the surface protective sheet of the present invention is excellent in appearance.

FIG. 1 is a schematic cross-sectional view showing an example of a surface protecting sheet. FIG. 2 is a schematic cross-sectional view showing an example of the surface protecting sheet. FIG. 3 is a schematic cross-sectional view showing an example of the surface protecting sheet. FIG. 4 is a schematic top view showing the pressure-sensitive adhesive sheet fixed to the support base when measuring the amount of deflection of the pressure-sensitive adhesive sheet. FIG. 5 is a schematic cross-sectional view showing the pressure-sensitive adhesive sheet fixed to the support when measuring the deflection amount of the pressure-sensitive adhesive sheet. FIG. 6 is a schematic cross-sectional view showing the amount of deflection of the adhesive sheet.

Hereinafter, the present invention will be specifically described using an example of the present embodiment with reference to FIGS. In addition, this invention is not limited to the aspect shown to a figure.

(I) Surface Protection Sheet FIG. 1 is a cross-sectional view showing a schematic configuration of a surface protection sheet X which is an example according to the present embodiment. Moreover, FIG. 2 is sectional drawing which shows schematic structure of the sheet | seat Y for surface protection which is another example which concerns on this Embodiment, FIG. 3 is surface protection which is another example which concerns on this Embodiment. It is sectional drawing which shows schematic structure of the sheet | seat Z for work. In this specification, “sheet” includes the meanings of “film” and “tape”.
As shown in FIG. 1, the surface protecting sheet X includes first to n (n is an integer of 2 or more) pressure-sensitive adhesive sheets (first pressure-sensitive adhesive sheet, second pressure-sensitive adhesive sheet, third pressure-sensitive adhesive sheet,... A structure in which n layers of (n-1) th adhesive sheet and nth adhesive sheet) are laminated in that order.
The first to n pressure-sensitive adhesive sheets constituting the surface protecting sheet X have a base material layer and a pressure-sensitive adhesive layer, and are provided on the outer surface of the pressure-sensitive adhesive layer in the n-th pressure-sensitive adhesive sheet which is the outermost layer pressure-sensitive adhesive sheet. Is provided with a release liner.

As shown in FIG. 1, in the surface protecting sheet X, the adhesive layers of the first to (n-1) adhesive sheets are in contact with the base layers of the second to n adhesive sheets, respectively.

The n is not particularly limited as long as it is an integer of 2 or more, but is preferably an integer of 2 to 20, more preferably an integer of 2 to 15, from the viewpoint of production cost, workability, and thinning. Preferably, it is an integer of 2 to 10. Since n may be 2 or more, n may be 2.
Specifically, a surface protective sheet Y having a structure in which three layers of first to third pressure-sensitive adhesive sheets are laminated in that order as shown in FIG. 2 may be used, or as shown in FIG. It is good also as the sheet | seat Z for surface protection which has a structure which laminated | stacked two layers of the adhesive sheet of 2 in that order.

In the surface protective sheet X, the pressure-sensitive adhesive sheet corresponding to the innermost layer (nth pressure-sensitive adhesive sheet) provides a pressure-sensitive adhesive surface used when the surface protective sheet is first attached to the adherend. Specifically, after applying the surface protecting sheet X to the adherend, first, the pressure-sensitive adhesive sheet (first pressure-sensitive adhesive sheet) corresponding to the outermost layer protects the adherend. Next, after the purpose of protection by the pressure-sensitive adhesive sheet corresponding to the outermost layer (first pressure-sensitive adhesive sheet) has been achieved, the pressure-sensitive adhesive sheet corresponding to the outermost layer (first pressure-sensitive adhesive sheet) is peeled off, so that the pressure-sensitive adhesive sheet one layer inside from the outermost layer The (second pressure-sensitive adhesive sheet) is exposed and can be protected by the pressure-sensitive adhesive sheet (second pressure-sensitive adhesive sheet) one layer inside from the outermost layer. Thus, the surface protecting sheet X has a structure in which the inner pressure-sensitive adhesive sheet is exposed by peeling off and removing the outer pressure-sensitive adhesive sheet.

In the surface protecting sheet X, the deflection amounts of the first to (n-1) pressure-sensitive adhesive sheets are larger than the deflection amounts of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet, respectively. . Specifically, in the surface protection sheet X, the deflection amount of the first adhesive sheet is larger than the deflection amount of the second adhesive sheet, and the deflection amount of the second adhesive sheet is larger than the deflection amount of the third adhesive sheet. Large (not shown), the deflection amount of the (n-1) th adhesive sheet is larger than the deflection amount of the nth adhesive sheet. With such a configuration, when the outer adhesive sheet is peeled off for the purpose of exposing the inner adhesive sheet, only the outer adhesive sheet can be easily peeled off, and "floating" or "peeling" between the inner adhesive sheets ”Can be suppressed, leading to an improvement in appearance.

The method for measuring the amount of deflection will be described below with reference to FIGS. FIG. 4 is a schematic top view showing the pressure-sensitive adhesive sheet fixed to the support when measuring the amount of deflection of the pressure-sensitive adhesive sheet, and FIG. 5 is a pressure-sensitive adhesive sheet fixed to the support when measuring the amount of deflection of the pressure-sensitive adhesive sheet. FIG. 6 is a schematic cross-sectional view showing the amount of deflection of the pressure-sensitive adhesive sheet. As shown in FIGS. 4 and 5, in the measurement of the amount of deflection, a pressure-sensitive adhesive sheet 42 having a width of 20 mm and a length of 10 cm, which is a measurement target, is formed on a support base 41 and a protruding portion is a sheet shape having a width of 20 mm and a length of 8 cm. Fix to be. After leaving at 23 ° C. for 1 minute, as shown in FIG. 6, the amount of deflection is obtained by measuring the vertical distance f from the original position of the free end portion of the overhanging portion 421 in the adhesive sheet 42. .

The amount of deflection of the pressure-sensitive adhesive sheet can be adjusted by, for example, the thickness of the pressure-sensitive adhesive sheet, the thickness of the base material layer, the production method of the pressure-sensitive adhesive sheet, and the material constituting the base material layer. Specifically, in the surface protecting sheet X, when the compositions of the pressure-sensitive adhesive layers of the first to nth pressure-sensitive adhesive sheets are the same and the materials of the base material layers of the first to nth pressure-sensitive adhesive sheets are the same, The amount of deflection of the adhesive sheet can be controlled by the thickness of the adhesive sheet.
For this reason, the present invention is “a surface protection sheet comprising a base material layer and a pressure-sensitive adhesive layer, wherein n first to n (n is an integer of 2 or more) pressure-sensitive adhesive sheets are laminated in that order. The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets 1 to (n-1) are in contact with the base material layers of the second to n-th pressure-sensitive adhesive sheets, respectively. The pressure-sensitive adhesive layers of the first to n-th adhesive sheets have the same composition, and the thicknesses of the first to (n-1) pressure-sensitive adhesive sheets are adjacent to the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet. In other words, the surface protecting sheet is smaller than the thickness of the adhesive sheet of n.

In addition, in the said surface protection sheet, that the raw material of a base material layer is common includes the case where the main component of a raw material is common in addition to the case where the raw material of a base material layer is completely the same. For example, when the material of the base material layer is a polymer, it can be determined that the material of the base material layer is common when the main monomer components constituting the polymer are common. More specifically, when the material of the base material layer is a polymer, among the monomer components constituting the polymer, 50% by weight or more (preferably 60% by weight or more, more than the total monomer components (100% by weight) (Preferably 70% by weight or more, more preferably 80% by weight or more, particularly preferably 90% by weight or more) If all the components occupy in common, it can be determined that the material of the base material layer is common. Moreover, in the said surface protection sheet, that the composition of an adhesive layer is common includes the case where a main component is common in addition to the case where the composition of an adhesive layer is completely the same. More specifically, among the components (eg, base polymer, additive, etc.) contained in the pressure-sensitive adhesive layer, 50% by weight or more (preferably 60% by weight or more, preferably) with respect to the total amount of the pressure-sensitive adhesive layer (100% by weight). More preferably 70% by weight or more, still more preferably 80% by weight or more, and particularly preferably 90% by weight or more.

In the surface protecting sheet X, the difference between the deflection amount of the first to (n-1) adhesive sheets and the deflection amount of the second to n adhesive sheets adjacent to and in contact with the adhesive layer side of the adhesive sheet is From the point that the pressure-sensitive adhesive sheet can be more easily peeled off, and from the point of further suppressing the occurrence of "floating" and "peeling" between the pressure-sensitive adhesive sheets at the time of peeling of the pressure-sensitive adhesive sheet, each is preferably 1.0 mm or more, More preferably, it is 3.0 mm or more, More preferably, it is 5.0 mm or more. The upper limit of the difference in the deflection amount is not particularly limited, but is preferably 78 mm or less, more preferably 76 mm or less, and further preferably 72 mm or less.

In the surface protecting sheet X, the adhesive sheet is more easily peeled off, and the occurrence of “floating” and “peeling” between the adhesive sheets during peeling of the adhesive sheet is further suppressed. The thickness of the pressure-sensitive adhesive sheet of 1) is preferably smaller than the thickness of each of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet.

In particular, in the surface protecting sheet X, the difference between the thickness of the first to (n-1) pressure-sensitive adhesive sheets and the thickness of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet is , Preferably in the range of more than 0 and 500 μm or less, more preferably in the range of 5 μm or more and 150 μm or less, and still more preferably in the range of 15 μm or more and 130 μm or less.

In the surface protecting sheet X, the thickness of the first to nth adhesive sheets is not particularly limited, but is preferably in the range of 1 to 1000 μm, more preferably in the range of 5 to 500 μm, More preferably, it is in the range of 10 to 200 μm.

The total thickness of the surface protecting sheet X is not particularly limited, but may be 2 to 2000 μm, preferably 5 to 1000 μm, more preferably 20 to 500 μm, still more preferably 40 to 260 μm, and particularly preferably 60 to 230 μm. The total thickness does not include the thickness of the release liner.

In the present embodiment, the first to n-th adhesive sheets have been described by exemplifying the surface protection sheet X having a configuration including a base material layer and an adhesive layer. However, the present invention is not limited to this. The configuration is not limited. You may have other layers (layers other than the said base material layer and the said adhesive layer) between the base material layer and the adhesive layer as needed.
Moreover, although this Embodiment illustrated and demonstrated the form in which the adhesive layer surface of the nth adhesive sheet was protected by the release liner, this invention is not limited to such a structure. For example, the back surface (the surface opposite to the pressure-sensitive adhesive layer) of the base material layer of the first pressure-sensitive adhesive sheet is subjected to a peeling treatment, and wound so that the peel-treated surface is in contact with the pressure-sensitive adhesive layer of the nth pressure-sensitive adhesive sheet. It may be in a rotated form.

(Base material layer)
The substrate constituting the substrate layer of the first to nth pressure-sensitive adhesive sheets is not particularly limited, but a plastic substrate (polymer substrate) is preferable. The base material may be a single-layer base material, or may have a laminated structure of two or more layers.

The material constituting the plastic substrate is not particularly limited. For example, polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate; polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymer Polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, celluloses, fluororesin, polyether, polyether amide, polyether ether ketone, polyphenylene sulfide Polystyrene resins such as polystyrene; polycarbonate; polyethersulfone; and the like. In addition, the said material can be used individually or in combination of 2 or more types.

Among them, the material constituting the plastic substrate is preferably polyester, more preferably polyethylene terephthalate (PET), because of the good balance of strength, handleability (handling properties), cost, dimensional stability, and anchoring force. .

The deformability of the base material may be controlled by a stretching process (uniaxial stretching or biaxial stretching) or the like. In addition, the surface of the base material is subjected to a conventional surface treatment, for example, chromic acid treatment, ozone exposure, flame exposure, high-voltage impact exposure, ionizing radiation treatment, in order to enhance the adhesion with the pressure-sensitive adhesive layer as necessary. An oxidation treatment or the like by a chemical or physical method such as the above may be performed.

Moreover, the base material may be subjected to primer treatment on the surface thereof. As said primer process, the primer process for improving the adhesiveness with an adhesive layer is mentioned preferably.

Furthermore, the base material may be provided with a hard coat treatment from the viewpoint of improving the scratch resistance (abrasion resistance) of the surface. When such a hard coat layer is provided, the protective function of the surface protective sheet can be further improved. The hard coat layer may be a layer having high antireflection properties.

The pencil hardness of the surface of the hard coat layer (hard coat layer surface) is not particularly limited, but is preferably HB or higher, more preferably H or higher. The pencil hardness can be measured according to the scratch hardness test (pencil method) described in JIS K5600-5-4.

The hard coat layer is not particularly limited, and examples thereof include known or conventional hard coat layers. Examples of resin components that form the hard coat layer include photopolymerization of thermosetting resins such as siloxane resins, and monomers and oligomers such as ester, acrylic, urethane, amide, silicone, and epoxy resins Ionizing radiation curable resins (for example, UV curable resins) that are cured with an agent, ionomer radiation curable resins (for example, UV curable resins) such as acrylic / urethane and acrylic / epoxy compounds Resin). Among these, from the viewpoint of improving scratch resistance, ionizing radiation curable resins are preferable, and ultraviolet curable resins are more preferable. That is, the hard coat layer is preferably a cured film cured by irradiating an ionizing radiation (particularly, ultraviolet rays) to an ionizing radiation curable resin (particularly, an ultraviolet curable resin). The hard coat layer may have a single layer configuration or a multi-layer configuration. Furthermore, the thickness of the hard coat layer is not particularly limited, and may be, for example, a known or conventional thickness.

The base material may be, for example, a base material that has been subjected to primer treatment on one surface to improve adhesion to the pressure-sensitive adhesive layer and provided with a hard coat layer on the other surface.

The thickness of the substrate is not particularly limited, but is preferably 1 to 500 μm, more preferably 5 to 300 μm, and still more preferably 10 to 200 μm. The thickness of the base material includes the thickness of the hard coat layer when the hard code layer is provided.

(Adhesive layer)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet is not particularly limited. For example, an acrylic pressure-sensitive adhesive layer, a rubber-based pressure-sensitive adhesive layer, a vinyl alkyl ether-based pressure-sensitive adhesive layer, a silicone-based pressure-sensitive adhesive layer, a polyester-based pressure-sensitive adhesive layer, and a polyamide-based pressure-sensitive adhesive layer. Examples thereof include an adhesive layer, a urethane-based adhesive layer, a fluorine-based adhesive layer, and an epoxy-based adhesive layer.

The pressure-sensitive adhesive layer is formed of a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition may have any form, and may be, for example, an active energy ray curable type, a solvent type (solution type), an emulsion type, or a hot melt type (hot melt type). .

Especially, as the above-mentioned pressure-sensitive adhesive layer, an acrylic pressure-sensitive adhesive layer and a silicone-based pressure-sensitive adhesive layer are preferable in terms of easy adjustment of the adhesive force.

The acrylic pressure-sensitive adhesive layer or the silicone pressure-sensitive adhesive layer contains 50% by weight or more of the acrylic polymer or silicone-based polymer as a base polymer with respect to the total amount (100% by weight) of the pressure-sensitive adhesive layer. Preferably, it contains 60% by weight or more.

The silicone pressure-sensitive adhesive layer is formed of a silicone pressure-sensitive adhesive composition. Although it does not specifically limit as said silicone type adhesive layer, For example, a peroxide bridge | crosslinking type silicone type adhesive composition (peroxide hardening type silicone type adhesive composition) and an addition reaction type silicone type adhesive composition Preferably, the silicone-based pressure-sensitive adhesive layer formed by (1) is mentioned, and more preferably, the silicone-based pressure-sensitive adhesive layer formed by the addition reaction type silicone-based pressure-sensitive adhesive composition.

Further, as the silicone pressure-sensitive adhesive composition, a phenyl group-containing silicone pressure-sensitive adhesive composition is preferable. Examples of the phenyl group-containing silicone pressure-sensitive adhesive composition include polyalkylphenyl silicone pressure-sensitive adhesive compositions such as a polymethylphenyl silicone-based pressure-sensitive adhesive composition and a polyethylphenyl silicone-based pressure-sensitive adhesive composition.

The addition reaction type silicone pressure-sensitive adhesive composition is preferably an addition reaction type silicone pressure sensitive adhesive composition (an addition reaction type phenyl group-containing silicone pressure sensitive adhesive composition) based on an organopolysiloxane having a phenyl group. . Examples of the organopolysiloxane having a phenyl group in such an addition reaction type phenyl group-containing silicone pressure-sensitive adhesive composition include polymethylphenylsiloxane (polymethylphenylsilicone) and polyethylphenylsiloxane (polyethylene). And polyalkylphenyl siloxane (polyalkylphenyl silicone) such as ethylphenyl silicone.

The addition reaction type silicone pressure-sensitive adhesive composition preferably contains a silicone rubber and a silicone resin.

The silicone rubber is not particularly limited as long as it is a silicone-based rubber component, but a silicone rubber comprising an organopolysiloxane having a phenyl group (particularly, an organopolysiloxane having methylphenylsiloxane as a main constituent unit). Is preferred. Various functional groups such as vinyl groups may be introduced into the organopolysiloxane in such a silicone rubber, if necessary. The weight average molecular weight of the organopolysiloxane is not particularly limited, but is preferably 150,000 or more, more preferably 280,000 to 1,000,000, and further preferably 500,000 to 900,000.

The silicone resin is not particularly limited as long as it is a silicone-based resin used in a silicone-based pressure-sensitive adhesive (silicone-based pressure-sensitive adhesive). For example, the structural unit “R ₃ —Si _1/2 ” is used. M unit consisting, Q units comprising constituent units "SiO _2", at least is selected from the D units comprising T units consisting of the structural units "R-SiO _3/2", and the structural unit "R ₂ -SiO" 1 Examples thereof include a silicone resin containing an organopolysiloxane composed of a (co) polymer having a seed unit. In addition, R in the said structural unit shows a hydrocarbon group or a hydroxyl group. Examples of the hydrocarbon group include an aliphatic hydrocarbon group (an alkyl group such as a methyl group and an ethyl group), an alicyclic hydrocarbon group (a cycloalkyl group such as a cyclohexyl group), an aromatic hydrocarbon group ( Aryl group such as phenyl group and naphthyl group). The ratio (ratio) between the “M unit” and “at least one unit selected from Q unit, T unit and D unit” is, for example, the former / the latter (molar ratio) = 0.3 / 1. It is preferable that the ratio is ˜1.5 / 1 (preferably 0.5 / 1 to 1.3 / 1).

Various functional groups such as vinyl groups may be introduced into the organopolysiloxane in the silicone resin as necessary. The functional group to be introduced may be a functional group capable of causing a crosslinking reaction. The weight average molecular weight of the organopolysiloxane in the silicone resin is preferably 1000 or more, more preferably 1000 to 20000, and still more preferably 1500 to 10,000.

The blending ratio of the silicone rubber and the silicone resin is not particularly limited, but the silicone resin is preferably 100 to 220 parts by weight (particularly 120 to 180 parts by weight) with respect to 100 parts by weight of the silicone rubber.

In the silicone-based pressure-sensitive adhesive composition containing silicone rubber and silicone resin, the silicone rubber and the silicone resin may be in a mixed state where the silicone rubber and the silicone resin are mixed. May be in a condensed state as a condensate (particularly a partial condensate) by reaction.

The silicone-based pressure-sensitive adhesive composition may contain additives such as a crosslinking agent, a filler, a plasticizer, an anti-aging agent, an antistatic agent, and a colorant (pigment, dye, etc.) as necessary. Good. Moreover, you may contain a catalyst (especially platinum-type catalyst etc.). In addition, an additive can be used individually or in combination of 2 or more types.

In particular, the silicone pressure-sensitive adhesive composition containing the silicone rubber and the silicone resin preferably contains a crosslinking agent from the viewpoint of obtaining a silicone pressure-sensitive adhesive layer that is a crosslinked structure. Such a crosslinking agent is not particularly limited, and preferred examples include a siloxane-based crosslinking agent (silicone-based crosslinking agent) and a peroxide-based crosslinking agent. In addition, a crosslinking agent can be used individually or in combination of 2 or more types.

The siloxane-based crosslinking agent is not particularly limited, but polyorganohydrogensiloxane having two or more hydrogen atoms bonded to silicon atoms in the molecule is preferably exemplified. In such polyorganohydrogensiloxane, various organic groups other than hydrogen atoms may be bonded to the silicon atoms to which hydrogen atoms are bonded. Examples of the organic group include alkyl groups such as a methyl group and an ethyl group; aryl groups such as a phenyl group; and halogenated alkyl groups. Among these, from the viewpoints of synthesis and handling, an alkyl group is preferable, and a methyl group is more preferable. The skeleton structure of polyorganohydrogensiloxane may have any of a linear, branched, or cyclic skeleton structure, but a linear structure is preferable.

Examples of commercially available silicone pressure-sensitive adhesive compositions include trade name “X-40-3306” (manufactured by Shin-Etsu Chemical Co., Ltd., an addition reaction type silicone pressure-sensitive adhesive composition).

On the other hand, the acrylic pressure-sensitive adhesive layer preferable as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet in the surface protecting sheet of the present invention contains an acrylic polymer as a base polymer. The acrylic pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive composition.

The acrylic polymer is not particularly limited, but is preferably a polymer composed of (meth) acrylic acid alkyl ester having a linear or branched alkyl group as a main monomer component. The “(meth) acryl” represents “acryl” and / or “methacryl” (any one or both of “acryl” and “methacryl”), and the same applies to others.

Examples of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group (hereinafter sometimes simply referred to as “(meth) acrylic acid alkyl ester”) include, for example, methyl (meth) acrylate, Ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, (meth) acrylic T-butyl acid, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( (Meth) acrylate isooctyl, (meth) acrylate nonyl, (meth) acrylate isononyl, (Meth) acrylic acid decyl, (meth) acrylic acid isodecyl, (meth) acrylic acid undecyl, (meth) acrylic acid dodecyl, (meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, (meth) acrylic acid pentadecyl, (meta Alkyl (meth) acrylates having an alkyl group of 1 to 20 carbon atoms such as hexadecyl acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate Examples include esters. In addition, the said (meth) acrylic-acid alkylester can be used individually or in combination of 2 or more types.

Among them, the (meth) acrylic acid alkyl ester is preferably a (meth) acrylic acid alkyl ester having an alkyl group having 2 to 10 carbon atoms, more preferably n-butyl (meth) acrylate (n-BA), acrylic. The acid 2-ethylhexyl (2EHA).

Although content of the said (meth) acrylic-acid alkylester is not specifically limited, 40 weight% or more with respect to the monomer component whole quantity (total weight, 100 weight%) which comprises an acrylic polymer from an adhesive point ( For example, it is preferably 40 to 100% by weight), more preferably 50 to 99% by weight.

The acrylic polymer may contain a copolymerizable monomer as a constituent monomer component from the viewpoint of enabling tuning of characteristics, proper use according to the purpose, and imparting a function as required. Moreover, a copolymerizable monomer can be used individually or in combination of 2 or more types.

Examples of the copolymerizable monomer include polar group-containing monomers. Examples of the polar group-containing monomer include (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, and acid anhydrides thereof (for example, acid anhydrides such as maleic anhydride and itaconic anhydride). Carboxyl group-containing monomers such as group-containing monomers); 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate Hydroxyl group-containing monomers such as vinyl alcohol and allyl alcohol; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N- Butoxymethyl (meth) acrylamide Amide group-containing monomers such as N-hydroxyethyl (meth) acrylamide; Amino group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; Epoxy group-containing monomers such as glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinyl-2-pyrrolidone, (meth) acryloylmorpholine, N-vinyl piperidone, Heterocycle-containing vinyl monomers such as N-vinyl piperazine, N-vinyl pyrrole, N-vinyl imidazole, vinyl pyridine, vinyl pyrimidine and vinyl oxazole; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; Phosphoric acid group-containing monomers such as mud carboxyethyl acryloyl phosphate; cyclohexyl maleimide, imide group-containing monomers such as isopropyl maleimide; an isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate. In addition, the said polar group containing monomer can be used individually or in combination of 2 or more types.

Among them, the polar group-containing monomer is preferably a carboxyl group-containing monomer or a hydroxyl group-containing monomer, more preferably acrylic acid, 4-hydroxybutyl acrylate, or 2-hydroxyethyl acrylate.

The content of the polar group-containing monomer is not particularly limited, but is preferably 1 to 20% by weight, more preferably 1 to 15% by weight with respect to the total amount of monomer components (100% by weight) constituting the acrylic polymer. It is.

Also, examples of the copolymerizable monomer include polyfunctional monomers. The said polyfunctional monomer means the monomer which has 2 or more ethylenically unsaturated groups in 1 molecule. Although it does not specifically limit as said ethylenically unsaturated group, For example, radical polymerizable functional groups, such as a vinyl group, a propenyl group, an isopropenyl group, a vinyl ether group (vinyloxy group), an allyl ether group (allyloxy group), are mentioned. .

Examples of the polyfunctional monomer include hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, and neopentyl. Glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, Examples include allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, and urethane acrylate. In addition, the said polyfunctional monomer can be used individually or in combination of 2 or more types.

Furthermore, examples of the copolymerizable monomer include (meth) acrylic acid alkoxyalkyl ester [alkoxyalkyl (meth) acrylate]. The (meth) acrylic acid alkoxyalkyl ester is not particularly limited. For example, (meth) acrylic acid 2-methoxyethyl, (meth) acrylic acid 2-ethoxyethyl, (meth) acrylic acid methoxytriethylene glycol, Examples include 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 4-methoxybutyl (meth) acrylate, 4-ethoxybutyl (meth) acrylate, and the like. In addition, the said (meth) acrylic-acid alkoxyalkylester can be used individually or in combination of 2 or more types.

Furthermore, as the copolymerizable monomer, in addition to the polar group-containing monomer, the polyfunctional monomer, and the (meth) acrylic acid alkoxyalkyl ester, for example, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate And (meth) acrylic acid esters having an alicyclic hydrocarbon group such as isobornyl (meth) acrylate, and aromatic hydrocarbon groups such as phenyl (meth) acrylate, phenoxyethyl (meth) acrylate, and benzyl (meth) acrylate (Meth) acrylic acid esters other than the above (meth) acrylic acid alkyl esters, the above (meth) acrylic acid alkoxyalkyl esters, the above polar group-containing monomers and the above polyfunctional monomers; vinyl acetate , Propion Vinyl esters such as vinyl; styrene, aromatic vinyl compounds such as vinyl toluene; vinyl ethers such as vinyl alkyl ethers; ethylene, butadiene, isoprene, olefins or dienes such as isobutylene and vinyl chloride.

The acrylic polymer can be obtained by polymerizing the monomer component by a known and usual polymerization method. Examples of the polymerization method include solution polymerization method, emulsion polymerization method, bulk polymerization method, polymerization method by active energy ray irradiation (active energy ray polymerization method), and the like. Among these, the solution polymerization method and the active energy ray polymerization method are preferable in terms of transparency, water resistance, cost, and the like.

In forming the acrylic polymer, a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator) can be used depending on the type of polymerization reaction. In addition, a polymerization initiator can be used individually or in combination of 2 or more types.

The thermal polymerization initiator is used particularly when the acrylic polymer is obtained by solution polymerization. Examples of the thermal polymerization initiator include azo initiators, peroxide polymerization initiators (eg, dibenzoyl peroxide, tert-butyl permaleate), redox polymerization initiators, and the like. Of these, the azo initiators disclosed in JP-A No. 2002-69411 are particularly preferable. Such an azo-based initiator is preferable because a decomposition product of the initiator hardly remains in the acrylic polymer as a part that causes generation of a heat generation gas (outgas). Examples of the azo initiator include 2,2′-azobisisobutyronitrile (hereinafter sometimes referred to as AIBN), 2,2′-azobis-2-methylbutyronitrile (hereinafter referred to as AMBN). And 2,2′-azobis (2-methylpropionic acid) dimethyl, 4,4′-azobis-4-cyanovaleric acid, and the like. The amount of the azo initiator used is preferably 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.3 parts by weight with respect to the total amount (100 parts by weight) of monomer components constituting the acrylic polymer. Parts by weight.

The photopolymerization initiator is used particularly when the acrylic polymer is obtained by active energy ray polymerization. The photopolymerization initiator is not particularly limited. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photo Examples thereof include an active oxime photopolymerization initiator, a benzoin photopolymerization initiator, a benzyl photopolymerization initiator, a benzophenone photopolymerization initiator, a ketal photopolymerization initiator, and a thioxanthone photopolymerization initiator.

Examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane-1-one, Anisole methyl ether etc. are mentioned. Examples of the acetophenone photopolymerization initiator include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4-phenoxydichloroacetophenone, 4- (t-butyl). ) Dichloroacetophenone and the like. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone and 1- [4- (2-hydroxyethyl) phenyl] -2-methylpropan-1-one. It is done. Examples of the aromatic sulfonyl chloride photopolymerization initiator include 2-naphthalenesulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime. Examples of the benzoin photopolymerization initiator include benzoin. Examples of the benzyl photopolymerization initiator include benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and the like.

The amount of the photopolymerization initiator used is not particularly limited, but is preferably 0.01 to 0.2 parts by weight, more preferably 0 with respect to the total amount of monomer components (100 parts by weight) constituting the acrylic polymer. .05 to 0.15 parts by weight.

The acrylic pressure-sensitive adhesive layer is formed of the acrylic pressure-sensitive adhesive composition, but the acrylic pressure-sensitive adhesive composition may contain a crosslinking agent. By using the said crosslinking agent, the acrylic polymer in the said acrylic adhesive layer can be bridge | crosslinked and the cohesion force of an acrylic adhesive layer can be improved. In addition, a crosslinking agent can be used individually or in combination of 2 or more types.

Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, and metal salt crosslinking agents. Examples thereof include a crosslinking agent, a carbodiimide crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, and an amine crosslinking agent. Of these, isocyanate crosslinking agents and epoxy crosslinking agents are preferred.

Examples of the isocyanate crosslinking agent (polyfunctional isocyanate compound) include lower aliphatic polyisocyanates such as 1,2-ethylene diisocyanate, 1,4-butylene diisocyanate, 1,6-hexamethylene diisocyanate; cyclopentylene diisocyanate Alicyclic polyisocyanates such as cyclohexylene diisocyanate, isophorone diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate; 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate And aromatic polyisocyanates such as xylylene diisocyanate. Examples of the isocyanate-based crosslinking agent include trimethylolpropane / tolylene diisocyanate adduct [manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate L”], trimethylolpropane / hexamethylene diisocyanate adduct [Japan Polyurethane Industry Co., Ltd. , Product name “Coronate HL”], product name “Coronate HX” (Nippon Polyurethane Industry Co., Ltd.), trimethylolpropane / xylylene diisocyanate adduct [Mitsui Chemicals, product name “Takenate 110N”] Goods are also mentioned.

Examples of the epoxy crosslinking agent (polyfunctional epoxy compound) include N, N, N ′, N′-tetraglycidyl-m-xylenediamine, diglycidylaniline, and 1,3-bis (N, N-diglycidyl). Aminomethyl) cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, sorbitol polyglycidyl ether Glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, tri Tyrolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris (2-hydroxyethyl) isocyanurate, resorcin diglycidyl ether, bisphenol-S-diglycidyl ether, intramolecular And an epoxy resin having two or more epoxy groups. As said epoxy type crosslinking agent, commercial items, such as brand name "Tetrad C" (made by Mitsubishi Gas Chemical Co., Ltd.), are further mentioned.

The content of the crosslinking agent in the acrylic pressure-sensitive adhesive composition is not particularly limited, but is preferably 0.001 to 15 parts by weight with respect to the total amount of monomer components (100 parts by weight) constituting the acrylic polymer, More preferably, it is 0.01 to 12 parts by weight.

In the acrylic pressure-sensitive adhesive composition, in addition to the crosslinking agent, if necessary, a crosslinking accelerator, a silane coupling agent, a tackifying resin (rosin derivative, polyterpene resin, petroleum resin, oil-soluble phenol, etc.), Known additives such as anti-aging agents, fillers, colorants (pigments and dyes), UV absorbers, antioxidants, chain transfer agents, plasticizers, softeners, surfactants, antistatic agents, stabilizers, etc. However, you may contain in the range which does not impair the characteristic of this invention.

The pressure-sensitive adhesive sheet in the surface protecting sheet of the present invention can be obtained by a known or conventional method for forming a pressure-sensitive adhesive layer. For example, the pressure-sensitive adhesive sheet having the silicone-based pressure-sensitive adhesive layer can be obtained by applying (coating) the silicone-based pressure-sensitive adhesive composition onto the base material layer, followed by drying by heating and curing. Moreover, although the adhesive sheet which has the said acrylic adhesive layer is not specifically limited, For example, it can obtain by methods, such as the following (1) or (2).
(1) An acrylic pressure-sensitive adhesive composition containing an acrylic monomer mixture or a partial polymer thereof and, if necessary, an additive such as a photopolymerization initiator or a crosslinking agent is applied (coated) on the base material layer. Irradiating with active energy rays and curing to form an acrylic pressure-sensitive adhesive layer (2) Acrylic pressure-sensitive adhesive composition (solution) containing an acrylic polymer, a solvent, and optionally additives such as a crosslinking agent ) Is applied (coated) on the base material layer, and dried and / or cured to form an acrylic pressure-sensitive adhesive layer. When preparing the pressure-sensitive adhesive layer, a drying step is further provided as necessary. May be. Moreover, an adhesive sheet may be produced by transferring the adhesive layer produced previously to a base material layer.

In addition, a well-known coating method can be utilized for application | coating (coating) of the said adhesive composition. For example, it can apply | coat using a conventional coater (A gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, a direct coater etc.).

The thickness of the pressure-sensitive adhesive layer (for example, the silicone pressure-sensitive adhesive layer or the acrylic pressure-sensitive adhesive layer) is not particularly limited, but is preferably 5 to 100 μm, more preferably 5 to 90 μm, and still more preferably 10 to 75 μm. It is.

(Release liner)
The release liner that can be used on the pressure-sensitive adhesive layer of the nth pressure-sensitive adhesive sheet in the surface protecting sheet of the present invention is not particularly limited, and a known or conventional release liner can be used.

For example, as the release liner used in the silicone-based pressure-sensitive adhesive layer, polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT); polyethylene (PE), polypropylene (PP) Olefin resins containing α-olefin as a monomer component such as polymethylpentene (PMP), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA); polyvinyl chloride (PVC); vinyl acetate resin Polycarbonate (PC); polyphenylene sulfide (PPS); amide resins such as polyamide (nylon), wholly aromatic polyamide (aramid); polyimide resins; polyether ether ketone (PEEK); polyethylene (PE), poly Olefin resins such as pyrene (PP); polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-vinylidene fluoride copolymer A plastic film composed of a fluorine-based resin or the like is preferred.

The release liner used for the acrylic pressure-sensitive adhesive layer includes, for example, a release liner having a release layer (release treatment layer) on at least one surface of a release liner base material, and a low adhesion release liner made of a fluoropolymer. And a low-adhesive release liner made of a nonpolar polymer. Moreover, the release liner base material (namely, release liner base material itself) which does not have a release layer is also mentioned. The fluorine-based polymer is not particularly limited. For example, polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, chlorofluoroethylene-fluoride And vinylidene copolymer. The nonpolar polymer is not particularly limited, and examples thereof include olefin resins such as polyethylene (PE) and polypropylene (PP). Among these, it is preferable to use a release liner having a release layer on at least one surface of the release liner substrate, or a release liner substrate having no release layer (that is, the release liner substrate itself).

The release liner substrate is not particularly limited, and examples thereof include a plastic film. Examples of such plastic films include polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT); polyethylene (PE), polypropylene (PP), and polymethylpentene (PMP). ), Olefin resins containing α-olefin as a monomer component such as ethylene-propylene copolymer, ethylene-vinyl acetate copolymer (EVA); polyvinyl chloride (PVC); vinyl acetate resin; polycarbonate (PC); Examples include polyphenylene sulfide (PPS); amide resins such as polyamide (nylon) and wholly aromatic polyamide (aramid); polyimide resins; and polyether ether ketone (PEEK).Among these, from the viewpoints of processability, availability, workability, dust resistance, cost, and the like, a plastic film formed from a polyester resin is preferable, and a PET film is more preferable.

The release treatment agent constituting the release layer is not particularly limited, and examples include release treatment agents such as silicone release treatment agents, fluorine release treatment agents, long-chain alkyl release treatment agents, and molybdenum sulfide. Among these, a silicone-based release treatment agent is preferable from the viewpoint of release control and stability over time. In addition, an exfoliation processing agent can be used individually or in combination of 2 or more types.

The release liner can be produced by a known and usual method.

The thickness of the release liner is not particularly limited, but when the release liner is peeled off to expose the adhesive surface in order to attach the surface protection sheet to the adherend, “floating” or “peel” between the adhesive sheets. It is preferable to satisfy the following relationship from the viewpoint of suppressing the occurrence of.
(Thickness of release liner) <(thickness of (n-1) th adhesive sheet) <(thickness of nth adhesive sheet)

The thickness of the release liner is not particularly limited, but it is 10 to 50 μm from the viewpoint of suppressing the occurrence of “floating” or “peeling” between the adhesive sheets when the release liner is peeled to expose the adhesive surface. More preferably, it is 12 to 45 μm, more preferably 25 to 38 μm.

In particular, the release liner satisfies the following relationship:
(Thickness of release liner) <(thickness of (n-1) th adhesive sheet) <(thickness of nth adhesive sheet)
The thickness is particularly preferably 10 to 50 μm.

(Surface protection sheet)
The (n-1) pressure-sensitive adhesive sheet of the surface protective sheet of the present invention has an adhesive strength to a polyethylene terephthalate film (PET form) from the viewpoint of obtaining sufficient adhesion and easy peelability to the n-th pressure-sensitive adhesive sheet. Is preferably 0.1 to 9.0 gf / 25 mm, more preferably 0.2 to 5.0 gf / 25 mm.

In the present specification, the adhesive strength (180 ° peel adhesive strength) (gf / 25 mm) is, for example, using a tensile tester, in an atmosphere of 23 ° C. and 50% RH, a tensile speed of 300 mm / min, and a peel angle. It can obtain | require by peeling off an adhesive sheet from a to-be-adhered body on 180 degree conditions.

In the nth pressure-sensitive adhesive sheet of the surface protective sheet of the present invention, when the (n-1) th pressure-sensitive adhesive sheet is peeled off from the n-th pressure-sensitive adhesive sheet, “floating” or “peeling” occurs between the pressure-sensitive adhesive sheets. From the viewpoint of suppressing and obtaining sufficient adhesion to the adherend, the adhesive strength to glass (glass plate) is preferably 0.5 to 30 gf / 25 mm, more preferably 1.5 to 15 gf. / 25 mm.

In the nth pressure-sensitive adhesive sheet of the surface protective sheet of the present invention, when the (n-1) th pressure-sensitive adhesive sheet is peeled off from the n-th pressure-sensitive adhesive sheet, “floating” or “peeling” occurs between the pressure-sensitive adhesive sheets. From the viewpoint of suppressing and obtaining sufficient adhesion to the adherend, the adhesive strength to aluminum (aluminum plate) is preferably 0.5 to 30 gf / 25 mm, more preferably 1.5 to 15 gf. / 25 mm.

In particular, the surface protective sheet of the present invention is more easily peelable while obtaining sufficient adhesion between the (n-1) th adhesive sheet and the nth adhesive sheet. When the n-1 pressure-sensitive adhesive sheet is peeled from the n-th pressure-sensitive adhesive sheet, the occurrence of “floating” or “peeling” between the pressure-sensitive adhesive sheets is further suppressed, and the appearance is improved. The adhesive strength (against glass plate, tensile speed 300 mm / min, peel angle 180 °) is larger than that of the (n-1) adhesive sheet (against PET film, tensile speed 300 mm / min, peel angle 180 °). It is preferable. Among them, the difference in adhesive strength [(adhesive strength to the glass (glass plate) in the nth adhesive sheet) − (adhesive strength to the polyethylene terephthalate film (PET form) in the (n−1) th adhesive sheet)] is 0. It is preferably 1 gf / 25 mm or more, more preferably 0.5 gf / 25 mm or more.

Further, the surface protective sheet of the present invention is more easily peelable while obtaining sufficient adhesion between the (n-1) th adhesive sheet and the nth adhesive sheet. When the n-1 pressure-sensitive adhesive sheet is peeled from the n-th pressure-sensitive adhesive sheet, the occurrence of “floating” or “peeling” between the pressure-sensitive adhesive sheets is further suppressed, and the appearance is improved. Adhesive strength (to aluminum plate, tensile speed 300 mm / min, peeling angle 180 °) is larger than that of the (n-1) adhesive sheet (against PET film, tensile speed 300 mm / min, peeling angle 180 °) It is preferable. In particular, the difference in adhesive strength [(adhesive strength to the aluminum (aluminum plate) in the nth adhesive sheet) − (adhesive strength to the polyethylene terephthalate film (PET form) in the (n−1) th adhesive sheet)] is 0. It is preferably 1 gf / 25 mm or more, more preferably 0.5 gf / 25 mm or more.

The surface protective sheet of the present invention is not particularly limited, but can be obtained by a known or common method. For example, a pressure-sensitive adhesive sheet having a base material layer and a pressure-sensitive adhesive layer can be prepared, and this pressure-sensitive adhesive sheet can be obtained by laminating n layers so that the base material layer and the pressure-sensitive adhesive layer are in contact with each other.

Since the surface protective sheet of the present invention has a structure in which n layers of pressure-sensitive adhesive sheets having a base material layer and a pressure-sensitive adhesive layer are laminated, the surface can be protected by sticking to an adherend. First, it can be protected with the first pressure-sensitive adhesive sheet, and then the second pressure-sensitive adhesive sheet is exposed by peeling off the first pressure-sensitive adhesive sheet, so that it can be protected with the second pressure-sensitive adhesive sheet. Thus, by peeling off one layer of the laminated pressure-sensitive adhesive sheet, the next-layer pressure-sensitive adhesive sheet is exposed, so that it can be continuously protected by the pressure-sensitive adhesive sheet. For example, when the first pressure-sensitive adhesive sheet is scratched or soiled by protection with the first pressure-sensitive adhesive sheet, the first pressure-sensitive adhesive sheet is peeled off and removed, so that the second The pressure-sensitive adhesive sheet is exposed and can be subsequently protected by this clean second pressure-sensitive adhesive sheet.

The surface protective sheet of the present invention is excellent in adhesion and easy peelability between pressure sensitive adhesive sheets, and is excellent in deterring “floating” and “peeling” between pressure sensitive adhesive sheets generated when the pressure sensitive adhesive sheet is peeled off. For this reason, the sheet for surface protection of this invention is excellent in the pick-up property of an adhesive sheet. Therefore, the surface protection sheet of the present invention can effectively protect the surface even if the adherend is thin and fragile.

Further, the surface protecting sheet of the present invention is excellent in appearance because it has excellent deterrence of “floating” and “peeling” between the pressure sensitive adhesive sheets generated when the pressure sensitive adhesive sheet is peeled off. In addition, when “floating” or “peeling” occurs, the appearance is adversely affected.

The surface protective sheet of the present invention is used for a wide range of applications. In particular, it is preferably used for electrical or electronic equipment applications (for example, surface protection application when manufacturing electrical or electronic equipment, surface protection use when using electrical or electronic equipment). Moreover, it is preferably used for optical applications (for example, surface protection applications during the production of optical products and optical members, and surface protection applications during the use of optical products and optical members).

Although it does not specifically limit as said electric equipment, For example, a refrigerator, a washing machine, an air-conditioning outdoor unit etc. are mentioned. The electronic device is not particularly limited, and examples thereof include an image display device such as a liquid crystal display and a plasma display, and a mobile device such as a notebook personal computer.
The area in contact with the nth adhesive sheet of the surface protecting sheet in these adherends of the surface protecting sheet is not particularly limited. For example, an area made of plastic, an area made of metal, and an area made of glass. Among them, the region made of glass is more preferable.

The optical product has optical characteristics (for example, polarization, light refraction, light scattering, light reflectivity, light transmission, light absorption, light diffraction, optical rotation, visibility, etc.) in the product. The product used. Examples of the optical products include display devices such as liquid crystal display devices, organic EL (electroluminescence) display devices, PDP (plasma display panels), and electronic paper, input devices such as touch panels, or these display devices and input devices. And the like may be used as appropriate.

The optical member refers to a member having the above optical characteristics. Examples of the optical member include a member constituting a device (optical device) such as the display device (image display device) and the input device, or a member used in these devices. , Retardation film, optical compensation film, brightness enhancement film, light guide plate, reflection film, antireflection film, transparent conductive film (ITO film), design film, decorative film, surface protection plate, prism, lens, color filter, transparent substrate In addition, members in which these are laminated (these may be collectively referred to as “optical films”) and the like may be mentioned. In addition, said "plate" and "film" shall include forms, such as plate shape, film shape, and sheet shape, respectively, for example, "polarizing film" shall include "polarizing plate" and "polarizing sheet". As described above, the “optical member” in the present invention is a member (design film, decorative film) that plays a role of decoration and protection while maintaining the visibility and excellent appearance of the display unit in the display device or the input device. And surface protective film).

The material constituting the optical member is not particularly limited, and examples thereof include glass, acrylic resin, polycarbonate, polyethylene terephthalate, and metal (including metal oxide).

(II) Structure The structure of the present invention has a configuration in which the surface protection sheet is provided on the surface of the member. Examples of the structure include a structure in which the surface protection sheet is provided on the surface of an electrical or electronic device, a structure in which the surface protection sheet is provided on the surface of an optical product, and the surface of an optical member. The structure etc. in which the said sheet | seat for surface protection is provided are mentioned. Specific examples of the electrical or electronic device, the optical product, and the optical member include those exemplified in the above-mentioned “(I) Surface protection sheet”.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the examples, unless otherwise indicated, parts by weight means a value converted to solid content.

(Usage example 1 of base material)
As a base material constituting the base material layer, a PET film (thickness: 25 μm, trade name “T100-25”, manufactured by Mitsubishi Plastics, Inc.) was used.
This PET film was referred to as “base material (A)”.

(Usage example 2)
As a base material constituting the base material layer, a PET film (thickness: 75 μm, trade name “T100-75”, manufactured by Mitsubishi Plastics, Inc.) was used.
This PET film was designated as “base material (B)”.

(Usage example 3)
A PET film (thickness: 38 μm, trade name “T100-638”, manufactured by Mitsubishi Plastics, Inc.) was used as a base material constituting the base material layer.
This PET film was referred to as “base material (C)”.

(Usage example 4)
As a base material constituting the base material layer, a PET film (thickness: 125 μm, trade name “Lumirror # 125S10”, manufactured by Toray Industries, Inc.) was used.
This PET film was designated as “base material (D)”.

(Preparation Example 1 of pressure-sensitive adhesive composition)
Addition reaction type silicone adhesive (trade name “X-40-3306”, manufactured by Shin-Etsu Chemical Co., Ltd.): 100 parts by weight and platinum-based catalyst (trade name “CAT-PL-50T”, manufactured by Shin-Etsu Chemical Co., Ltd.) ): 0.2 part by weight was mixed to obtain a silicone-based pressure-sensitive adhesive composition.
This silicone pressure-sensitive adhesive composition was referred to as “pressure-sensitive adhesive composition (A)”.

(Preparation example 2 of pressure-sensitive adhesive composition)
As monomer components, butyl acrylate: 90 parts by weight, acrylic acid: 10 parts by weight, and ethyl acetate: 150 parts by weight as a polymerization solvent were put into a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature was raised to 63 ° C., and 2,2′-azobisisobutyronitrile as a polymerization initiator: 0.2 part by weight was added and reacted for 10 hours. Then, methyl ethyl ketone was added to obtain an acrylic polymer solution having a solid concentration of 25% by weight. The weight average molecular weight of the acrylic polymer in the acrylic polymer was 650,000.
A crosslinking agent (trade name “Tetrad C”, Mitsubishi Gas Chemical Co., Inc., epoxy crosslinking agent) is added to the acrylic polymer solution so as to be 11 parts by weight with respect to 100 parts by weight of the acrylic polymer. A pressure-sensitive adhesive composition was obtained.
This acrylic pressure-sensitive adhesive composition was designated as “pressure-sensitive adhesive composition (B)”.

(Preparation Example 3 of pressure-sensitive adhesive composition)
As monomer components, 2-ethylhexyl acrylate: 100 parts by weight, 2-hydroxyethyl acrylate: 4 parts by weight, and ethyl acetate as a polymerization solvent: 150 parts by weight were introduced into a separable flask, and nitrogen gas was introduced. The mixture was stirred for 1 hour. After removing oxygen in the polymerization system in this way, the temperature was raised to 63 ° C., and 2,2′-azobisisobutyronitrile as a polymerization initiator: 0.2 part by weight was added and reacted for 10 hours. Then, methyl ethyl ketone was added to obtain an acrylic polymer solution having a solid concentration of 25% by weight. The weight average molecular weight of the acrylic polymer in the acrylic polymer was 550,000.
To the acrylic polymer solution, a crosslinking agent (trade name “Coronate HX”, Nippon Polyurethane Industry Co., Ltd., isocyanate crosslinking agent) is added to 4 parts by weight with respect to 100 parts by weight of the acrylic polymer, Dioctyltin dilaurate (trade name “OL-1”, manufactured by Tokyo Fine Chemical Co., Ltd.) was added in an amount of 0.015 parts by weight with respect to 100 parts by weight of the acrylic polymer to obtain an acrylic pressure-sensitive adhesive composition.
This acrylic pressure-sensitive adhesive composition was designated as “pressure-sensitive adhesive composition (C)”.

(Usage example 1 of release liner)
The trade name “Diafoil MRF-25” (manufactured by Mitsubishi Plastics, polyester film, thickness: 25 μm) was used as the release liner.
This release liner was designated as “release liner (A)”.

Example 1
The pressure-sensitive adhesive composition (A) was applied to one surface of the substrate (A) and dried at 130 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 10 μm. And the release liner (A) was provided on the adhesive layer. Thus, the 1st adhesive sheet was obtained. The first pressure-sensitive adhesive sheet has a laminated structure of base material (A) / pressure-sensitive adhesive layer / release liner (A).
Next, the pressure-sensitive adhesive composition (A) was applied to one surface of the substrate (B) and dried at 130 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 75 μm. And the release liner (A) was provided on the adhesive layer. In this way, a second pressure-sensitive adhesive sheet was obtained. The second pressure-sensitive adhesive sheet has a laminated structure of base material (B) / pressure-sensitive adhesive layer / release liner (A).
Then, the pressure-sensitive adhesive surface exposed by peeling off the release liner (A) of the first pressure-sensitive adhesive sheet was bonded to the surface provided by the base material (B) of the second pressure-sensitive adhesive sheet to obtain a laminated pressure-sensitive adhesive sheet. This laminated pressure-sensitive adhesive sheet has a laminated structure of first pressure-sensitive adhesive sheet / second pressure-sensitive adhesive sheet / release liner (A).

Example 2
The pressure-sensitive adhesive composition (A) was applied to one surface of the substrate (A) and dried at 130 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 10 μm. And the release liner (A) was provided on the adhesive layer. Thus, the 1st adhesive sheet was obtained. The first pressure-sensitive adhesive sheet has a laminated structure of base material (A) / pressure-sensitive adhesive layer / release liner (A).
Next, the pressure-sensitive adhesive composition (C) was applied to one surface of the substrate (C) and dried at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 21 μm. And the release liner (A) was provided on the adhesive layer. In this way, a second pressure-sensitive adhesive sheet was obtained. The second pressure-sensitive adhesive sheet has a laminated structure of base material (C) / pressure-sensitive adhesive layer / release liner (A).
Then, the pressure-sensitive adhesive surface exposed by peeling off the release liner (A) of the first pressure-sensitive adhesive sheet was bonded to the surface provided by the base material (C) of the second pressure-sensitive adhesive sheet to obtain a laminated pressure-sensitive adhesive sheet. This laminated pressure-sensitive adhesive sheet has a laminated structure of first pressure-sensitive adhesive sheet / second pressure-sensitive adhesive sheet / release liner (A).

Example 3
The pressure-sensitive adhesive composition (A) was applied to one surface of the substrate (A) and dried at 130 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 10 μm. And the release liner (A) was provided on the adhesive layer. Thus, the 1st adhesive sheet was obtained. The first pressure-sensitive adhesive sheet has a laminated structure of base material (A) / pressure-sensitive adhesive layer / release liner (A).
Next, the pressure-sensitive adhesive composition (B) was applied to one surface of the substrate (D) and dried at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 20 μm. And the release liner (A) was provided on the adhesive layer. In this way, a second pressure-sensitive adhesive sheet was obtained. The second pressure-sensitive adhesive sheet has a laminated structure of base material (D) / pressure-sensitive adhesive layer / release liner (A).
And the adhesive surface which peeled and peeled the release liner (A) of the said 1st adhesive sheet was bonded together to the surface provided by the base material (D) of a 2nd adhesive sheet, and the laminated adhesive sheet was obtained. This laminated pressure-sensitive adhesive sheet has a laminated structure of first pressure-sensitive adhesive sheet / second pressure-sensitive adhesive sheet / release liner (A).

Comparative Example 1
The pressure-sensitive adhesive composition (C) was applied to one surface of the substrate (C) and dried at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 21 μm. And the release liner (A) was provided on the adhesive layer. Thus, the 1st adhesive sheet was obtained. The first pressure-sensitive adhesive sheet has a laminated structure of base material (C) / pressure-sensitive adhesive layer / release liner (A).
Next, the pressure-sensitive adhesive composition (C) was applied to one surface of the substrate (C) and dried at 130 ° C. for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 21 μm. And the release liner (A) was provided on the adhesive layer. In this way, a second pressure-sensitive adhesive sheet was obtained. The second pressure-sensitive adhesive sheet has a laminated structure of base material (C) / pressure-sensitive adhesive layer / release liner (A).
Then, the pressure-sensitive adhesive surface exposed by peeling off the release liner (A) of the first pressure-sensitive adhesive sheet was bonded to the surface provided by the base material (C) of the second pressure-sensitive adhesive sheet to obtain a laminated pressure-sensitive adhesive sheet. This laminated pressure-sensitive adhesive sheet has a laminated structure of first pressure-sensitive adhesive sheet / second pressure-sensitive adhesive sheet / release liner (A).

Comparative Example 2
The pressure-sensitive adhesive composition (A) was applied to one surface of the substrate (B) and dried at 130 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 75 μm. And the release liner (A) was provided on the adhesive layer. Thus, the 1st adhesive sheet was obtained. The first pressure-sensitive adhesive sheet has a laminated structure of base material (B) / pressure-sensitive adhesive layer / release liner (A).
Next, the pressure-sensitive adhesive composition (A) was applied to one surface of the substrate (A) and dried at 130 ° C. for 3 minutes to form a pressure-sensitive adhesive layer having a thickness of 10 μm. And the release liner (A) was provided on the adhesive layer. In this way, a second pressure-sensitive adhesive sheet was obtained. The second pressure-sensitive adhesive sheet has a laminated structure of base material (A) / pressure-sensitive adhesive layer / release liner (A).
And the adhesive surface which peeled and peeled the release liner (A) of the said 1st adhesive sheet was bonded together to the surface provided by the base material (A) of a 2nd adhesive sheet, and the laminated adhesive sheet was obtained. This laminated pressure-sensitive adhesive sheet has a laminated structure of first pressure-sensitive adhesive sheet / second pressure-sensitive adhesive sheet / release liner (A).

(Evaluation)
About the Example and the comparative example, the following measurement or evaluation was performed. The results are shown in Table 1.

(Measurement of deflection)
The amount of deflection of the pressure-sensitive adhesive sheet was determined according to the above [Method of measuring the amount of deflection].

(Measurement of adhesive strength)
A pressure-sensitive adhesive sheet (first pressure-sensitive adhesive sheet or second pressure-sensitive adhesive sheet) was cut into a sheet having a width of 20 mm and a length of 100 mm to obtain a test piece.
Next, the adhesive surface (measurement surface) of the test piece was pressed against a sheet-like adherend by reciprocating a 2 kg roller, and aged for 30 minutes in an atmosphere of 23 ° C. and 50% RH. Then, using a universal tensile and compression tester (device name “Tensile and compression tester TG-1kN”, manufactured by Minebea Co., Ltd.), an atmosphere of 23 ° C. and 50% RH, a tensile speed of 300 mm / min, and a peeling angle of 180 ° Under the conditions, the test piece was peeled off from the adherend, and the adhesive strength (180 ° peel adhesive strength) (gf / 25 mm) was measured.
As an adherend, a PET film, a glass plate (trade name “Micro Slide Glass S”, manufactured by Matsunami Glass Industrial Co., Ltd., using a non-tin surface), and an aluminum plate (trade name “A1050P (matte)”), Nippon Test Panel Co., Ltd.) was used.

(Evaluation of pickup properties)
The release liner (A) of the laminated pressure-sensitive adhesive sheet is peeled off, the pressure-sensitive adhesive surface of the second pressure-sensitive adhesive sheet is exposed, and a 2 kg roller is reciprocated once to pressure-bond to a sheet-like adherend (aluminum plate). Aging was performed for 30 minutes in an atmosphere of 50 ° C. and 50% RH. Thereafter, the first pressure-sensitive adhesive sheet was picked up by using a pickup tape (trade name “BT-315ST”, manufactured by Nitto Denko Corporation).
The state at the time of this pickup was observed and evaluated according to the following criteria.
Evaluation criteria Good (O): When the first pressure-sensitive adhesive sheet can be easily peeled from the second pressure-sensitive adhesive sheet, and there is no “floating” or “peeling” between the adherend and the second pressure-sensitive adhesive sheet Defect (x): When the above condition is not satisfied (for example, when the first pressure-sensitive adhesive sheet cannot be easily peeled from the second pressure-sensitive adhesive sheet, when the first pressure-sensitive adhesive sheet cannot be peeled from the second pressure-sensitive adhesive sheet, the second When the first pressure-sensitive adhesive sheet is peeled from the first pressure-sensitive adhesive sheet, "floating" or "peeling" occurs between the adherend and the second pressure-sensitive adhesive sheet)

For the laminated pressure-sensitive adhesive sheet of the example, the release liner (A) was first peeled from the second pressure-sensitive adhesive sheet when evaluating the pickup property. At this time, “floating” or “peeling” did not occur between the first pressure-sensitive adhesive sheet and the second pressure-sensitive adhesive sheet. Moreover, the release liner (A) could be peeled off smoothly without causing damage to the adhesive layer.

From the evaluation of the above pick-up property, it was possible to easily peel off the first pressure-sensitive adhesive sheet from the second pressure-sensitive adhesive sheet for the laminated pressure-sensitive adhesive sheet of the example. The laminated pressure-sensitive adhesive sheets of the examples are excellent in appearance and design.

The surface protective sheet of the present invention is used for a wide range of applications. In particular, it is preferably used for electrical or electronic equipment. Moreover, it is preferably used for optical applications.

X Surface protection sheet X
Y Surface protection sheet Y
Z Surface protection sheet Z
DESCRIPTION OF SYMBOLS 1 1st adhesive sheet 2 2nd adhesive sheet 3 3rd adhesive sheet n-1 (n-1) adhesive sheet n nth adhesive sheet 11 Base material layer 12 Adhesive layer 13 Release liner 41 Support stand 42 Adhesive sheet 421 Overhang part of adhesive sheet f Deflection amount (deflection distance, sagging distance)

Claims (8)

1. A sheet for surface protection comprising a base material layer and a pressure-sensitive adhesive layer, wherein the first to n (n is an integer of 2 or more) pressure-sensitive adhesive sheets are laminated in that order in n layers,
   The adhesive layers of the first to (n-1) adhesive sheets are in contact with the base material layers of the second to n adhesive sheets, respectively.
   The amount of deflection defined below of the first to (n-1) pressure-sensitive adhesive sheets is the amount of deflection defined below of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet. The sheet for surface protection characterized by being larger than each.
   Deflection amount (mm): A pressure sensitive adhesive sheet having a width of 20 mm and a length of 10 cm is fixed to a support base so that the protruding portion is a sheet having a width of 20 mm and a length of 8 cm, and then at 23 ° C. for 1 minute. It is determined by measuring the distance in the vertical direction from the original position of the free end of the overhanging portion of the adhesive sheet.
2. The difference between the deflection amount of the first to (n-1) adhesive sheets and the deflection amount of the second to n adhesive sheets adjacent to and in contact with the adhesive layer side of the adhesive sheet is 1.0 mm or more, respectively. The surface protective sheet according to claim 1.
3. 3. The surface protecting material according to claim 1, wherein the thickness of the first to (n-1) pressure-sensitive adhesive sheets is smaller than the thickness of each of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet. Sheet.
4. A sheet for surface protection comprising a base material layer and a pressure-sensitive adhesive layer, wherein the first to n (n is an integer of 2 or more) pressure-sensitive adhesive sheets are laminated in that order in n layers,
   The adhesive layers of the first to (n-1) adhesive sheets are in contact with the base material layers of the second to n adhesive sheets, respectively.
   The base material layers of the first to n-th adhesive sheets are the same,
   The composition of the pressure-sensitive adhesive layer of the first to n-th pressure-sensitive adhesive sheets is common,
   The surface protective sheet, wherein the thickness of the first to (n-1) pressure-sensitive adhesive sheets is smaller than the thickness of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet.
5. The difference between the thickness of the first to (n-1) pressure-sensitive adhesive sheets and the thickness of the second to n-th pressure-sensitive adhesive sheets adjacent to and in contact with the pressure-sensitive adhesive layer side of the pressure-sensitive adhesive sheet is more than 0 and 500 μm or less. The surface protecting sheet according to any one of claims 1 to 4, wherein the sheet is for protecting a surface.
6. Having a release liner on the pressure-sensitive adhesive layer of the nth pressure-sensitive adhesive sheet,
   The relationship between the thickness of the release liner, the thickness of the (n-1) th adhesive sheet and the thickness of the nth adhesive sheet is as follows:
   (Thickness of the release liner) <(thickness of the (n-1) th adhesive sheet) <(thickness of the nth adhesive sheet)
   The surface protecting sheet according to any one of claims 1 to 5, wherein
7. Having a release liner on the pressure-sensitive adhesive layer of the nth pressure-sensitive adhesive sheet,
   The surface protective sheet according to any one of claims 1 to 6, wherein the release liner has a thickness of 10 to 50 袖 m.
8. A structure having the surface protective sheet according to any one of claims 1 to 7 on a surface of a member.

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