KR20170076584A - Adhesive sheet for graphite sheet - Google Patents

Abstract

A pressure-sensitive adhesive sheet for a graphite sheet having excellent appearance and improved detection accuracy of defects and the like is provided. According to the present invention, there is provided a single-sided adhesive pressure-sensitive adhesive sheet used by attaching to a graphite sheet. The pressure-sensitive adhesive sheet comprises a base material and a pressure-sensitive adhesive layer formed on one surface of the base material. The substrate contains a black layer. The gloss value of 60 deg. Of the back surface of the pressure sensitive adhesive sheet is 10 or less. Further, the light transmittance of the adhesive sheet is 12 to 30%.

Description

 [0001] ADHESIVE SHEET FOR GRAPHITE SHEET [0002]

The present invention relates to a pressure-sensitive adhesive sheet for a graphite sheet.

The present application claims priority based on Japanese Patent Application No. 2015-252606, filed on December 24, 2015, the entire contents of which are incorporated herein by reference.

In general, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive, hereinafter the same) shows a state of a soft solid (viscoelastic material) in a temperature region near room temperature and has a property of simply adhering to an adherend by pressure. Taking advantage of these properties, the pressure-sensitive adhesive is widely used in the form of a pressure-sensitive adhesive sheet having a substrate for the purpose of bonding, fixing, and protecting various members. For example, in a portable electronic device such as a cellular phone, a pressure-sensitive adhesive sheet having the above-described configuration is used for the purpose of protecting a graphite sheet provided for heat radiation and imparting designability. Specifically, the pressure-sensitive adhesive sheet for this application has a constitution in which a pressure-sensitive adhesive layer is disposed on one side of a substrate having a colored layer formed thereon.

Japanese Patent Application Laid-Open No. 2013-203965

The pressure-sensitive adhesive sheet on which the colored layer is formed is usually required to have a predetermined appearance depending on its attachment point or the like. For example, in a pressure-sensitive adhesive sheet used in a portable electronic device, a black coloring layer is preferably employed from the viewpoint of harmony and texture with peripheral members. It is also desired that the pressure sensitive adhesive sheet adhered to the graphite sheet has a light transmittance sufficient to confirm the presence or absence of defects or foreign matter in the graphite sheet as an adhesive over the pressure sensitive adhesive sheet. Specifically, for example, in Patent Document 1, a visual inspection over an adhesive sheet using a light box is performed by setting the light transmittance of the colored base material constituting the adhesive sheet within a range of 0.4 to 8%. However, in the structure of Patent Document 1, since the light transmittance is set to a low value, a white defect (such as leakage of white light from a pin hole) or foreign matter, a dark defect, or the like And the detection accuracy is not sufficient in applications where the level of demand for the quality of the adherend is high. Further, when the back surface of the pressure-sensitive adhesive sheet has gloss, detection accuracy may be lowered by gloss (reflected light). It is advantageous to improve the detection precision of defects and the like without sacrificing appearance.

An object of the present invention is to provide a pressure-sensitive adhesive sheet for a graphite sheet, which has been produced in view of the above-described circumstances, has excellent appearance and is improved in detection accuracy of defects and the like.

According to the present invention, there is provided a single-sided adhesive pressure-sensitive adhesive sheet used by attaching to a graphite sheet. The pressure-sensitive adhesive sheet comprises a base material and a pressure-sensitive adhesive layer formed on one surface of the base material. The substrate contains a black layer. In addition, the 60 ° gloss value of the back surface of the pressure-sensitive adhesive sheet is 10 or less. Further, the light transmittance of the adhesive sheet is 12 to 30%.

According to the above configuration, since the light transmittance of the pressure sensitive adhesive sheet is set within the range of 12 to 30%, the detection accuracy of the defect or the like of the graphite sheet performed over the pressure sensitive adhesive sheet is improved. In particular, there is a tendency that the detectability of defects such as whiteness or blackness or foreign matter (hereinafter also referred to simply as defects) tends to be excellent. Further, since the gloss of the back surface of the pressure-sensitive adhesive sheet is suppressed, adverse effects on the inspection due to the reflected light on the back surface of the pressure-sensitive adhesive sheet are suppressed. In addition, since the light transmittance of the pressure sensitive adhesive sheet is set in the above-described range, the color feeling of the graphite sheet to be adhered is appropriately reflected (appropriately), and an appearance having a desired color and texture is obtained. Further, since the gloss value of 60 ° is limited to 10 or less, a black color with a luster of which is suppressed, as well as the black layer, is imparted to the back surface of the adhesive sheet, and the appearance of the graphite sheet and its peripheral members Is created. Thus, according to the present invention, a pressure-sensitive adhesive sheet for a graphite sheet having an excellent appearance when attached to a graphite sheet and having improved detection accuracy of defects is realized.

In one preferred form of the pressure sensitive adhesive sheet disclosed herein, the base material comprises a resin film layer and a black layer. Further, the pressure-sensitive adhesive sheet has the pressure-sensitive adhesive layer, the resin film layer and the black layer laminated in this order. By such a constitution, a pressure-sensitive adhesive sheet having excellent appearance and excellent in detectability of defects and the like is preferably realized.

In one preferred form of the pressure-sensitive adhesive sheet disclosed herein, the thickness of the black layer is 2 탆 or less. The effect of the technique disclosed here is preferably realized with a structure having the black layer of such a thin thickness as described above. Further, by limiting the thickness of the black layer, it is possible to suppress the thickness increase of the pressure-sensitive adhesive sheet. This can be a desirable feature in applications requiring thinning and weight reduction.

In a preferred form of the pressure-sensitive adhesive sheet disclosed herein, the back surface of the pressure-sensitive adhesive sheet has a brightness L ^* defined by the L ^* a ^* b ^* colorimetric system of 40 or less. By such a constitution, an excellent appearance is preferably realized.

In a preferred form of the pressure sensitive adhesive sheet disclosed herein, the substrate further comprises a mat layer. Further, the substrate has a laminated structure in which the resin film layer, the black layer and the mat layer are laminated in this order. By such a constitution, a configuration having a predetermined gloss value and a light transmittance is preferably realized.

In a preferred form of the pressure-sensitive adhesive sheet disclosed herein, the mat layer contains a particulate mat member. By such a constitution, the low gloss of the back surface of the pressure-sensitive adhesive sheet is preferably realized.

In a preferred form of the pressure-sensitive adhesive sheet disclosed herein, the thickness of the mat layer is 2 탆 or less. By such a constitution, the desired appearance can be improved while suppressing the thickness increase of the pressure-sensitive adhesive sheet. This can be a desirable feature in applications requiring thinning and weight reduction.

In a preferred form of the pressure-sensitive adhesive sheet disclosed herein, the total thickness of the pressure-sensitive adhesive sheet is 30 占 퐉 or less. In such a thin pressure-sensitive adhesive sheet, the effect of the technique disclosed herein is preferably realized.

According to the present invention, there is also provided a pressure-sensitive adhesive sheet with a release liner comprising any of the pressure-sensitive adhesive sheets disclosed herein and a release liner for protecting the adhesive surface of the pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet comprises a base material and a pressure-sensitive adhesive layer formed on one surface of the base material. The substrate contains a black layer. The gloss value of 60 deg. Of the back surface of the pressure sensitive adhesive sheet is 10 or less. Further, the light transmittance of the adhesive sheet is 12 to 30%.

The pressure-sensitive adhesive sheet for a graphite sheet disclosed here is excellent in appearance and has improved detection accuracy of defects and the like. Taking advantage of this feature, it is suitable as a pressure-sensitive adhesive sheet for use in a graphite sheet disposed in a portable electronic device such as a cellular phone or a smart phone. Accordingly, the adhesive sheet provided by this specification may be laminated on a graphite sheet disposed in a portable electronic device.

1 is a cross-sectional view schematically showing an example of a configuration of a pressure-sensitive adhesive sheet.

Hereinafter, preferred embodiments of the present invention will be described. The matters necessary for carrying out the present invention may be understood by those skilled in the art based on the teachings of the present invention and the technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the technical knowledge in the related art. In the following drawings, the same parts are denoted by the same reference numerals, and redundant descriptions may be omitted or simplified. It should be noted that the embodiments shown in the drawings are schematized to clearly illustrate the present invention, and the size and scale of the pressure-sensitive adhesive sheet of the present invention actually provided as an article are not always accurately shown.

As used herein, the term " pressure-sensitive adhesive " refers to a material that exhibits a soft solid state (viscoelastic body) in a temperature region near room temperature and has a property of being easily adhered to an adherend by pressure. The pressure-sensitive adhesive referred to herein generally has a complex tensile modulus E ^* (1 Hz) < 1 >, as defined in CA Dahlquist, "Adhesion: Fundamental and Practice", McLaren & Sons 10 < ⁷ > dyne / cm < ² > (typically, a material having the above properties at 25 DEG C).

<Constitution of Adhesive Sheet>

The pressure-sensitive adhesive sheet disclosed herein is a one-sided adhesive pressure-sensitive adhesive sheet having a substrate having a pressure-sensitive adhesive layer on one surface of a substrate (support). The concept of the adhesive sheet referred to herein may include what is referred to as an adhesive tape, an adhesive label, an adhesive film, or the like. The pressure sensitive adhesive sheet disclosed herein may be in the form of a roll or a sheet. Alternatively, the pressure-sensitive adhesive sheet may be further processed into various shapes.

The pressure-sensitive adhesive sheet disclosed herein may be, for example, one having a sectional structure schematically shown in Fig. The adhesive sheet 1 shown in Fig. 1 has a sheet-like base material 10 and a pressure-sensitive adhesive layer 20 formed on one surface 10A of the base material 10. Fig. In addition, the base material 10 has a resin film layer 12 and a black layer 14. In this embodiment, the pressure sensitive adhesive layer 20 is formed on the first surface 12A of the resin film layer 12, and the black layer 14 is formed on the second surface 12B of the resin film layer 12 . Further, the substrate 10 further comprises a matte layer 16. The base material 10 has a laminated structure in which a resin film layer 12, a black layer 14 and a matte layer 16 are laminated in this order. In this embodiment, the matte layer 16 is the outermost layer of the base material 10, and the outer surface 16A of the matte layer 16 is the back surface 1B of the adhesive sheet 1. [ In this pressure-sensitive adhesive sheet 1, the surface of the pressure-sensitive adhesive layer 20 is the adhesive surface 1A of the pressure-sensitive adhesive sheet 1.

The adhesive sheet 1 before use has a constitution in which the adhesive layer 20 is protected by the release liner 50 whose side of the adhesive layer 20 is the release side 50B. The outer surface 50A of the release liner 50 (the release surface 50B) of the release liner 50 is formed in the form of a roll (adhesive sheet roll) for the purpose of transporting, And the back surface 1B (the outer surface 16A of the matte layer 16 in the present embodiment) of the adhesive sheet can be brought into contact with each other.

In the above embodiment, the base material 10 has a laminated structure of the resin film layer 12, the black layer 14, and the matte layer 16, but is not limited thereto. For example, the mat layer may be omitted. In this case, the 60 ° gloss value of the back surface of the pressure-sensitive adhesive sheet can be made 10 or less by making the base material have a laminated structure composed of the resin film layer and the black layer and performing matting treatment on the back surface thereof. Further, for example, when the base material has the resin film layer and the black layer, the black layer may be arranged on the pressure-sensitive adhesive layer side rather than the resin film layer, unlike the above embodiment. In this case, the pressure-sensitive adhesive sheet has a laminate structure in which a pressure-sensitive adhesive layer, a black layer, a resin film layer and a mat layer (optional) are laminated in this order. Alternatively, the substrate may be composed of only a black layer. In this case, the base material can have both the strength of the resin film layer and the color of the black layer.

<Properties of Adhesive Sheet>

The 60 DEG gloss value of the back surface of the pressure sensitive adhesive sheet disclosed herein is 10 or less. As a result, the adverse effect of the reflected light on the back surface of the pressure-sensitive adhesive sheet is suppressed, and the testability of the graphite sheet is improved. Further, by such low glossing, in addition to the black layer, the back surface of the pressure sensitive adhesive sheet can exhibit a black color full of feeling of being suppressed in glossiness. The 60 占 gloss value of the back surface of the pressure-sensitive adhesive sheet is more preferably 7 or less, further preferably 6 or less (typically 5.5 or less). The lower limit value of the 60 DEG gloss value is not particularly limited, but is preferably at least 1, more preferably at least 2 (for example, at least 3, and typically at least 3.5) from the balance of design and color. The gloss value is obtained by forming a mat layer on the back side of the pressure-sensitive adhesive sheet, or performing a mat treatment (surface treatment) such as embossing or sandblasting.

The gloss value of 60 ° on the back surface of the adhesive sheet was measured using a commercially available gloss meter (for example, trade name "gloss glosser IG-410" manufactured by Horiba Seisakusho Co., Ltd.) do. This also applies to the following embodiments.

The light transmittance of the pressure-sensitive adhesive sheet disclosed here is 12 to 30%. This improves the detection accuracy of defects (particularly, whiteness or blackness defects or foreign matter) of the graphite sheet carried over the pressure-sensitive adhesive sheet. Further, by setting the light transmittance of the pressure-sensitive adhesive sheet within the above-mentioned range, the color tone of the graphite sheet to be adhered is appropriately reflected, and excellent color and texture can be obtained. The light transmittance is preferably 25% or less, more preferably 20% or less, further preferably 18% or less. The light transmittance is preferably at least 14%, more preferably at least 15% (for example, at least 16%). From the viewpoint of obtaining excellent appearance (color, texture, etc.), the light transmittance can be adjusted according to the content and thickness of the colorant in the black layer and the number of layers in the sublayer.

The light transmittance of the adhesive sheet is obtained by irradiating light having a wavelength of 380 to 780 nm vertically to one surface of the adhesive sheet using a commercially available spectrophotometer and measuring the intensity of the light transmitted to the other surface. As the spectrophotometer, for example, a spectrophotometer (apparatus name: U4100 type spectrophotometer) of Hitachi Seisakusho Co., Ltd. can be used. This also applies to the following embodiments.

In a preferred form, the back surface of the pressure-sensitive adhesive sheet may have a lightness L ^* defined by the L ^* a ^* b ^* colorimetric system of 50 or less (for example, 40 or less, typically 35 or less). The lightness L ^* is preferably 30 or less. The pressure-sensitive adhesive sheet having the lightness is preferably used for a purpose of adhering to a graphite sheet in which black is desired. The pressure-sensitive adhesive sheet having the above-mentioned back surface exhibits a black color with a luster suppressed and full of dazzling feeling, and can be colored with a good harmony with its surrounding members (for example, batteries) by being laminated on a graphite sheet. The lower limit of the lightness L ^* is not particularly limited, but may be set to about 15 or more (for example, 20 or more) from the viewpoint of appearance and the like.

The chromaticity a ^* defined by the L ^* a ^* b ^* color system of the back surface of the pressure sensitive adhesive sheet is not particularly limited, but may be within a range of ± 15 (for example, For example, +/- 5, typically +/- 2). The chromaticity b ^* is not particularly limited, but is preferably in the range of ± 15 (for example, ± 10, typically ± 5). In the present specification, "range of ± X" is used in the meaning of a range of -X to + X.

In addition, the L ^* a ^* b ^* color system in this specification shall conform to the regulations recommended by the International Lighting Commission in 1976 or the provisions of JIS Z 8729. Specifically, L ^* a ^* b ^* is measured at a plurality of places (for example, five points or more) with respect to the back surface of the pressure sensitive adhesive sheet by using a color difference meter (trade name: CR-400, Minolta Co., And the average value is adopted. This also applies to the following embodiments.

The pressure-sensitive adhesive sheet disclosed herein preferably has a 180 degree peel strength of 0.5 N / 20 mm or more. The pressure sensitive adhesive sheet exhibiting the above characteristics can be favorably adhered to the graphite sheet as the adherend. The peel strength is more preferably 1.0 N / 20 mm or more, and still more preferably 2.0 N / 20 mm or more. Here, the peel strength refers to the 180-degree peel strength (180-degree peel adhesion strength) of a stainless steel plate.

The 180 degree peel strength can be measured as follows. Specifically, a single-sided pressure-sensitive adhesive tape (trade name: "No.31B" manufactured by Nitto Denko Co., Ltd., total thickness of 50 μm) was attached to the back surface of the pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive sheet was cut into a measurement sample having a width of 20 mm and a length of 100 mm Under the environment of 23 占 폚 and 50% RH, the adhesion surface of the measurement sample is pressed and bonded to the surface of a stainless steel plate (SUS304BA plate) with one reciprocation of 2 kg roller. This is left for 30 minutes under the same environment, and then the peel strength (N / 20 mm) is measured in accordance with JIS Z0237: 2000 at a tensile speed of 300 mm / min and a peel angle of 180 degrees using a universal tensile compression tester. As the universal tensile compression testing machine, for example, a &quot; tensile compression testing machine, TG-1kN &quot; This is also measured in the following examples.

The total thickness of the pressure-sensitive adhesive sheet (including the pressure-sensitive adhesive layer and the substrate, but not including the release liner) disclosed herein is not particularly limited and is suitably about 2 占 퐉 or more (for example, 3 占 퐉 or more) It is also appropriate that the thickness is approximately 150 mu m or less (for example, 100 mu m or less, typically 50 mu m or less). The total thickness of the pressure-sensitive adhesive sheet according to a preferred embodiment may be about 30 탆 or less (for example, 20 탆 or less, typically 10 탆 or less) and the total thickness may be 7 탆 or less. The thin pressure sensitive adhesive sheet may be advantageous in terms of thinning, miniaturization, light weight, resource saving, and the like of a product to which the pressure sensitive adhesive sheet is applied. Further, by forming the pressure-sensitive adhesive sheet described herein to have a thin thickness, the heat radiating effect of the graphite sheet is sufficiently exhibited.

<Description>

(Composition of substrate)

The substrate disclosed herein contains a black layer. In addition, the substrate relating to a preferred embodiment may be one having a resin film layer and a black layer, and further comprising a mat layer. In particular, a substrate having a laminated structure in which a resin film layer, a black layer and a mat layer are laminated in this order is particularly preferable as in the above embodiment. This laminated structure may be an optimal structure for realizing the effect of the technique disclosed herein. Further, in another preferred embodiment, the substrate may be composed of only a black layer. Thus, the substrate disclosed herein may have a single-layer structure, a two-layer structure, or a multi-layer structure of three or more layers.

(Black layer)

The black layer disclosed here includes the entirety of the black layer, and usually refers to a layer containing a black colorant. For example, a layer having a surface having a brightness L ^* defined by the above-described L ^* a ^* b ^* colorimetric system of not more than 40 (for example, not more than 35, typically not more than 30) This is a typical example. Since the base material contains a black layer, excellent appearance is obtained when laminated on a graphite sheet, in addition to a light transmittance and a low gloss value. The black layer relating to a preferred form is a black print layer printed on the surface (first surface or second surface) of a resin film layer described later. From the viewpoint of appearance and the like, it is preferable that the black layer is formed on the second surface (surface opposite to the pressure-sensitive adhesive layer side surface) of the resin film layer. In another preferred form, the black layer may be a black colored resin film layer to be described later. In this case, the substrate may be composed of only a black layer.

In a preferred form, the black layer can be formed by applying a composition for forming a black layer containing a black coloring agent and a binder to a resin film layer described later. As the binder, materials known in the paint or printing field can be used without particular limitation. Examples of such a material include polyurethane, phenol resin, epoxy resin, urea melamine resin, polymethyl methacrylate, and the like. The black layer-forming composition may be, for example, a solvent type, an ultraviolet ray hardening type, a heat hardening type or the like. The formation of the black layer can be carried out by employing means conventionally used for forming the black layer without any particular limitation. For example, a method of forming a black layer (black print layer) by printing such as gravure printing, flexo printing, and offset printing can be preferably employed. Among them, gravure printing is particularly preferable. By controlling the plate of the gravure printing, the color feeling of the black layer can be relatively easily adjusted.

The black layer may be a single layer structure having a single layer as a whole or a multi-layer structure containing two layers, three layers or more sub-layers. When the black layer has a multilayer structure, it is preferable that at least one sublayer (preferably all sublayers) is a black layer (sub-black layer). The multi-layered black layer containing two or more sub-layers can be formed, for example, by repeatedly applying (for example, printing) the composition for forming a black layer. The types and blending amounts of the colorants contained in each sub-layer may be the same or different.

As the black coloring agent used for coloring the black layer, an organic or inorganic coloring agent (pigment, dye, etc.) may be used. Specific examples of the black coloring agent include carbon black, acetylene black, graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, iron oxide, molybdenum disulfide, Anthraquinone type coloring agents and the like. Among them, carbon black is preferable. The black colorant may be used alone or in combination of two or more. Although not particularly limited, it is preferable to use, for example, carbon black having an average particle diameter of 10 nm to 500 nm (more preferably 10 nm to 120 nm). The term &quot; average particle diameter &quot; in the present specification means, unless otherwise specified, a particle size at an integrated value of 50% in a particle size distribution measured on the basis of a particle size distribution measuring apparatus based on a laser scattering / Average particle diameter; hereinafter, sometimes abbreviated as D ₅₀ ).

The content of the black coloring agent is not limited to a specific range because it is set in accordance with the required color and texture, but it is preferably at least 1% by weight in the black layer, more preferably at least 2% by weight , At least 5 wt%, typically at least 15 wt%). The content of the black coloring agent in the black layer is suitably about 65% by weight or less, and from the viewpoint of the testability, it is preferably 30% by weight or less (for example, 15% by weight or less, Wt% or less). The black layer may contain white pigments such as titanium dioxide, zinc oxide, and white pigments, or other coloring agents, and may contain substantially no colorant other than the black coloring agent.

The thickness of the entire black layer is usually 0.1 μm or more, preferably 0.5 μm or more, more preferably 0.7 μm or more (eg, 0.8 μm or more, typically 1 μm or more) Is preferably 10 탆 or less, preferably 7 탆 or less, and more preferably 5 탆 or less (for example, 3 탆 or less, typically 2 탆 or less). In the black layer containing two or more sub-layers, the thickness of each sub-layer is usually preferably from 0.5 to 2 탆.

(Resin film layer)

In the pressure-sensitive adhesive sheet disclosed herein, a base material (support base material) supporting (adhering) the pressure-sensitive adhesive layer is typically formed of a resin film layer containing a resin material as a main component (for example, Is preferably contained. In this specification, the term &quot; resin film &quot; typically refers to a substantially non-foamed resin film. That is, the resin film in this specification may be one in which bubbles are substantially absent (voidless) in the resin film. Therefore, the resin film is a concept distinct from a so-called foam film. Further, the resin film is typically a substantially non-porous film, and is a concept distinguished from a so-called nonwoven fabric or woven fabric. A base material that does not contain a porous layer such as a foam, a nonwoven fabric, or a woven fabric, that is, a base made of a non-porous layer can be preferably used. The resin film generally tends to have a higher mechanical strength such as tensile strength than a foam, a nonwoven fabric, or a woven fabric. Further, the processability (for example, punching processability) is excellent. Therefore, a pressure-sensitive adhesive sheet using a substrate containing a resin film is advantageous from the viewpoint of workability, dimensional accuracy, and handleability. The substrate containing such a resin film can be preferably used as a substrate in the techniques disclosed herein from the viewpoints of dimensional stability, thickness accuracy, cost efficiency, and the like.

Suitable examples of the resin material constituting the resin film layer disclosed herein include a polyolefin resin and a polyester resin. Here, the polyolefin-based resin means a resin containing a polyolefin in a proportion exceeding 50% by weight. Likewise, a polyester resin means a resin containing a polyester in a proportion exceeding 50% by weight. Examples of the polyolefin-based resin film include a polyethylene (PE) -based resin, a polypropylene-based resin, an ethylene-propylene copolymer, and an ethylene-butene copolymer. Examples of the polyester resin include a polyethylene terephthalate (PET) resin, a polybutylene terephthalate (PBT) resin, a polyethylene naphthalate resin, and a polybutylene naphthalate resin. Among them, a polyester resin is preferable from the viewpoint of an embossability (in particular, an embossing property of the acrylic pressure-sensitive adhesive layer), and a PET resin is particularly preferable in terms of strength and workability.

The resin film layer may contain various additives such as a filler (inorganic filler, organic filler, etc.), an antioxidant, an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant and a plasticizer, if necessary. The blending ratio of various additives is usually about 30% by weight or less (for example, less than 20% by weight, typically 10% by weight or less).

 As the resin film layer, a transparent film (typically, a transparent resin film) can be preferably employed. Such a resin film layer may be substantially free of a coloring agent. Here, the resin film layer substantially containing no coloring agent means that the content of the coloring agent is less than 1% by weight, preferably less than 0.1% by weight. Alternatively, the resin film layer in the technique disclosed herein may be colored in black or white (e.g., milky white) or other colors in order to exhibit desired design characteristics or optical characteristics (e.g., light shielding property) . For example, organic or inorganic coloring agents (pigments, dyes, etc.) known in the material constituting the resin film layer may be blended. The resin film layer colored in black may be a black layer.

The resin film layer disclosed herein may have a single layer structure, or may have a multilayer structure of two layers, three layers or more. From the viewpoint of the shape stability, it is preferable that the resin film layer has a single-layer structure. The method of producing the resin film layer may be suitably employed in the conventionally known method and is not particularly limited. For example, conventionally known general film forming methods such as extrusion molding, inflation molding, T die cast molding, calender roll molding and the like can be suitably employed.

The surface of the resin film layer may be subjected to a conventionally known surface treatment such as corona discharge treatment, plasma treatment, ultraviolet ray irradiation treatment, acid treatment, alkali treatment, application of a primer (formation of a primer layer). Such a surface treatment may be a treatment for improving the adhesion between the resin film layer and the pressure-sensitive adhesive layer and the adhesion between the resin film layer and the black layer. Further, the technique disclosed herein is applicable to a case where a primer layer is not formed between a resin film layer and a pressure-sensitive adhesive layer and / or between a resin film layer and a black layer, and a resin film layer and a pressure- Can be preferably implemented in a direct contact form. The pressure sensitive adhesive sheet having such a configuration can be made thinner.

The thickness of the resin film layer is not particularly limited, and may be 30 占 퐉 or less, for example. By making the thickness of the resin film layer thin, the pressure-sensitive adhesive sheet also becomes thin, and furthermore, the product to which the pressure-sensitive adhesive sheet is applied can be made advantageous in terms of thinning, downsizing, lightening, and resource saving. Further, by making the resin film layer thinner, the heat radiation efficiency of the heat radiation sheet (typically, a graphite sheet) can be improved. The thickness of the resin film layer is preferably 12 占 퐉 or less, more preferably 9 占 퐉 or less (for example, 7 占 퐉 or less, typically 5 占 퐉 or less). In particular, when the thickness, weight, and the like are particularly emphasized, the thickness of the resin film layer is preferably 3 m or less (for example, 2 m or less). From the viewpoints of handleability and workability, it is preferable that the thickness of the resin film layer is approximately 0.5 占 퐉 or more (for example, 1 占 퐉 or more).

(Mat layer)

The substrate disclosed herein preferably contains a matte layer. Thereby, the gloss value can be preferably adjusted to a desired range. Here, the mat layer refers to a layer which reduces the gloss of the back surface of the pressure-sensitive adhesive sheet by forming the layer. Further, the degree of degradation or degree of gloss can be grasped by measuring the gloss value of 60 DEG described above. Since the surface of the mat layer can be the back surface of the pressure sensitive adhesive sheet, the 60 deg. Gloss value of the surface of the mat layer can take a value within the range shown as the 60 deg. Gloss value of the back surface of the pressure sensitive adhesive sheet.

The mat layer disclosed herein may typically be a layer constituting the back surface of the adhesive sheet. In that case, the mat layer can be arranged to cover the surface of the black layer in the adhesive sheet. It is preferable that the mat layer is formed on the outer surface of the black layer in order to combine the protective function of the black layer. Further, since the color feeling and designability on the back side of the adhesive sheet depend on the black layer, the mat layer is typically preferably transparent (including translucency). The mat layer may be a layer (a layer having a matte treated surface) subjected to surface treatment such as embossing or sand blasting on the surface thereof, or a matte layer having a light extinguishing property when formed on the surface of the black layer by application or the like do. The mat layer typically has a single layer structure, but may have a multi-layer structure.

The mat layer disclosed herein preferably has a light-emitting property depending on its composition. For example, the mat layer may be one containing a mat member. Thus, it is possible to impart light-extinguishing properties without performing additional surface treatment. The mat member is typically in a particulate form and is preferably transparent (typically colorless transparent). The shape of the particles of the mat member is not particularly limited and may be a spherical shape or the like.

The mat member may be either organic particles or inorganic particles, or both of them may be used. Examples of the organic particles include acrylic resin particles such as polymethylmethacrylate particles, polystyrene particles, styrene-acrylic resin particles, polycarbonate particles, urethane resin beads, epoxy resin beads, polyester resin beads , And polyester urethane resin beads. Examples of the inorganic particles include silicon dioxide (silica) particles, titanium dioxide particles, barium sulfate particles, calcium carbonate particles, mica, talc, and the like. These may be used singly or in combination of two or more. Among them, acrylic resin particles, urethane resin beads, and silica particles are preferable.

The average particle diameter of the mat member is not limited to a specific range because it is determined according to the required degree of extinction and the thickness of the mat layer, and is suitably about 0.1 mu m or more, preferably 0.5 mu m or more (for example, Typically &gt; 1 micron). The average particle diameter is suitably 20 m or less, preferably 8 m or less (for example, 3 m or less, typically 2 m or less). The average particle diameter of the mat member is preferably at least half of the thickness of the mat layer, and is preferably equal to or larger than the thickness of the mat layer, from the viewpoint of sufficiently exhibiting the dimming property. From the viewpoints of appearance and application workability, it is preferable that the average particle diameter of the mat member is set to about 10 times or less (for example, 5 times or less, typically 3 times or less) the thickness of the mat layer.

The content of the matting material is not limited to a specific range, as it is set in accordance with the degree of extinction required, the particle diameter of the matting material, and the like, but is preferably at least 0.5% by weight in the matte layer, For example, at least 2% by weight, typically at least 3% by weight). The content of the matting material in the matting layer is preferably about 40% by weight or less, more preferably about 20% by weight or less (for example, about 10% by weight or less, typically about 8% by weight or less).

The mat layer may contain other additive components such as a resin component and a dispersant. When the matte layer is transparent, the matte layer substantially contains no coloring agent. Here, the term "substantially not containing a coloring agent" means that the content of the coloring agent is less than 1% by weight, preferably less than 0.1% by weight.

Examples of the resin component contained in the mat layer include polyurethane resin, phenol resin, epoxy resin, urea melamine resin, silicone resin, phenoxy resin, methacrylic resin, acrylic resin, polyarylate resin, poly A styrene-acrylic resin, a styrene-maleic acid resin, a polyvinyl chloride, a vinyl chloride-vinyl acetate copolymer, an ethylene-vinyl acetate copolymer, a polyvinyl acetate, a polyvinylidene chloride , Polycarbonate, cellulose, polyacetal, and alkyd resin. The resin component may be used singly or in combination of two or more kinds. The resin composition for forming the mat layer (resin composition for forming a mat layer) may be a solvent-like composition, a thermosetting composition or an ultraviolet-curing composition, but from the viewpoint of layer formability and heat resistance, a thermosetting or ultraviolet setting type is preferable Do.

The method for forming the mat layer using the composition for forming a mat layer is not particularly limited, and various printing processing methods can be employed. The print processing method is not particularly limited, and various publicly known methods such as offset printing, silkscreen printing, iron plate printing, flexographic printing, and gravure printing can be suitably employed. Specifically, a solid component (typically, a resin component or a dispersant) constituting the composition is dissolved or dispersed in an appropriate solvent, and a suitable method among the above-mentioned print processing methods is employed to print the obtained composition on a black layer or a resin film layer By the treatment, the mat layer can be formed.

The thickness of the mat layer is suitably about 0.1 mu m or more, preferably about 0.2 mu m or more (for example, 0.3 mu m or more, typically 0.5 mu m or more) in consideration of imparting light-quenching property and coating workability. From the viewpoint of thinning, the thickness is suitably about 5 탆 or less, and preferably about 3 탆 or less (for example, 2 탆 or less, typically 1.5 탆 or less).

(Additional layer)

The substrate disclosed herein may have an additional layer in addition to the black layer, the resin film layer, and the mat layer. For example, the substrate may be provided on the surface of the matte layer, or in place of the matte layer, with an additional top coating layer such as a protective layer or a peeling treatment layer having chemical resistance. Such top coating layer can constitute the outermost surface (back surface of the pressure-sensitive adhesive sheet) of the substrate. From the viewpoint of thinning of the pressure-sensitive adhesive sheet, it is preferable that there is no undercoating layer between the resin film layer and the black layer yarn or between the black layer and the matte layer, but a subbing layer or the like may be formed in order to improve interlayer adhesion.

The thickness (total thickness) of the substrate is not particularly limited, and may be approximately 100 탆 or less. By thinning the thickness of the substrate, the pressure-sensitive adhesive sheet also becomes thin, and furthermore, the product to which the pressure-sensitive adhesive sheet is applied can be made thinner, smaller, lighter, and resource-saving. Further, by making the substrate thinner, the heat radiation efficiency of the heat-radiating sheet (typically, graphite sheet) can be improved. From the viewpoint of limiting the total thickness of the pressure-sensitive adhesive sheet to a predetermined value or less and obtaining a high adhesive performance or the like, the thickness of the substrate is preferably 40 占 퐉 or less, more preferably 30 占 퐉 or less, further preferably 20 占 퐉 or less Preferably 12 mu m or less, and particularly preferably 9 mu m or less (for example, 7 mu m or less, typically 5 mu m or less). From the viewpoints of handling property and processability, the thickness of the base material is usually about 2 mu m or more, preferably 3 mu m or more (for example, 3.5 mu m or more).

<Pressure-sensitive adhesive layer>

In the technique disclosed herein, the kind of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited. The pressure-sensitive adhesive may be at least one kind or two or more kinds of rubber-like polymers known in the pressure-sensitive adhesive art, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers and fluorine polymers As a base polymer. From the standpoint of adhesion performance and cost, a pressure-sensitive adhesive containing an acrylic polymer or a rubber-based polymer as a base polymer can be preferably employed. Among them, a pressure-sensitive adhesive (acrylic pressure-sensitive adhesive) comprising an acrylic polymer as a base polymer is preferable. Hereinafter, a pressure-sensitive adhesive sheet comprising an acrylic pressure-sensitive adhesive, that is, a pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer will be mainly described. However, the present invention is not intended to limit the pressure-sensitive adhesive layer of the pressure-

The "base polymer" of the pressure-sensitive adhesive refers to a main component of the rubber-like polymer contained in the pressure-sensitive adhesive. The rubber-like polymer is a polymer which exhibits rubber elasticity in a temperature region near room temperature. In this specification, the term &quot; main component &quot; refers to a component that contains more than 50% by weight, unless otherwise specified.

The "acrylic polymer" refers to a polymer containing monomer units derived from a monomer having at least one (meth) acryloyl group in one molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least one (meth) acryloyl group in one molecule is also referred to as an &quot; acrylic monomer &quot;. Thus, the acrylic polymer in this specification is defined as a polymer containing monomer units derived from acrylic monomers. As a typical example of the acrylic polymer, an acrylic polymer among the total monomer components used in the synthesis of the acrylic polymer is more than 50% by weight of the acrylic monomer.

The term &quot; (meth) acryloyl &quot; means a generic term for acryloyl and methacryloyl. Likewise, "(meth) acrylate" means acrylate and methacrylate, and "(meth) acryl" means acryl and methacryl, respectively.

As the acrylic polymer, for example, a polymer of a monomer raw material which contains an alkyl (meth) acrylate as a main monomer and can further contain a monomer having a copolymerization with the main monomer is preferable. Herein, the main monomer means a component which accounts for more than 50% by weight of the monomer composition in the monomer raw material.

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be suitably used.

CH ₂ = C (R ¹ ) COOR ² (1)

Here, R ¹ in the formula (1) is a hydrogen atom or a methyl group. R ² is a straight chain alkyl group having 1 to 20 carbon atoms. Hereinafter, the range of the number of carbon atoms may be represented as &quot; C _{1-20 &} quot ;. To the storage modulus of the pressure-sensitive adhesive from the viewpoint of, R ² is C _1-14 alkyl (meth) chain alkyl group (e.g., C _2-10, typically a C _{4- 8)} acrylate as a main monomer It is suitable. In view of adhesive properties, R ¹ is a hydrogen atom, R ² a is preferably an alkyl acrylate (hereinafter also referred to as simply _4- C ₈ alkyl acrylate) chain alkyl group of _4-8 C as a main monomer.

Examples of the alkyl (meth) acrylate in which R ² is a C _1-20 linear alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (Meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isooctyl (meth) acrylate, (Meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, , Hexadecyl (meth) acrylate, Other decyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate. These alkyl (meth) acrylates may be used singly or in combination of two or more. Preferred alkyl (meth) acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).

The ratio of the alkyl (meth) acrylate to the entire monomer component used in the synthesis of the acrylic polymer is preferably 70% by weight or more, more preferably 85% by weight or more, and still more preferably 90% by weight or more. The upper limit of the alkyl (meth) acrylate ratio is not particularly limited, but usually it is preferably 99.5% by weight or less (for example, 99% by weight or less). Alternatively, the acrylic polymer may be substantially polymerized only with alkyl (meth) acrylate. In addition, when using the C _{4- 8} alkyl acrylate as a monomer component, the ratio of the _4- C ₈ alkyl acrylate of alkyl (meth) acrylate contained in the monomer component, and not less than 70% by weight, 90 parts by weight , And still more preferably 95 wt% or more (typically 99 to 100 wt%). The techniques disclosed herein can preferably be implemented in the form of at least 50 wt% (e.g., at least 60 wt%, and typically at least 70 wt%) of the total monomer components being BA. In a preferred form, the total monomer component may contain 2 EHA in a lesser proportion than BA.

The acrylic polymer in the techniques disclosed herein may be copolymerized with other monomers (other monomers) within the range not significantly impairing the effect of the present invention. The other monomer can be used, for example, for the purpose of adjusting the glass transition temperature (Tg) of the acrylic polymer and adjusting the adhesion performance (for example, peelability). For example, examples of the monomer capable of improving the cohesive force and heat resistance of the pressure-sensitive adhesive include sulfonic acid group-containing monomers, phosphoric acid group-containing monomers, cyano group-containing monomers, vinyl esters and aromatic vinyl compounds. Suitable examples of these include vinyl esters. Specific examples of the vinyl esters include vinyl acetate (VAc), vinyl propionate, and vinyl laurate. Of these, VAc is preferable.

As other monomers capable of introducing a functional group capable of becoming a crosslinking point to the acrylic polymer or contributing to improvement of the adhesive strength, a monomer containing a hydroxyl group (OH group), a monomer containing a carboxyl group, an monomer containing an acid anhydride group, , An amino group-containing monomer, an imide group-containing monomer, an epoxy group-containing monomer, (meth) acryloylmorpholine, vinyl ethers and the like.

One suitable example of the acrylic polymer in the techniques disclosed herein is an acrylic polymer in which a carboxyl group-containing monomer is copolymerized as the other monomer. Examples of the carboxyl group-containing monomer include acrylic acid (AA), methacrylic acid (MAA), carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, do. Among them, AA and MAA are preferable.

Another suitable example is an acrylic polymer in which a hydroxyl group-containing monomer is copolymerized as the other monomer. Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl Hydroxyalkyl (meth) acrylates such as 4-hydroxybutyl (meth) acrylate; Polypropylene glycol mono (meth) acrylate; N-hydroxyethyl (meth) acrylamide, and the like. Among them, preferable examples of the hydroxyl group-containing monomer include a hydroxyalkyl (meth) acrylate in which the alkyl group is a linear chain having 2 to 4 carbon atoms.

These "other monomers" may be used singly or in combination of two or more. The total content of the other monomers is preferably less than or equal to about 40 wt% (typically, 0.001 to 40 wt%), more preferably less than or equal to about 30 wt% (typically between 0.01 and 30 wt% , 0.1 to 10% by weight).

When the carboxyl group-containing monomer is used as the other monomer, the content thereof is suitably at least about 0.1% by weight (for example, at least 0.2% by weight, typically at least 0.5% by weight) of the entire monomer component, (For example, 8% by weight or less, typically 5% by weight or less). When the hydroxyl group-containing monomer is used as the other monomer, the content thereof is suitably about 0.001% by weight or more (for example, 0.01% by weight or more, typically 0.02% by weight or more) (For example, 5% by weight or less, typically 2% by weight or less).

It is appropriate that the copolymer composition of the acrylic polymer is designed such that the glass transition temperature (Tg) of the polymer is -15 캜 or lower (typically -70 캜 or higher and -15 캜 or lower). The Tg of the acrylic polymer is preferably -25 캜 or lower (for example, -60 캜 or higher and -25 캜 or lower), more preferably -40 캜 or lower (for example, -60 캜 or higher and -40 캜 or lower) . It is preferable to set the Tg of the acrylic polymer to the above-mentioned upper limit value or less from the viewpoints of workability of adhesion of the pressure-sensitive adhesive sheet and the like.

The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the kind or amount of the monomer used for synthesis of the polymer). Here, the Tg of the acrylic polymer refers to the Tg obtained by Fox's equation based on the composition of the monomer component used in the synthesis of the polymer. The formula of Fox is a relational expression of the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer of each of the monomers constituting the copolymer as described below.

1 / Tg =? (Wi / Tgi)

Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio by weight), Tgi is the glass transition temperature of the homopolymer of monomer i And the transition temperature (unit: K).

As the glass transition temperature of the homopolymer used for the calculation of Tg, the values described in the known data shall be used. For example, for the monomers exemplified below, the following values are used as the glass transition temperature of the homopolymer of the monomer.

2-ethylhexyl acrylate -70 ° C

n-butyl acrylate -55 ° C

Ethyl acrylate -22 ° C

Methyl acrylate 8 ℃

Methyl methacrylate 105 ℃

2-hydroxyethyl acrylate -15 ℃

4-hydroxybutyl acrylate -40 ° C

Vinyl acetate 32 ℃

Styrene 100 ℃

Acrylic acid 106 ° C

Methacrylic acid 228 ° C

The values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) will be used as the glass transition temperature of the homopolymer other than those exemplified above. The highest value is adopted for monomers in which plural kinds of values are described in this document.

When the glass transition temperature of the homopolymer is not described in the above document, a value obtained by the following measuring method is used.

Specifically, 100 parts by weight of a monomer, 0.2 part by weight of 2,2'-azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were charged into a reactor equipped with a thermometer, a stirrer, a nitrogen inlet tube and a reflux condenser tube And stirred for 1 hour while flowing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, the temperature was raised to 63 캜 and the reaction was carried out for 10 hours. Subsequently, the solution was cooled to room temperature to obtain a homopolymer solution having a solid concentration of 33% by weight. Subsequently, this homopolymer solution is applied on a release liner in a pourable manner and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. This test sample was punched into a disc shape having a diameter of 7.9 mm and sandwiched between parallel plates and subjected to a shear strain at a frequency of 1 Hz using a viscoelasticity tester (model name "ARES" manufactured by T.A. Instrument, Japan) The viscoelasticity is measured by the shear mode at a temperature raising rate of -70 DEG C to 150 DEG C and 5 DEG C / min in the temperature region, and the temperature (the temperature at which the G "curve becomes the maximum) corresponding to the peak top temperature of the shear loss elastic modulus G" Tg of the homopolymer.

The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as methods for synthesizing an acrylic polymer such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization and photopolymerization can be suitably employed. For example, a solution polymerization method can be preferably used. As a method of supplying a monomer at the time of solution polymerization, a batch feeding method, a continuous feeding (dropping) method, a divided feeding (dropping) method and the like in which the entire monomer raw materials are fed at once can be suitably employed. The polymerization temperature may be appropriately selected according to the type of the monomer and solvent to be used and the kind of the polymerization initiator to be used and may be, for example, about 20 ° C or higher (typically 40 ° C or higher) Typically below 140 ° C). In a preferred form, a polymerization temperature of about 75 占 폚 or lower (more preferably about 65 占 폚 or lower, for example, about 45 占 폚 to 65 占 폚) may be employed.

The solvent (polymerization solvent) to be used for solution polymerization may be appropriately selected from conventionally known organic solvents. For example, aromatic compounds such as toluene (typically aromatic hydrocarbons); Acetic acid esters such as ethyl acetate; Aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; Halogenated alkanes such as 1,2-dichloroethane and 1,2-dichloroethane; Lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; Ketones such as methyl ethyl ketone; , Or a mixed solvent of two or more of them may be used.

The initiator used in the polymerization may be appropriately selected from conventionally known polymerization initiators depending on the kind of the polymerization method. For example, one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used. Other examples of the polymerization initiator include persulfates such as potassium persulfate; Peroxide initiators such as benzoyl peroxide and hydrogen peroxide; Substituted ethane-based initiators such as phenyl-substituted ethane; Aromatic carbonyl compounds; And the like. As another example of the polymerization initiator, there may be mentioned a redox type initiator by a combination of a peroxide and a reducing agent. These polymerization initiators may be used singly or in combination of two or more. The amount of the polymerization initiator to be used may be an ordinary amount, and may be selected within a range of, for example, about 0.005 to 1 part by weight (typically 0.01 to 1 part by weight) based on 100 parts by weight of the total monomer component.

According to the solution polymerization, a polymerization reaction solution in which the acrylic polymer is dissolved in an organic solvent is obtained. The pressure-sensitive adhesive layer in the techniques disclosed herein may be formed of a pressure-sensitive adhesive composition containing the polymerization reaction solution or an acrylic polymer solution obtained by subjecting the reaction solution to an appropriate post-treatment. As the acrylic polymer solution, a solution prepared by appropriately adjusting the viscosity of the polymerization reaction solution may be used. Alternatively, an acrylic polymer solution prepared by synthesizing an acrylic polymer by a polymerization method other than solution polymerization (for example, emulsion polymerization, photopolymerization, bulk polymerization, etc.) and dissolving the acrylic polymer in an organic solvent may be used.

The weight average molecular weight (Mw) of the base polymer (preferably an acrylic polymer) in the techniques disclosed herein is not particularly limited, and may be, for example, in the range of 10 10 ⁴ to 500 10 ⁴ . The Mw of the base polymer is preferably in the range of 10 x 10 ⁴ or more (for example, 20 x 10 ⁴ or more, typically 35 x 10 ⁴ or more), and more preferably 150 x 10 ⁴ (For example, not more than 75 × 10 ⁴ , typically not more than 65 × 10 ⁴ ). Here, Mw refers to a value in terms of standard polystyrene obtained by GPC (gel permeation chromatography). As the GPC apparatus, for example, a model name &quot; HLC-8320GPC &quot; (column: TSKgelGMH-H (S), manufactured by TOSOH CORPORATION) may be used.

The pressure-sensitive adhesive in the technique disclosed herein may be a composition containing a tackifying resin. Examples of the tackifier resin include, but are not limited to, a rosin-based tackifier resin, a terpene-based tackifier resin, a hydrocarbon-based tackifier resin, an epoxy-based tackifier resin, a polyamide tackifier resin, Phenol-based tackifying resins, and ketone-based tackifying resins. These tackifying resins may be used singly or in combination of two or more. When an acrylic polymer is used as the base polymer, it is preferable to use a rosin-based tackifying resin.

Examples of the rosin-based tackifying resin include unmodified rosin (raw rosin) such as gum rosin, wood rosin and tall oil rosin; Modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosin, etc.) modified by hydrogenation, disproportionation, polymerization or the like of these unmodified rosins; And various other rosin derivatives. Examples of the rosin derivatives include rosin esters such as rosin esters obtained by esterification of unmodified rosin with alcohols (that is, esters of rosin), and esters of modified rosin with alcohols (i.e., esters of modified rosins) Ryu; Unsaturated fatty acid modified rosin modified with unmodified rosin or modified rosin with unsaturated fatty acid; Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; Rosin alcohols obtained by reducing a carboxyl group in unmodified rosin, modified rosin, unsaturated fatty acid-modified rosin or unsaturated fatty acid-modified rosin ester; Metal salts of rosins (especially rosin esters) such as unmodified rosin, modified rosin, and various rosin derivatives; Rosin phenol resins obtained by adding phenol to an acid catalyst to rosin (unmodified rosin, modified rosin, various rosin derivatives, etc.) and thermally polymerizing them.

The softening point (softening temperature) of the tackifier resin to be used is not particularly limited. For example, those having a softening point of about 100 DEG C or higher (preferably about 120 DEG C or higher) can be preferably used. A rosin-based tackifying resin having such a softening point (for example, an esterified product of polymerized rosin) can be preferably used. The upper limit of the softening point of the tackifier resin is not particularly limited and may be about 200 占 폚 or lower (typically about 180 占 폚 or lower, for example, about 150 占 폚 or lower). The softening point of the tackifier resin is defined as a value measured by a softening point test method (rolling method) specified in either JIS K 5902 or JIS K 2207.

The amount of the tackifier resin to be used is not particularly limited and can be suitably set in accordance with the intended adhesive performance (peel strength, etc.). For example, it is preferable to use the tackifier resin in a proportion of about 10 parts by weight or more (more preferably 15 parts by weight or more, and still more preferably 20 parts by weight or more) with respect to 100 parts by weight of the base polymer, Preferably 100 parts by weight or less (more preferably 80 parts by weight or less, and still more preferably 60 parts by weight or less).

In the technique disclosed herein, the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer may contain a crosslinking agent, if necessary. The kind of the crosslinking agent is not particularly limited and can be appropriately selected from conventional crosslinking agents. Examples of such crosslinking agents include crosslinking agents such as isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, melamine crosslinking agents, peroxide crosslinking agents, urea crosslinking agents, metal alkoxide crosslinking agents, metal chelating crosslinking agents, metal salt crosslinking agents, Carbodiimide-based crosslinking agents, and amine-based crosslinking agents. The crosslinking agent may be used alone or in combination of two or more. Among them, from the viewpoint of improving the cohesive force, the use of an isocyanate-based cross-linking agent and / or an epoxy-based cross-linking agent is preferred, and the use of an isocyanate-based cross-linking agent is particularly preferable. The amount of the crosslinking agent to be used is not particularly limited. For example, about 10 parts by weight or less, preferably about 0.005 to 10 parts by weight, and more preferably about 0.01 to 5 parts by weight, based on 100 parts by weight of the base polymer (preferably an acrylic polymer) You can choose.

The pressure-sensitive adhesive layer in the technique disclosed herein may be colored to exhibit desired design characteristics or optical properties (e.g., light shielding property). One or two or more kinds of known organic or inorganic coloring agents (pigments, dyes, etc.) may be suitably used in the coloring. For example, by containing a black coloring agent such as carbon black in the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer can be colored in black. The content of the colorant is not particularly limited and may be less than 15 parts by weight based on 100 parts by weight of the base polymer, for example. It is preferable that the content of the colorant is less than 10 parts by weight (for example, less than 5 parts by weight, typically less than 3 parts by weight) based on 100 parts by weight of the base polymer from the viewpoint of suppressing deterioration of the adhesive property. The technique disclosed here can be preferably implemented in a form in which the pressure-sensitive adhesive layer is substantially free from inorganic and organic coloring agents, from the viewpoint of adhesion performance. For example, the content of the colorant may be preferably 0 to 1 part by weight based on 100 parts by weight of the base polymer.

The pressure-sensitive adhesive composition may contain various additives commonly used in the pressure-sensitive adhesive composition field, such as a leveling agent, a crosslinking aid, a plasticizer, a softener, an antistatic agent, an antioxidant, an ultraviolet absorber, an antioxidant and a light stabilizer. Such various additives can be used by conventionally known methods, and the present invention is not particularly described, and thus a detailed description thereof will be omitted.

The pressure-sensitive adhesive layer (pressure-sensitive adhesive layer) disclosed herein may be a pressure-sensitive adhesive layer formed of various types of pressure-sensitive adhesive compositions such as an aqueous pressure-sensitive adhesive composition, a solvent-type pressure-sensitive adhesive composition, a hot melt pressure- The water-based pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive (pressure-sensitive adhesive layer-forming component) in a solvent (water-based solvent) containing water as a main component. Typically, One type of composition), and the like. The solvent-type pressure-sensitive adhesive composition means a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive in an organic solvent. The technique disclosed here can preferably be implemented in the form of a pressure-sensitive adhesive layer formed of a solvent-type pressure-sensitive adhesive composition, from the viewpoint of adhesion properties and the like.

The pressure-sensitive adhesive layer disclosed herein can be formed by a conventionally known method. For example, a method (direct method) of forming a pressure-sensitive adhesive layer by directly applying (typically applying) a pressure-sensitive adhesive composition to a substrate and drying it as described above can be employed. Further, a method (transfer method) in which a pressure-sensitive adhesive composition is applied to a surface (release surface) having releasability and then dried to form a pressure-sensitive adhesive layer on the surface and the pressure-sensitive adhesive layer is transferred to a substrate. From the viewpoint of productivity, the transfer method is preferable. As the peeling surface, the surface of the peeling liner, the back surface of the peeling treated substrate, or the like can be used. The pressure-sensitive adhesive layer disclosed herein is typically formed continuously, but the pressure-sensitive adhesive layer is not limited to such a shape. For example, it may be a pressure-sensitive adhesive layer formed in a regular or random pattern such as a point shape or a stripe shape.

The application of the pressure-sensitive adhesive composition can be carried out using conventionally known coaters such as a gravure roll coater, a die coater, a bar coater and the like. Alternatively, the pressure-sensitive adhesive composition may be applied by impregnation or curtain coating.

From the standpoint of promoting the crosslinking reaction and improving the production efficiency, the drying of the pressure-sensitive adhesive composition is preferably carried out under heating. The drying temperature may be, for example, about 40 to 150 DEG C, and preferably about 60 to 130 DEG C. Aging may be carried out after drying the pressure-sensitive adhesive composition for the purpose of adjusting the component transfer in the pressure-sensitive adhesive layer, progressing the crosslinking reaction, and alleviating the distortion that may be present in the substrate or the pressure-sensitive adhesive layer.

The thickness of the pressure-sensitive adhesive layer disclosed herein is not particularly limited and may be appropriately selected depending on the purpose. (For example, 2 mu m or more, typically 4 mu m or more) is preferable in view of productivity such as drying efficiency and adhesion performance, and it is suitably about 200 mu m or less (for example, 140 mu m Or less, typically 80 μm or less) is suitable. From the viewpoint of restricting the total thickness of the pressure-sensitive adhesive sheet, the thickness is preferably from about 1 탆 to 40 탆, more preferably from 1.2 탆 to 30 탆 (for example, 20 탆 or less, typically 10 탆 or less )to be. Even when the thickness of the pressure-sensitive adhesive layer is 5 占 퐉 or less (or 3 占 퐉 or less), the technique disclosed herein can be carried out. The thin pressure-sensitive adhesive layer is advantageous in terms of thinning of the pressure-sensitive adhesive sheet, downsizing, light weight, resource saving, and the like. Further, from the viewpoint of heat radiation efficiency by the graphite sheet, the pressure-sensitive adhesive layer is preferably thin.

<Peel Liner>

In the technique disclosed herein, a release liner can be used for forming a pressure-sensitive adhesive layer, for producing a pressure-sensitive adhesive sheet, for preserving, distributing, and shaping the pressure-sensitive adhesive sheet before use. The release liner is not particularly limited, and examples thereof include a release liner having a release treatment layer on the surface of a liner base such as a resin film or paper, a release liner such as a fluorine-based polymer (polytetrafluoroethylene), a polyolefin- Propylene and the like), and the like can be used. The peeling treatment layer may be formed by surface-treating the liner base with a peeling agent such as silicone, long chain alkyl, fluorine, or molybdenum sulfide. The release liner used for the pressure sensitive adhesive sheet of one side adhesive typically has a surface which comes into contact with the adhesive surface of the pressure sensitive adhesive sheet as a releasable surface (exfoliated surface), and the other surface may be exfoliated. The thickness (total thickness) of the release liner is not particularly limited, but is preferably set to about 10 탆 or more (for example, 15 탆 or more) from the viewpoint of peeling workability, handleability, Or less, for example, 100 mu m or less).

<Applications>

The pressure-sensitive adhesive sheet disclosed herein is used by attaching to a graphite sheet. BACKGROUND ART [0002] Graphite sheets are heat-radiating sheets for dissipating heat from heat generating elements (batteries, IC chips, etc.) and are preferably used in various small electronic apparatuses. For example, the graphite sheet is disposed at a position adjacent to a power generating element such as a battery or an IC chip in the electronic device, or around the power generating element. Such a graphite sheet has external appearance irregularity, and a thin sheet is likely to be broken. Therefore, a pressure-sensitive adhesive sheet is adhered to the surface of the graphite sheet for the purpose of improvement in appearance and protection. By applying the pressure-sensitive adhesive sheet disclosed herein to the graphite sheet, an improvement in appearance quality is preferably realized. In addition, a sheet having a predetermined color (low degree of brightness, chromaticity) and a gloss value on the back surface of the pressure sensitive adhesive sheet can exhibit a black color with a high degree of suppression of glossiness and thus can be well harmonized with the color of the graphite sheet and its peripheral members . Further, according to the pressure-sensitive adhesive sheet having a light transmittance in a predetermined range, the color tone of the graphite sheet can be appropriately reflected on the outer surface to give a desired color, texture, and design. Although not particularly limited, the pressure-sensitive adhesive sheet disclosed herein is preferably applied to a graphite sheet having a thickness of 4 to 100 탆 and / or an arithmetic mean surface roughness Ra of 0.005 to 5 탆.

The pressure-sensitive adhesive sheet disclosed herein can be preferably applied to portable electronic device applications. For example, a mobile phone, a smart phone, a tablet personal computer, a notebook computer, various wearable devices (for example, a wrist watch such as a wrist watch, An eyewear type including an eye type (including a monocular type, a binocular type, and a head mount type), a clothing type to be attached in the form of an accessory to a shirt, a sock, a hat, Etc.), digital cameras, digital video cameras, sound devices (Walkman, IC recorders, etc.), calculators (electronic calculators and the like), portable game devices, electronic dictionaries, electronic notebooks, electronic books, And can be preferably used for the purpose of protecting members and imparting designs in a portable electronic device such as a TV, a portable printer, a portable scanner, and a mobile modem. In this specification, &quot; portable &quot; means not only being portable, but also having a level of portability that allows an individual (a standard adult) to carry it relatively easily.

The matters disclosed by this specification include the following.

(1) A single-sided adhesive pressure-sensitive adhesive sheet used for attaching to a graphite sheet,

And a pressure-sensitive adhesive layer formed on one surface of the base material,

The substrate contains a black layer,

The 60 deg. Gloss value of the back surface of the pressure-sensitive adhesive sheet is 10 or less,

Wherein the adhesive sheet has a light transmittance of 12 to 30%.

(2) The above-described substrate comprises a resin film layer and a black layer,

The pressure-sensitive adhesive sheet according to the above (1), wherein the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive layer, the resin film layer and the black layer are laminated in this order.

(3) The pressure-sensitive adhesive sheet according to (2), wherein the thickness of the black layer is 2 m or less.

(4) The pressure-sensitive adhesive sheet according to (2) or (3), wherein the back surface of the pressure-sensitive adhesive sheet has a lightness L ^* defined by the L ^* a ^* b ^*

(5) The above-described substrate further comprises a mat layer,

The adhesive sheet according to any one of (2) to (4) above, wherein the substrate has a laminated structure in which the resin film layer, the black layer and the mat layer are laminated in this order.

(6) The pressure-sensitive adhesive sheet according to (5), wherein the mat layer contains a particulate mat member.

(7) The pressure-sensitive adhesive sheet according to (5) or (6), wherein the thickness of the mat layer is 2 占 퐉 or less.

(8) The pressure-sensitive adhesive sheet according to any one of (1) to (7), wherein the total thickness of the pressure-sensitive adhesive sheet is 30 占 퐉 or less.

(9) A pressure-sensitive adhesive sheet with a release liner, comprising the pressure-sensitive adhesive sheet according to any one of (1) to (8) and a release liner for protecting the adhesive surface of the pressure-sensitive adhesive sheet.

(10) The adhesive sheet according to any one of (1) to (8), which is disposed in a portable electronic device.

(11) The pressure-sensitive adhesive layer contains an acrylic polymer in a proportion exceeding 50% by weight of the polymer component contained in the pressure-sensitive adhesive layer,

The acrylic polymer includes, as a monomer component, a compound represented by the formula (1):

CH ₂ = C (R ¹ ) COOR ² (1)

(Meth) acrylate represented by the following formula (1), wherein R ¹ is a hydrogen atom or a methyl group, and R ² is a straight chain alkyl group having 1 to 20 carbon atoms, The pressure-sensitive adhesive sheet according to any one of (1) to (10) above.

(12) The alkyl (meth) acrylate may be at least one selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) (Meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, pentyl (meth) acrylate, (Meth) acrylate, octyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (Meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, Decyl (meth) acrylate, octa Chamber (meth) acrylate, nona-sensitive adhesive sheet according to decyl (meth) acrylate and eicosyl (meth) at least one member, the above-mentioned (11) is selected from the group consisting of acrylate.

(13) The pressure-sensitive adhesive sheet according to (11) or (12), wherein the alkyl (meth) acrylate is n-butyl acrylate and 2-ethylhexyl acrylate.

(14) The composition according to the above (14), wherein the alkyl (meth) acrylate is n-butyl acrylate and 2-ethylhexyl acrylate, and the 2-ethylhexyl acrylate is contained in the monomer component at a rate lower than n-butyl acrylate. The pressure-sensitive adhesive sheet according to any one of (11) to (13) above.

(15) The acrylic polymer further contains a functional group-containing monomer as the monomer component,

The functional group-containing monomer is at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, The pressure-sensitive adhesive sheet according to any one of (11) to (14), wherein the pressure-sensitive adhesive sheet is at least one selected from the group consisting of (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

(16) The pressure-sensitive adhesive layer as described in any one of (1) to (10), wherein the pressure-sensitive adhesive layer contains a rosin-based tackifier resin having a softening point of 100 ° C or more and 180 ° C or less,

The pressure-sensitive adhesive sheet according to any one of (1) to (15), wherein the content of the tackifier resin is 20 to 60 parts by weight based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer.

(17) The adhesive sheet according to any one of (1) to (16) above, wherein the substrate contains a polyethylene terephthalate-based resin film layer.

(18) The pressure-sensitive adhesive sheet according to any one of (1) to (17), wherein the black layer contains carbon black as a black pigment.

(19) The pressure-sensitive adhesive sheet according to any one of (1) to (18), wherein the thickness of the substrate is 9 占 퐉 or less.

(20) A single-sided adhesive pressure-sensitive adhesive sheet used for attaching to a graphite sheet disposed in a portable electronic device,

And a pressure-sensitive adhesive layer formed on one surface of the base material,

The substrate has a laminated structure in which a resin film layer, a black layer and a mat layer are laminated in this order,

The 60 deg. Gloss value of the back surface of the pressure-sensitive adhesive sheet is 10 or less,

The adhesive sheet has a light transmittance of 12 to 30%

The back surface of the pressure-sensitive adhesive sheet has a lightness L ^* defined by the L ^* a ^* b ^* colorimetric system of 40 or less,

The thickness of the black layer is 2 탆 or less,

The mat layer contains a particulate mat member,

The thickness of the mat layer is 2 탆 or less,

The total thickness of the pressure-sensitive adhesive sheet is 30 占 퐉 or less,

Wherein the pressure-sensitive adhesive layer contains an acrylic polymer in a proportion exceeding 50% by weight of the polymer component contained in the pressure-sensitive adhesive layer,

The acrylic polymer contains, as a monomer component, an alkyl (meth) acrylate in a proportion of 70% by weight or more,

Wherein the alkyl (meth) acrylate is n-butyl acrylate and 2-ethylhexyl acrylate, the 2-ethylhexyl acrylate is contained in the monomer component in a smaller proportion than n-butyl acrylate,

The acrylic polymer may further contain a functional group-containing monomer as the monomer component,

The functional group-containing monomer is at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (Meth) acrylate, and 4-hydroxybutyl (meth) acrylate, and is at least one member selected from the group consisting of

Wherein the pressure-sensitive adhesive layer contains a rosin-based tackifier resin having a softening point of 100 占 폚 or more and 180 占 폚 or less as a tackifier resin,

The content of the tackifier resin is 20 to 60 parts by weight based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer,

Wherein the resin film layer is a polyethylene terephthalate resin film layer,

The black layer contains carbon black as a black pigment,

Wherein the thickness of the substrate is 9 占 퐉 or less.

[Example]

Hereinafter, some embodiments according to the present invention will be described, but the present invention is not intended to be limited to what is shown in these embodiments. In the following description, &quot; part &quot; and &quot;% &quot; are by weight unless otherwise specified.

<Example 1>

A reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas introducing tube, a reflux condenser, and a dropping funnel was charged with 70 parts of BA as a monomer component, 27 parts of 2EHA, 3 parts of AA and 0.05 part of 4-hydroxybutyl acrylate, And 135 parts of toluene were charged and stirred for 2 hours while introducing nitrogen gas. After the oxygen in the polymerization system was removed in this manner, 0.1 part of AIBN as a polymerization initiator was added and the solution was polymerized at 60 DEG C for 6 hours to obtain a toluene solution of an acrylic polymer. The Mw of the acrylic polymer was about 40 × 10 ⁴ .

To 100 parts of the acrylic polymer contained in the toluene solution, 30 parts of polymerized rosin ester (trade name "PENCEL D-125", softening point 120 to 130 ° C, manufactured by Arakawa Chemical Industries, Ltd.) as an adhesion-imparting resin and 30 parts of an isocyanate- "Coronate L", manufactured by Toso Co., Ltd., solids content: 75%) was added to prepare an acrylic pressure-sensitive adhesive composition.

As a release liner, a polyester release film (trade name &quot; Diepoil MRF &quot;, thickness 38 mu m, manufactured by Mitsubishi Polyester Co., Ltd.) having a release face and a release face was prepared. The pressure-sensitive adhesive composition was coated on the release face of the release liner so that the thickness after drying became 2 占 퐉 and dried at 100 占 폚 for 2 minutes. In this way, a pressure-sensitive adhesive layer was formed on the peeling surface of the release liner.

Subsequently, a black printing layer having a thickness of about 1 占 퐉 was formed on one side (second surface) of a transparent PET film having a thickness of 2 占 퐉 (trade name "Mylar", manufactured by Dejinde DuPont Films) A black print layer-forming PET film (mat layer forming base) having a matte layer of about 1 탆 was prepared. The mat layer is formed by adding a matting material to a resin material and applying the mixed composition for forming a matte layer to the surface of the black printing layer. The black printing layer and the matting layer are all made of materials manufactured by Dainichiseika Kogyo Co.,

A pressure-sensitive adhesive layer formed on the release liner was bonded to the PET film side surface (first surface of the PET film layer) of the mat layer-forming base material to prepare the pressure-sensitive adhesive sheet of this example (transfer method). The release liner remained on the pressure-sensitive adhesive layer, and was used for protecting the surface (adhesive surface) of the pressure-sensitive adhesive layer.

<Example 2>

The composition of the black print layer (the change of the resin species, the amount of the black pigment to be used, etc.) and the composition of the mat layer (specifically, the amount of the mat member to be used) were changed so that the gloss and color of the back surface of the adhesive sheet were changed. Similarly, a pressure-sensitive adhesive sheet according to this example was produced.

<Example 3>

A pressure-sensitive adhesive sheet according to this example was produced basically in the same manner as in Example 2 except that a mat layer was not formed.

<Example 4>

A composition similar to the composition for forming a mat layer used in Example 2 was prepared except that the mat material was not contained. Using this mat material-free composition, a non-matte layer (top) was formed on the surface of the black print layer of the black print layer- Coating layer). The pressure-sensitive adhesive sheet of this example was produced in the same manner as in Example 2 except for this.

[evaluation]

The gloss values of the back surface, the brightness L ^* , the chromaticity a ^* and the chromaticity b ^* , the light transmittance (%) and the 180 degree peel strength (N / 20 mm) of the back surface were measured. The results are shown in Table 1.

[Defect Detectability]

The pressure-sensitive adhesive sheet of each example prepared above was attached to a commercially available graphite sheet (trade name &quot; Graffiti 25 mu m &quot;, manufactured by Kaneka Corporation, thickness 25 mu m) -SL-A48LCG &quot;, product of Dentsu Co., Ltd.). Then, the naked eye inspection of the graphite sheet was carried out over the pressure-sensitive adhesive sheet, and the ease of detection of defects (specifically, pin holes, etc.) was evaluated based on the following two criteria.

&Amp; cir &amp;: The defect detection operation could be efficiently performed

X: Defects were difficult to detect.

The results are shown in Table 1.

[Exterior]

The pressure-sensitive adhesive sheet of each example prepared above was attached to a commercially available graphite sheet (trade name &quot; Graffiti 25 m &quot;, manufactured by Kaneka Corporation, thickness 25 m) Respectively. In all the examples, no appearance defects were found, and since they had generally good appearance, evaluation was carried out in three steps of 1 to 3 to cover the superiority. The one having the best appearance was called three points, the one having the best appearance was rated as two points, and the one having the worst appearance was rated as one point. The results are shown in Table 1.

As shown in Table 1, in the pressure-sensitive adhesive sheet having the substrate containing the black layer, Example 1 in which the gloss value at 60 ° of the back surface of the pressure-sensitive adhesive sheet was not more than 10 and the light transmittance was 12 to 30% Or excellent in detectability of defects as compared with other examples in which the light transmittance is not satisfied. This result is considered to be attributable to the fact that the light transmittance was high and the influence of reflection of the room light was suppressed in addition to the improvement of the detection property beyond the adhesive sheet. In addition, the pressure-sensitive adhesive sheet of Example 1 obtained the best evaluation in appearance evaluation. This is considered to be due to the coloring of the black layer, the state in which the graphite sheet is shimmed over the pressure-sensitive adhesive sheet, and furthermore, the effect due to the deepening due to the low-glossiness of the back surface.

From the above results, it can be seen that the pressure-sensitive adhesive sheet having a 60 ° gloss value of 10 or less on the back side and a light transmittance of 12 to 30% and containing a black layer as a substrate has excellent appearance, It can be seen that a pressure-sensitive adhesive sheet for a graphite sheet is realized.

Although specific embodiments of the present invention have been described in detail, they are merely illustrative and do not limit the scope of the claims. The techniques described in the claims include various modifications and variations of the illustrated embodiments.

1 adhesive sheet
1A adhesive face
1B back face
10 substrate
10A One surface of the substrate (the pressure-sensitive adhesive layer side surface)
10B The other surface (rear surface)
12 resin film layer
The first surface of the 12A resin film layer
The second surface of the 12B resin film layer
14 black layer
16 mat layer
20 pressure-sensitive adhesive layer
50 peel liner

Claims (18)

A single-sided adhesive pressure-sensitive adhesive sheet used for attaching to a graphite sheet,
And a pressure-sensitive adhesive layer formed on one surface of the base material,
The substrate contains a black layer,
The 60 deg. Gloss value of the back surface of the pressure-sensitive adhesive sheet is 10 or less,
Wherein the adhesive sheet has a light transmittance of 12 to 30%. The method according to claim 1,
The base material has a resin film layer and a black layer,
Wherein the pressure-sensitive adhesive sheet comprises the pressure-sensitive adhesive layer, the resin film layer, and the black layer laminated in this order. 3. The method of claim 2,
Wherein the thickness of the black layer is 2 占 퐉 or less. The method according to claim 2 or 3,
Wherein the back surface of the pressure-sensitive adhesive sheet has a lightness L ^* defined by the L ^* a ^* b ^* colorimetric system of 40 or less. 5. The method according to any one of claims 2 to 4,
The substrate further includes a mat layer,
Wherein the substrate has a laminated structure in which the resin film layer, the black layer and the mat layer are laminated in this order. 6. The method of claim 5,
Wherein the mat layer contains a particulate mat member. The method according to claim 5 or 6,
Wherein the mat layer has a thickness of 2 m or less. 8. The method according to any one of claims 1 to 7,
Wherein the total thickness of the pressure sensitive adhesive sheet is 30 占 퐉 or less. 9. The method according to any one of claims 1 to 8,
A pressure sensitive adhesive sheet disposed within a portable electronic device. 10. The method according to any one of claims 1 to 9,
Wherein the pressure-sensitive adhesive layer contains an acrylic polymer in a proportion exceeding 50% by weight of the polymer component contained in the pressure-sensitive adhesive layer,
The acrylic polymer contains, as a monomer component, an alkyl (meth) acrylate represented by formula (1) in a proportion of 70 wt% or more.
CH ₂ = C (R ¹ ) COOR ² (1)
(Wherein R ¹ is a hydrogen atom or a methyl group, and R ² is a straight chain alkyl group having 1 to 20 carbon atoms) 11. The method of claim 10,
Wherein the alkyl (meth) acrylate is n-butyl acrylate and 2-ethylhexyl acrylate. 12. The method of claim 11,
Wherein the 2-ethylhexyl acrylate is contained in the monomer component in a proportion lower than that of n-butyl acrylate. 13. The method according to any one of claims 10 to 12,
The acrylic polymer may further contain a functional group-containing monomer as the monomer component,
The functional group-containing monomer is at least one monomer selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, (Meth) acrylate, and 4-hydroxybutyl (meth) acrylate. 14. The method according to any one of claims 1 to 13,
Wherein the pressure-sensitive adhesive layer contains a rosin-based tackifier resin having a softening point of 100 占 폚 or more and 180 占 폚 or less as a tackifier resin,
Wherein the content of the tackifier resin is 20 to 60 parts by weight based on 100 parts by weight of the base polymer of the pressure-sensitive adhesive layer. 15. The method according to any one of claims 1 to 14,
Wherein the base material comprises a polyethylene terephthalate-based resin film layer. 16. The method according to any one of claims 1 to 15,
Wherein the black layer contains carbon black as a black pigment. 17. The method according to any one of claims 1 to 16,
Wherein the thickness of the substrate is 9 占 퐉 or less. 18. A pressure-sensitive adhesive sheet with a release liner comprising the pressure-sensitive adhesive sheet according to any one of claims 1 to 17 and a release liner for protecting the adhesive surface of the pressure-sensitive adhesive sheet.

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