CN106957611B - Single-sided adhesive pressure-sensitive adhesive sheet - Google Patents

Abstract

Provided is a one-sided adhesive pressure-sensitive adhesive sheet, the appearance quality of which is further improved. According to the present invention, there is provided a one-sided adhesive pressure-sensitive adhesive sheet comprising a base film, a pressure-sensitive adhesive layer provided on a first surface of the base film, and a colored layer provided on a second surface of the base film. The back surface of the adhesive sheet is a matte-treated surface having alcohol resistance.

Description

Single-sided adhesive pressure-sensitive adhesive sheet

Technical Field

The present invention relates to a single-sided adhesive pressure-sensitive adhesive sheet.

The present application claims priority based on japanese patent application 2015-252605 filed 24/12/2015 and japanese patent application 2016-112606 filed 6/2016, the entire contents of which are incorporated by reference into this specification.

Background

In general, an adhesive (also referred to as a pressure-sensitive adhesive, hereinafter) is in a soft solid (viscoelastic body) state in a temperature range around room temperature, and has a property of being easily adhered to an adherend by pressure. Because of these properties, adhesives are widely used for the purpose of joining, fixing, protecting, etc. various members in the form of a substrate-attached adhesive sheet. For example, in portable electronic devices such as mobile phones, the adhesive sheet having the above-described structure is used for the purpose of protecting a graphite sheet provided for heat dissipation, imparting design properties, and the like (patent document 1). Specifically, the adhesive sheet for this use has a structure in which an adhesive layer is disposed on one surface of a base film on which a colored layer is formed. Patent document 2 is a prior art document relating to an adhesive sheet having a fingerprint treatment resistant layer.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2013-203965

Patent document 2: japanese laid-open patent application publication No. 2013-166891

Disclosure of Invention

Problems to be solved by the invention

An adhesive sheet provided with a colored layer for the purpose of design and the like is generally required to have excellent appearance. Therefore, this adhesive sheet takes the following measures: a fingerprint-resistant layer or the like is provided on the back surface of the pressure-sensitive adhesive sheet, so that fingerprints or the like adhering to the pressure-sensitive adhesive sheet during the production process or the like are not conspicuous (see patent document 2). However, although the fingerprint-resistant layer is effective in reducing the visibility of fingerprint traces, it does not completely remove fingerprint traces, and therefore, when significant fingerprint traces are deposited, it is necessary to erase the fingerprint traces using a solvent such as alcohol. From this point of view, it is desirable that the back surface of the adhesive sheet is an alcohol-resistant surface. Since the conventional colored layer, fingerprint-resistant layer, and the like may be damaged by cleaning with alcohol, the back surface of the pressure-sensitive adhesive sheet is an alcohol-resistant surface, and thus fingerprint marks can be erased with alcohol regardless of the material of the colored layer and the like. This improves the appearance quality.

However, the requirements for the quality of the appearance are being further upgraded. Specifically, when removing fingerprint marks using alcohol, the alcohol used for wiping may become visible as wiping marks. Such a wiping mark is a slight change in appearance at a level that has not been problematic in the past, but if it can be eliminated, the appearance quality of the pressure-sensitive adhesive sheet can be further improved, which is useful.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a pressure-sensitive adhesive sheet which can further improve the appearance quality.

Means for solving the problems

According to the present invention, there is provided a one-sided adhesive pressure-sensitive adhesive sheet comprising a base film, a pressure-sensitive adhesive layer provided on a first surface of the base film, and a colored layer provided on a second surface of the base film. The back surface of the adhesive sheet is a matte-treated surface having alcohol resistance.

As described above, by providing the back surface of the pressure-sensitive adhesive sheet with an alcohol-resistant surface, fingerprint marks can be erased using alcohol regardless of the material of the colored layer or the like. Further, by forming the back surface of the pressure-sensitive adhesive sheet as a matte finish surface, volatilization of alcohol used for cleaning can be promoted, and wiping marks become inconspicuous. Therefore, according to the present invention, the appearance quality of the adhesive sheet can be further improved.

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, an alcohol-resistant layer is provided on the surface of the colored layer. With such a configuration, the back surface of the pressure-sensitive adhesive sheet can exhibit excellent alcohol resistance.

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, the alcohol-resistant layer contains a particulate matting material. With this configuration, the matte finish of the back surface of the adhesive sheet is preferably achieved.

In a preferred embodiment of the pressure-sensitive adhesive sheet disclosed herein, the alcohol-resistant layer has a thickness of 2 μm or less. With such a configuration, it is possible to suppress an increase in thickness of the pressure-sensitive adhesive sheet and to achieve a desired improvement in appearance quality. This is a preferable feature in applications requiring a reduced thickness and weight.

In a preferred embodiment of the technology disclosed herein, the 60 ° gloss value of the back surface of the adhesive sheet is 10 or less. With this configuration, the appearance quality of the pressure-sensitive adhesive sheet is further improved.

In a preferred embodiment of the technology disclosed herein, the adhesive sheet has a luminance L defined by the chromaticity system la a b on the back surface thereof^*Is 40 or less. The pressure-sensitive adhesive sheet having the above brightness can have a color tone suitable for various applications where black is desired. The adhesive sheet having the above brightness is preferably used for application to a graphite sheet. For example, the 60 DEG gloss value of the back surface is 10 or less and the brightness L^*A pressure-sensitive adhesive sheet of 40 or less can exhibit a black color with a rich feeling of reduced gloss, and therefore can be particularly preferably used for applications requiring such designability.

Further, according to the present invention, there is provided a release-lined pressure-sensitive adhesive sheet 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. Since the back surface of the pressure-sensitive adhesive sheet is formed as a matte finish surface, the pressure-sensitive adhesive sheet is easy to unwind when it is unwound from a roll. Therefore, the interlayer breakage between the base film and the colored layer during unwinding can be prevented.

Further, the present invention provides a release-lined pressure-sensitive adhesive sheet including a pressure-sensitive adhesive sheet having single-sided adhesiveness and a release liner for protecting the adhesive surface of the pressure-sensitive adhesive sheet. The adhesive sheet comprises: the adhesive layer is arranged on the first surface of the base material film, and the coloring layer is formed on the second surface of the base material film. The back surface of the pressure-sensitive adhesive sheet is a matte-treated surface.

Since the back surface of the pressure-sensitive adhesive sheet is formed as a matte finish surface as described above, the pressure-sensitive adhesive sheet is easy to unwind when it is unwound from a roll. Therefore, the interlayer breakage between the base film and the colored layer during unwinding can be prevented. Specifically, in an adhesive sheet in which a colored layer is provided on the surface of a base film, a primer layer is generally provided between the base film and the colored layer in order to improve the adhesion (anchoring property) of the colored layer. However, for example, when the thickness of the pressure-sensitive adhesive sheet is reduced, the colored layer may be formed directly on the base film without providing the primer layer. In this case, when the pressure-sensitive adhesive sheet is wound into a roll (pressure-sensitive adhesive sheet roll) with the adhesive surface of the pressure-sensitive adhesive sheet protected by the release liner and the pressure-sensitive adhesive sheet is unwound from the roll, interlayer failure occurs between the base film and the colored layer due to adhesion between the back surface of the release liner (the surface opposite to the surface protecting the adhesive surface of the pressure-sensitive adhesive sheet) and the back surface of the pressure-sensitive adhesive sheet. With the configuration of the present invention in which the back surface of the pressure-sensitive adhesive sheet is made to be a matte finish surface, the contact area between the back surface of the pressure-sensitive adhesive sheet and the back surface of the release liner is reduced, and interlayer damage between the base film and the colored layer when unwinding from a roll can be prevented.

In a preferred embodiment of the technology disclosed herein, the total thickness of the pressure-sensitive adhesive sheet (which may be a pressure-sensitive adhesive sheet constituting a release liner-equipped pressure-sensitive adhesive sheet) is 30 μm or less. For such a thin adhesive sheet, improvement in appearance quality is preferably achieved by applying the technology disclosed herein. In addition, the adhesive sheet having a small thickness as described above can effectively prevent interlayer fracture between the base film and the colored layer by the technique disclosed herein. This is because the elimination of the undercoat layer disposed between the base film and the colored layer can be one means for reducing the thickness.

The adhesive sheet disclosed herein has improved appearance quality. Therefore, it is preferably used as an adhesive sheet to be attached to a graphite sheet required to have predetermined design and appearance. Specifically, the pressure-sensitive adhesive sheet is suitable as a pressure-sensitive adhesive sheet used for a graphite sheet disposed in a portable electronic device such as a mobile phone or a smartphone. Therefore, the adhesive sheet provided by the present specification can be laminated on a graphite sheet disposed in a portable electronic device. From the same viewpoint, the adhesive sheet disclosed herein is preferably used as an adhesive sheet to be attached to a ferrite sheet. Specifically, the pressure-sensitive adhesive sheet is suitable for use as a ferrite sheet to be attached to a portable electronic device such as a mobile phone or a smartphone. Therefore, the adhesive sheet provided by the present specification can be laminated on a ferrite sheet disposed in a portable electronic device.

Drawings

Fig. 1 is a sectional view schematically showing one configuration example of an adhesive sheet.

Description of the reference numerals

1 pressure-sensitive adhesive sheet

1A adhesive surface

1B back side

10 base material film

One surface (adhesive layer side surface) of the base film 10A

10B the other surface (backside surface) of the base film

20 adhesive layer

30 coloured layer

40 topcoat

50 Release liner

Detailed Description

Preferred embodiments of the present invention will be described below. It should be noted that matters necessary for carrying out the present invention other than the matters specifically mentioned in the present specification can be understood by those skilled in the art from the teaching of the implementation of the invention described in the present specification and the technical common general knowledge at the time of application. The present invention can be implemented according to the contents disclosed in the present specification and the common general knowledge in the art. In the following drawings, members and portions that perform the same function will be described with the same reference numerals, and redundant description thereof may be omitted or simplified. The embodiments shown in the drawings are schematic for the purpose of clearly illustrating the present invention, and do not necessarily show the size or scale of the psa sheet of the present invention actually provided as a product.

In the present specification, the "pressure-sensitive adhesive" refers to a material that is in a soft solid (viscoelastic body) state in a temperature range around room temperature and has a property of easily adhering to an adherend by pressure, as described above. As used herein, an adhesive is exemplified by "c.a. dahlquist," adhesive: fundamental and Practice ", McLaren&Sons, (1966) P.143 "can generally be of a type having a complex tensile modulus E^*(1Hz)<10⁷dyne/cm²A material having the above properties (typically a material having the above properties at 25 ℃).

< construction of adhesive sheet >

The pressure-sensitive adhesive sheet disclosed herein is a pressure-sensitive adhesive sheet with a substrate and one-sided adhesion, which is a system having a pressure-sensitive adhesive layer on one surface of a substrate film (support). The concept of the adhesive sheet as referred to herein may cover articles called adhesive tapes, adhesive labels, adhesive films, etc. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or a sheet. Alternatively, the adhesive sheet may be processed into various shapes.

The adhesive sheet disclosed herein may be an adhesive sheet having a cross-sectional structure schematically shown in fig. 1, for example. The pressure-sensitive adhesive sheet 1 shown in fig. 1 includes: a base film 10, a pressure-sensitive adhesive layer 20 provided on a first surface 10A of the base film 10, and a colored layer 30 provided on a second surface 10B of the base film 10. Further, a top coat layer 40 is provided on the surface of the colored layer 30. In this psa sheet 1, the surface of the psa layer 20 is the adhesive surface 1A of the psa sheet 1. The pressure-sensitive adhesive sheet 1 before use has a structure in which the pressure-sensitive adhesive layer 20 is protected by a release liner 50 serving as a release surface 50B on the pressure-sensitive adhesive layer 20 side. When the release liner 50-attached pressure-sensitive adhesive sheet 1 is produced in a roll (pressure-sensitive adhesive sheet roll) form for the purposes of transportation, storage, and the like, the outer surface 50A (surface on the opposite side of the release surface 50B) of the release liner 50 comes into contact with the back surface 1B (surface 40A of the topcoat layer 40 in the present embodiment) of the pressure-sensitive adhesive sheet.

The topcoat layer 40 disposed on the surface of the colored layer 30 constitutes the back surface (outermost surface) 1B of the adhesive sheet 1. In this embodiment, the top coat layer 40 is a matte layer that imparts matte properties to the back surface 1B of the adhesive sheet 1, but is not limited thereto, and may be an alcohol-resistant layer having alcohol resistance, and may preferably be a layer having both matte properties and alcohol resistance (alcohol-resistant matte layer). It is technically possible to make the surface of the colored layer 30 a matte finish surface without forming a topcoat layer, or to impart alcohol resistance to the colored layer 30, and therefore, the topcoat layer 40 may be omitted in this case.

< characteristics of adhesive sheet, etc. >

The back surface of the adhesive sheet disclosed herein is a matte finish surface. By applying the matte finish to the back surface of the adhesive sheet, the adhesive sheet is easily unwound from a roll, and interlayer damage between the base film and the colored layer can be prevented. In addition, when alcohol resistance is imparted to the back surface of the pressure-sensitive adhesive sheet, the wiping mark of alcohol is not conspicuous, and the appearance quality is improved. In the present specification, the matte finish surface refers to a surface obtained by performing a matte finish (surface treatment) such as embossing or sandblasting, or an active matte finish such as matte layer formation. A surface having a gloss value of 60 ℃ which is lower than that before the matting treatment after the matting treatment is a typical example of the matte-treated surface described herein.

In a preferred embodiment, the back surface of the adhesive sheet is an alcohol-resistant surface (alcohol-resistant surface). Here, the back surface of the pressure-sensitive adhesive sheet has alcohol resistance means a surface whose change in appearance (typically dissolution) is suppressed when exposed to alcohol, and typically is a surface that is preferably evaluated as "acceptable" in an alcohol resistance evaluation test measured by the method described in the examples described later. Therefore, when a fingerprint mark is adhered to the back surface of the adhesive sheet, the fingerprint mark can be erased by using alcohol regardless of the material of the colored layer.

In a preferred embodiment, the 60 ° gloss value of the back surface of the adhesive sheet is 10 or less. This further improves the appearance quality of the pressure-sensitive adhesive sheet. Further, the adhesive sheet is more easily unwound from the roll form, and the interlayer breakage between the base film and the colored layer can be more reliably prevented. The 60 ° gloss value of the back surface of the psa sheet is more preferably 7 or less, and still more preferably 6 or less (typically 5.5 or less). The lower limit of the 60 ° gloss value is not particularly limited, and is preferably 1 or more, and preferably 2 or more (for example, 3 or more, and typically 3.5 or more) from the viewpoint of balance with design and color tone. The 60 ° Gloss value of the back surface of the adhesive sheet can be measured using a commercially available Gloss meter (for example, trade name "high Gloss Checker IG-410" manufactured by horiba ltd.) under the condition of measuring the angle of 60 °. The same applies to the following examples.

In a preferred embodiment, the back surface of the adhesive sheet has a luminance L defined by the chromaticity system la b^*It may be 50 or less (e.g., 40 or less, typically 35 or less). The above-mentioned brightness L^*Preferably 30 or less. The pressure-sensitive adhesive sheet having the above brightness can have a color tone suitable for various applications where black is desired. The adhesive sheet having the above brightness is preferably used for application to a graphite sheet. For the above brightness L^*The lower limit of (b) is not particularly limited, and may be about 15 or more (for example, 20 or more) from the viewpoint of appearance and the like. In a particularly preferred embodiment, the rear surface has a 60 DEG gloss value of 10 or less (e.g., 3 to 7, typically 3.5 to 5.5) and a brightness L ^*40 or less (e.g., 15 to 35, typically 20 to 30). The pressure-sensitive adhesive sheet having the back surface described above exhibits a black color with a rich feeling of thickness with suppressed gloss, and therefore can be particularly preferably applied to applications requiring such designability. The pressure-sensitive adhesive sheet having the back surface can have a color tone compatible with the surrounding members (for example, a battery) thereof by being laminated on a graphite sheet, for example.

L of the back surface of the adhesive sheet^*a^*b^*Chroma a defined by the chromaticity system^*The range is not particularly limited, and is preferably ± 15 (for example, ± 5, typically ± 2) in consideration of the coordination between the portion (which may be a member) to which the adhesive sheet is applied and the color tone around the portion. Chroma b^*The range is not particularly limited, but is preferably ± 15 (for example, ± 10, typically, ± 5). In this specification, the specification is to be regarded as illustrativeIn the above description, the range of "+" X "is used in the meaning of the range of-X to + X.

In this specification, L is^*a^*b^*As the color system, a color system according to the regulations recommended by the International Commission on illumination in 1976 or the regulations of JIS Z8729 was used. In particular, with respect to L^*a^*b^*The adhesive sheet back surface may be measured at a plurality of positions (for example, 5 points or more) using a color difference meter (trade name "CR-400" Minolta co., ltd.; color difference meter), and the average value may be used. The same applies to the following examples.

The light transmittance of the adhesive sheet disclosed herein is preferably 20% or less. Thus, the adhesive sheet exhibits good light-shielding properties. The light transmittance is preferably 15% or less, more preferably 10% or less, and further preferably less than 10% (for example, 7% or less, and typically 5% or less). In a particularly preferred embodiment, the light transmittance may be less than 1% (e.g., less than 0.5%, typically less than 0.1%) or may be substantially 0% from the viewpoint of obtaining sufficient light-shielding properties. The light transmittance may be 1% or more, or 2% or more. Such a pressure-sensitive adhesive sheet can appropriately (appropriately) reflect the color tone of an adherend (e.g., a graphite sheet), and can provide desired color tone, texture, and design properties.

The light transmittance of the pressure-sensitive adhesive sheet is determined by perpendicularly irradiating one surface of the pressure-sensitive adhesive sheet with light having a wavelength of 380 to 780nm using a commercially available spectrophotometer, and measuring the intensity of the light transmitted through the other surface. As the spectrophotometer, for example, a spectrophotometer manufactured by hitachi (device name "spectrophotometer model U4100") can be used. The same applies to the following examples.

The 180-degree peel strength of the adhesive sheet disclosed herein is preferably 0.5N/20mm or more. The adhesive sheet exhibiting the above characteristics can be favorably adhered to an adherend (e.g., a graphite sheet). The peel strength is more preferably 1.0N/20mm or more, and still more preferably 2.0N/20mm or more. In another preferred embodiment, the peel strength is 5.0N/20mm or more, more preferably 8.0N/20mm or more, and still more preferably 12.0N/20mm or more, while the adhesiveness to an adherend is regarded as important. The peel strength referred to herein means a 180-degree peel strength (180-degree peel adhesion) with respect to a stainless steel plate.

The 180 degree peel strength can be measured as follows. Specifically, a one-sided pressure-sensitive adhesive tape (trade name "No. 31B", manufactured by ritonao electric corporation, having a total thickness of 50 μm) was attached to the back surface of the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet was cut into a size of 20mm in width and 100mm in length, and the thus-obtained measurement sample was subjected to pressure-bonding of the adhesive surface of the measurement sample to the surface of a stainless steel plate (SUS304BA plate) by reciprocating a 2kg roller 1 time at 23 ℃ and 50% RH. After leaving in this environment for 30 minutes, the molded article was measured using a universal tensile compression tester according to JIS Z0237: 2000, the peel strength (N/20mm) was measured under the conditions of a tensile rate of 300 mm/min and a peel angle of 180 degrees. As the universal tensile compression tester, for example, "tensile compression tester, TG-1 kN" manufactured by Minebea Co., Ltd. The measurement was carried out in the same manner as in examples described below.

The total thickness of the pressure-sensitive adhesive sheet disclosed herein (which may include the pressure-sensitive adhesive layer, the base film, the colored layer, and the top coat layer, but does not include the release liner.) is not particularly limited, and is preferably about 2 μm or more (e.g., 3 μm or more), and is preferably about 150 μm or less (e.g., 100 μm or less, typically 50 μm or less). In a preferred embodiment, the total thickness of the pressure-sensitive adhesive sheet is about 30 μm or less (for example, 20 μm or less, typically 10 μm or less), and the total thickness may be 7 μm or less. A pressure-sensitive adhesive sheet having a small thickness is advantageous in terms of reduction in thickness, size, weight, resource conservation, and the like of products to which the pressure-sensitive adhesive sheet is applied. When the adhesive sheet disclosed herein is used for application to a graphite sheet, the heat dissipation effect of the graphite sheet can be sufficiently exhibited by making the adhesive sheet thin. In another preferred embodiment, the total thickness of the pressure-sensitive adhesive sheet may be 10 μm or more, and more preferably 25 μm or more (for example, 45 μm or more, and typically 60 μm or more), from the viewpoint of handling properties and obtaining sufficient pressure-sensitive adhesive properties (for example, adhesive force) by increasing the thickness of the pressure-sensitive adhesive layer.

< substrate film >

In the psa sheet disclosed herein, the substrate film (support substrate film) for supporting (supporting) the psa layer is typically a resin film containing a resin material as a main component (e.g., a component contained in the substrate film in an amount exceeding 50 wt%). In the present specification, the term "resin film" typically means a resin film that is substantially non-foamed. That is, the resin film in the present specification may be a resin film in which air bubbles are not substantially present in the resin film (non-porous resin film). Therefore, the resin film is a concept different from a so-called foam film. The resin film is typically a substantially nonporous film, and is a concept different from a so-called nonwoven fabric or textile. A substrate film that does not include a porous layer such as a foam, a nonwoven fabric, or a woven fabric, that is, a substrate film composed of a non-porous layer may be preferably used.

Resin films generally tend to have superior mechanical strength such as tensile strength as compared with foams, nonwoven fabrics, and woven fabrics. In addition, the workability (e.g., punching workability) is excellent. Therefore, an adhesive sheet using a base film comprising a resin film is advantageous in terms of processability, dimensional accuracy, and handling properties. Further, a substrate including such a resin film can also be preferably used as a substrate film in the technology disclosed herein from the viewpoints of dimensional stability, thickness accuracy, economy (cost), and the like.

Suitable examples of the resin material constituting the resin film disclosed herein include polyolefin-based resins and polyester-based resins. The polyolefin resin is a resin containing a polyolefin in a proportion of more than 50% by weight. Similarly, the polyester resin is a resin containing a polyester at a ratio exceeding 50% by weight. Examples of the polyolefin resin film include Polyethylene (PE) resins, polypropylene (PP) resins, ethylene-propylene copolymers, and ethylene-butene copolymers. Examples of the polyester resin include polyethylene terephthalate (PET) resin, polybutylene terephthalate (PBT) resin, polyethylene naphthalate resin, and polybutylene naphthalate resin. Among them, from the viewpoint of the anchoring property (particularly, the anchoring property of the acrylic pressure-sensitive adhesive layer), a polyester-based resin is preferable, and from the viewpoint of the strength and the processability, a PET-based resin is particularly preferable.

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

As the base film (typically, a resin film), a transparent film (typically, a transparent resin film) can be preferably used. The substrate film may be substantially free of colorant. Here, the base film (typically, a resin film) does not substantially contain a colorant, meaning that the content of the colorant is less than 1% by weight, preferably less than 0.1% by weight. Alternatively, the base film in the art disclosed herein may be colored in a color such as black or white (e.g., milky white) in order to provide a psa sheet including the base film with desired design properties and optical properties (e.g., light-shielding properties). The coloring may be performed by, for example, adding a known organic or inorganic colorant (such as a pigment or a dye) to a material (typically, a resin material) constituting the base film.

The substrate film disclosed herein may be a single layer structure, or may be a film having a multilayer structure of 2, 3 or more layers. The base film is preferably a single-layer structure from the viewpoint of shape stability. In the case of a multilayer structure, at least one layer (preferably all layers) is preferably a layer having a continuous structure of the above resin (for example, a polyester resin). The method for producing the base film (typically, a resin film) is not particularly limited, and any conventionally known method may be suitably used. For example, conventionally known conventional film forming methods such as extrusion molding, inflation molding, T-die casting molding, calender roll molding, and the like can be suitably used.

The surface of the base film may be subjected to conventionally known surface treatment such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of an undercoating agent (formation of an undercoating layer). Such surface treatment may be treatment for improving adhesion between the base film and the pressure-sensitive adhesive layer and adhesion between the base film and the colored layer. It should be noted that the technology disclosed herein can be preferably implemented as follows: a mode in which the base film is in direct contact with the adhesive layer and/or the base film is in direct contact with the colored layer without forming the undercoat layer between the base film and the adhesive layer and/or between the base film and the colored layer. The adhesive sheet thus constituted can be made thinner.

The thickness of the base film is not particularly limited. The thickness of the base film of one embodiment may be 30 μm or less, for example. The thickness of the base film is reduced, whereby the pressure-sensitive adhesive sheet is also reduced in thickness, and the pressure-sensitive adhesive sheet is further advantageous in terms of reduction in thickness, size, weight, resource conservation, and the like of products to which the pressure-sensitive adhesive sheet is applied. In addition, when the adhesive sheet disclosed herein is used for a heat sink (typically a graphite sheet), the heat dissipation efficiency of the heat sink can be improved. The thickness of the base film is preferably 12 μm or less, more preferably 9 μm or less (for example, 7 μm or less, typically 5 μm or less). In particular, when the miniaturization, weight reduction, or the like is important, the thickness of the base film is preferably 3 μm or less (for example, 2 μm or less). The thickness of the base film is preferably about 0.5 μm or more (for example, 1 μm or more) from the viewpoint of handling property, processability, and the like. In another embodiment, the thickness of the base film exceeds 30 μm (for example, 35 μm or more) from the viewpoint of handling property and the like. The thickness of the base film of this embodiment is preferably about 200 μm or less (for example, 100 μm or less, typically 50 μm or less).

< coloring layer >

The colored layer provided on the second surface (surface opposite to the pressure-sensitive adhesive layer-side surface) of the base film may be, for example, a black printed layer printed on the surface (second surface) of the base film. An adhesive sheet having a black layer as a coloring layer can be preferably used for, for example, application to a graphite sheet.

The colored layer is typically formed by applying a composition for forming a colored layer containing a colorant and a binder to a base film. As the binder, materials known in the field of coating or printing can be used without particular limitation. Examples of such a material include polyurethane, phenol resin, epoxy resin, urea melamine resin, and polymethyl methacrylate. The composition for forming a colored layer may be, for example, a solvent type, an ultraviolet curing type, a thermosetting type, or the like. The colored layer can be formed by any means conventionally used for forming colored layers without any particular limitation. For example, a method of forming a colored layer (printed layer) by printing such as gravure printing, flexo printing, and offset printing can be preferably used.

The colored layer may have a single-layer structure consisting of 1 layer as a whole, or may have a multi-layer structure including 2, 3 or more sub-colored layers. The colored layer having a multilayer structure including 2 or more sub-colored layers can be formed by, for example, repeating application (e.g., printing) of the composition for forming a colored layer. The coloring agent contained in each of the subsidiary coloring layers may be the same in color or different in amount of blending. In the colored layer for imparting light-shielding properties, it is particularly significant to form a multilayer structure from the viewpoint of preventing the occurrence of pinholes and improving the reliability of light leakage prevention.

As the coloring agent used for coloring the colored layer, a known pigment or dye that matches the target color can be appropriately selected. Although not particularly limited, examples of the white pigment include titanium dioxide, zinc white, and lead white. Examples of the black pigment include carbon black, acetylene black, pine smoke, and graphite. These can be used alone in 1 kind, also can be combined with more than 2 kinds.

The content of the colorant is set in accordance with the desired color tone, texture, and the like, and is not limited to a specific range, and is preferably about 1% by weight or more, and preferably 2% by weight or more (for example, 5% by weight or more, and typically 15% by weight or more) in the colored layer. The content of the colorant is preferably about 65 wt% or less, and preferably 30 wt% or less (for example, 15 wt% or less, and typically 8 wt% or less) in the colored layer.

The thickness of the entire colored layer is usually preferably 0.1 μm or more, more preferably 0.5 μm or more, and further preferably 0.7 μm or more (for example, 0.8 μm or more, and typically 1 μm or more). In another embodiment, from the viewpoint of obtaining sufficient light-shielding properties, the thickness of the entire colored layer is preferably 2 μm or more (for example, 3 μm or more, and typically 4 μm or more). The thickness of the entire colored layer is usually preferably 10 μm or less, more preferably 7 μm or less, and still more preferably 5 μm or less (for example, 3 μm or less, and typically 2 μm or less). In the colored layer including two or more sub-colored layers, the thickness of each sub-colored layer is preferably about 0.5 to 2 μm.

< topcoat >

The top coat layer disclosed herein is a layer formed on the surface of the colored layer, and is a layer constituting the back surface of the adhesive sheet. The topcoat layer is disposed in the adhesive sheet so as to cover the surface of the colored layer. Since the color tone and design of the back surface side of the adhesive sheet are realized by the colored layer, the topcoat layer is typically transparent (including translucent). In addition, the surface (outer surface) of the topcoat layer is preferably a matte finish surface, in which case the topcoat layer may be referred to as a matte layer in other words. The matte layer may be a top coat layer (layer having a matte finish) whose surface is subjected to a surface treatment such as embossing or sandblasting, or may be a matte layer having a matte property when formed on the surface of the colored layer by coating or the like. The top coat layer is preferably a matte layer from the viewpoint of having a function of protecting the colored layer as well.

In a preferred form, the topcoat includes a matte layer. Typically, the topcoat is preferably a matte layer. Here, the matte layer is a layer that reduces the gloss of the surface of the colored layer forming the layer. This improves the appearance quality and prevents interlayer damage between the base film and the colored layer when the adhesive sheet is unwound from a roll. The presence or absence and degree of the reduction in gloss can be grasped by measuring the 60 ° gloss value. The topcoat surface may be the back surface of the adhesive sheet, and therefore the 60 ° gloss value of the topcoat surface may take a value within the range shown above as the 60 ° gloss value of the back surface of the adhesive sheet.

The topcoat (matte layer) disclosed herein preferably has matting properties by its composition. For example, the matting layer may be a layer comprising a matting material. This makes it possible to impart matting properties to the top coat layer without performing additional surface treatment. The matting material is typically in the form of particles, and a transparent (typically colorless and transparent) material is preferably used. The particle shape of the matting material is not particularly limited, and may be spherical or the like.

The matting material may be either organic or inorganic particles, or a combination of both. Examples of the organic particles include acrylic resin particles such as polymethyl methacrylate 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, and talc. These can be used alone in 1 kind, also can be combined with more than 2 kinds. Among them, acrylic resin particles, urethane resin beads, and silica particles are preferable.

The average particle diameter of the matting material is not limited to a specific range, and is suitably about 0.1 μm or more, and preferably about 0.5 μm or more (for example, 1 μm or more, and typically more than 1 μm), because it is determined depending on the degree of matting required, the thickness of the matting layer, and the like. The average particle size is suitably 20 μm or less, preferably about 8 μm or less (for example, 3 μm or less, typically 2 μm or less). From the viewpoint of sufficiently exhibiting matting properties, the average particle diameter of the matting material is preferably at least half the thickness of the matting layer, and is preferably the same as or greater than the thickness of the matting layer. From the viewpoint of appearance and coatability, the average particle diameter of the matte material is preferably about 10 times or less (e.g., 5 times or less, typically 3 times or less) the thickness of the matte layer. The average particle diameter of the matting material is a particle diameter in which the cumulative particle diameter on a volume basis in the particle size distribution obtained by measurement by a laser diffraction/scattering method reaches 50%, that is, a 50% volume average particle diameter (50% median diameter).

The content of the matting material is set in accordance with the degree of matting required, the particle size of the matting material, and the like, and is not limited to a specific range, and is suitably about 0.5% by weight or more, preferably 1% by weight or more (for example, 2% by weight or more, and typically 3% by weight or more) in the matting layer. The content of the matting material is preferably about 40 wt% or less, and preferably 20 wt% or less (for example, 10 wt% or less, and typically 8 wt% or less) in the matting layer.

In a preferred form, the topcoat includes an alcohol-resistant layer. Typically, the topcoat is preferably an alcohol resistant layer. Here, the alcohol-resistant layer is a layer that imparts alcohol resistance to the adhesive sheet (typically, the back surface of the adhesive sheet). Specifically, the alcohol-resistant layer is a layer evaluated as "acceptable" in an alcohol resistance evaluation test described later, which is performed in a state of being disposed on the back side of the adhesive sheet. The alcohol-resistant layer can be obtained by selecting the kind and amount of the resin component, solvent, dispersant and other additive components contained in the composition for forming the alcohol-resistant layer. As the resin component, one having excellent alcohol resistance may be selected from among resin components that can be contained in a topcoat layer described later according to the common technical knowledge. Commercially available products include 9000PL series and 9100PL series (both solvent-based PET inks) manufactured by JUJO CHEMICAL co. The above-mentioned commercially available product may contain a colorant, and thus, for example, product number "# 9092" (black ink) may also be used as a material for forming a colored layer having alcohol resistance.

The top coat layer (which may be any one of a matte layer, an alcohol-resistant layer, and an alcohol-resistant matte layer having both functions of the matte layer and the alcohol-resistant layer) may contain other additive components such as a resin component and a dispersant. When the top coat is clear, the top coat is substantially free of colorant. Here, the top coat layer contains substantially no 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 top coat layer include polyurethane resin, phenol resin, epoxy resin, urea melamine resin, silicone resin, phenoxy resin, methacrylic resin, acrylic resin, polyarylate resin, polyester resin, polyolefin resin, polystyrene resin, styrene-acrylic resin, styrene-maleic acid resin, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polycarbonate, cellulose, polyacetal, and alkyd resin. The resin component can be used alone in 1 or a combination of 2 or more. The resin composition for forming the top coat layer (resin composition for forming a top coat layer) may be a solvent-based composition, a thermosetting composition or an ultraviolet-curable composition, and is preferably a thermosetting type or an ultraviolet-curable type from the viewpoint of layer formability and heat resistance.

The method for forming a top coat layer using the above-mentioned composition for forming a top coat layer is not particularly limited, and various printing treatment methods can be employed. The printing method is not particularly limited, and various known or conventional methods such as offset printing, screen printing, relief printing, flexo printing, and gravure printing can be suitably used. Specifically, a top coat layer can be formed by dissolving or dispersing solid components (typically, a resin component and a dispersant) constituting the composition in an appropriate solvent, and printing the obtained composition on the colored layer by an appropriate method among the above-mentioned printing methods.

The topcoat typically has a single layer structure. Alternatively, the topcoat layer may also have a multilayer structure including a matte layer and/or an alcohol-resistant layer. When the top coat layer has the matte layer and the alcohol-resistant layer, the alcohol-resistant layer is preferably disposed on the outermost surface. For example, the top coat layer may have a release treatment layer on the outermost surface (back surface of the pressure-sensitive adhesive sheet). In addition, from the viewpoint of reducing the thickness of the pressure-sensitive adhesive sheet, it is preferable that no undercoat layer is provided between the top coat layer and the colored layer, but the undercoat layer and the like may be provided to improve interlayer adhesion.

In view of the impartation of predetermined characteristics (e.g., matting property, alcohol resistance, etc.) and coating property, the thickness of the top coat layer is preferably about 0.1 μm or more, and more preferably about 0.2 μm or more (e.g., 0.3 μm or more, typically 0.5 μm or more). From the viewpoint of reducing the thickness, the thickness is preferably about 5 μm or less, and preferably about 3 μm or less (for example, 2 μm or less, and typically 1.5 μm or less).

Although not particularly limited, in the pressure-sensitive adhesive sheet disclosed herein, the total thickness of the layers other than the pressure-sensitive adhesive layer (the total thickness of the non-pressure-sensitive adhesive layer, typically the total thickness of the base film, the colored layer, and the topcoat layer) is, for example, 40 μm or less, preferably 30 μm or less, and more preferably 20 μm or less. The total thickness of the non-pressure-sensitive adhesive layer is more preferably 10 μm or less, and particularly preferably 5 μm or less (for example, 4.5 μm or less), from the viewpoint of limiting the total thickness of the pressure-sensitive adhesive sheet to a predetermined value or less and obtaining high adhesive performance. The lower limit of the total thickness of the non-pressure-sensitive adhesive layer is not particularly limited, but is usually suitably 2 μm or more, preferably 3 μm or more (for example, 3.5 μm or more), from the viewpoint of processability of the pressure-sensitive adhesive sheet and the like. In another embodiment, the total thickness of the non-adhesive layer may be 10 μm or more, or 20 μm or more (for example, 35 μm or more) from the viewpoint of light-shielding properties and handling properties.

< adhesive layer >

In the technique disclosed herein, the type of the adhesive constituting the adhesive layer is not particularly limited. The adhesive may contain 1 or 2 or more kinds of various rubbery polymers known in the adhesive field, such as acrylic polymers, rubber polymers, polyester polymers, urethane polymers, polyether polymers, silicone polymers, polyamide polymers, and fluorine polymers, as base polymers. From the viewpoint of adhesive properties, cost, and the like, an adhesive containing an acrylic polymer or a rubber-based polymer as a base polymer can be preferably used. Among them, a pressure-sensitive adhesive (acrylic pressure-sensitive adhesive) containing an acrylic polymer as a base polymer is preferable. Hereinafter, a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive, that is, an acrylic pressure-sensitive adhesive layer will be mainly described, but the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein is not intended to be limited to a pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive.

The "base polymer" of the binder means a main component of the rubbery polymer contained in the binder. The rubbery polymer is a polymer that exhibits rubber elasticity in a temperature range around room temperature. In the present specification, the term "main component" means a component contained in an amount exceeding 50% by weight unless otherwise specified.

In addition, "acrylic polymer" refers to a polymer containing, as a monomer unit constituting the polymer, a monomer unit derived from a monomer having at least one (meth) acryloyl group in 1 molecule. Hereinafter, a monomer having at least one (meth) acryloyl group in 1 molecule is also referred to as an "acrylic monomer". Accordingly, the acrylic polymer in the present specification is defined as a polymer comprising a monomer unit derived from an acrylic monomer. Typical examples of the acrylic polymer include acrylic polymers in which the proportion of the acrylic monomer in all monomer components used for the synthesis of the acrylic polymer is more than 50% by weight.

In addition, "(meth) acryloyl" means acryloyl and methacryloyl in a general sense. Similarly, "(meth) acrylate" means acrylate and methacrylate in general, and "(meth) acrylic acid" means acrylic acid and methacrylic acid in general.

As the acrylic polymer, for example, a polymer of a monomer raw material containing an alkyl (meth) acrylate as a main monomer and further containing a sub-monomer copolymerizable with the main monomer is preferable. Here, the main monomer means a component accounting for more than 50% by weight in the monomer composition of the above monomer raw materials.

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

CH₂＝C(R¹)COOR² (1)

Here, R in the above formula (1)¹Is a hydrogen atom or a methyl group. And, R²Is a chain alkyl group having 1 to 20 carbon atoms. Hereinafter, such a range of the number of carbon atoms may be represented by "C_1-20". From the viewpoint of storage modulus of the binder, etc., with R²Is C_1-14(e.g. C)_2-10Typically C_4-8) The alkyl (meth) acrylate of (a) a chain alkyl group is suitable as a main monomer. From the viewpoint of adhesive properties, R is preferably used¹Is a hydrogen atom and R²Is C_4-8Alkyl acrylate having a chain alkyl group (hereinafter also referred to simply as acrylic acid C)_4-8An alkyl ester. ) As the main monomer.

As R²Is C_1-20Examples of the alkyl (meth) acrylate of the chain alkyl group of (a) include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, Pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like. These alkyl (meth) acrylates may be used singly in 1 kind or in combination in 2 or more kinds. Preferred alkyl (meth) acrylates include n-Butyl Acrylate (BA) and 2-ethylhexyl acrylate (2 EHA).

The proportion of the alkyl (meth) acrylate in the total monomer components used for synthesizing 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 proportion of the alkyl (meth) acrylate is not particularly limited, and is usually preferably 99.5% by weight or less (for example, 99% by weight or less). Alternatively, the acrylic polymer may be one obtained by polymerizing substantially only the alkyl (meth) acrylate. In addition, propylene was usedAcid C_4-8When an alkyl ester is used as the monomer component, acrylic acid C is contained in the alkyl (meth) acrylate contained in the monomer component_4-8The proportion of the alkyl ester is preferably 70% by weight or more, more preferably 90% by weight or more, and still more preferably 95% by weight or more (typically 99 to 100% by weight). The technique disclosed herein can be preferably carried out in such a manner that 50% by weight or more (for example, 60% by weight or more, typically 70% by weight or more) of the total monomer components is BA. In a preferred embodiment, the total monomer component may further contain 2EHA in a proportion less than BA.

For the acrylic polymer in the technology disclosed herein, monomers (other monomers) other than the above may be copolymerized within a range not significantly impairing the effects of the present invention. The other monomer can be used for the purpose of, for example, adjusting the glass transition temperature (Tg) of the acrylic polymer, adjusting the adhesive properties (e.g., releasability), and the like. Examples of the monomer capable of improving the cohesive force and heat resistance of the adhesive include a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a cyano group-containing monomer, vinyl esters, and aromatic vinyl compounds. Among these, vinyl esters are suitable examples. Specific examples of the vinyl esters include vinyl acetate (VAc), vinyl propionate, and vinyl laurate. Among them, VAc is preferred.

Examples of the other monomer that can introduce a functional group that serves as a crosslinking base point into the acrylic polymer or can contribute to improvement of the adhesive strength include a hydroxyl group (OH group) -containing monomer, a carboxyl group-containing monomer, an acid anhydride group-containing monomer, an amide group-containing monomer, an amino group-containing monomer, an imide group-containing monomer, an epoxy group-containing monomer, (meth) acryloylmorpholine, vinyl ethers, and the like.

As one preferable example of the acrylic polymer in the technique disclosed herein, there is an acrylic polymer obtained by copolymerizing a carboxyl group-containing monomer 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, and the like. Among them, AA and MAA are preferable.

As another suitable example, there can be mentioned an acrylic polymer obtained by copolymerizing a hydroxyl group-containing monomer as the other monomer. Examples of the hydroxyl group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate; polypropylene glycol mono (meth) acrylate; n-hydroxyethyl (meth) acrylamide, and the like. Among these, preferable examples of the hydroxyl group-containing monomer include a linear hydroxyalkyl (meth) acrylate having an alkyl group of 2 to 4 carbon atoms.

The "other monomers" can be used singly or in combination of 2 or more. The total content of the other monomers is preferably about 40% by weight or less (typically 0.001 to 40% by weight) of the total monomer components, and more preferably about 30% by weight or less (typically 0.01 to 30% by weight, for example, 0.1 to 10% by weight).

When a carboxyl group-containing monomer is used as the other monomer, the content thereof is preferably about 0.1% by weight or more (for example, about 0.2% by weight or more, typically about 0.5% by weight or more) of the total monomer components, and is preferably about 10% by weight or less (for example, about 8% by weight or less, typically about 5% by weight or less). When a hydroxyl group-containing monomer is used as the other monomer, the content thereof is preferably about 0.001% by weight or more (e.g., about 0.01% by weight or more, typically about 0.02% by weight or more) of the total monomer components, and preferably about 10% by weight or less (e.g., about 5% by weight or less, typically about 2% by weight or less).

The copolymerization composition of the acrylic polymer is suitably designed so that the glass transition temperature (Tg) of the polymer is-15 ℃ or lower (typically-70 ℃ or higher and-15 ℃ or lower). The Tg of the acrylic polymer is preferably-25 ℃ or lower (for example, -60 ℃ or higher and-25 ℃ or lower), and more preferably-40 ℃ or lower (for example, -60 ℃ or higher and-40 ℃ or lower). It is preferable to set the Tg of the acrylic polymer to the upper limit or less from the viewpoint of workability of attaching the adhesive sheet.

The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (i.e., the kind of the monomer used for synthesis of the polymer, the amount ratio used). Here, Tg of the acrylic polymer is a value obtained from the Fox formula based on the composition of monomer components used for synthesizing the polymer. The formula Fox is a relational expression between Tg of the copolymer and glass transition temperature Tgi of a homopolymer obtained by homopolymerizing each monomer constituting the copolymer, as shown below.

1/Tg＝Σ(Wi/Tgi)

In the above Fox formula, Tg represents the glass transition temperature (unit: K) of the copolymer, Wi represents the weight fraction (copolymerization ratio on a weight basis) of the monomer i in the copolymer, and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i.

The glass transition temperature of the homopolymer used for calculation of Tg was the value described in the publicly known data. For example, for the monomers listed below, the following values are used as the glass transition temperatures of the homopolymers of the monomers.

For the glass transition temperature of the homopolymer other than those exemplified above, the value described in "Polymer Handbook" (3 rd edition, John Wiley & Sons, Inc.,1989) was used. The highest value is used for monomers having various values described in this document.

In the above-mentioned documents, when the glass transition temperature of the homopolymer is not described, the value obtained by the following measurement method is used.

Specifically, 100 parts by weight of a monomer, 0.2 parts by weight of 2, 2' -azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were put into a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, and stirred for 1 hour while introducing nitrogen. After the oxygen in the polymerization system was removed in this manner, the temperature was raised to 63 ℃ to carry out the reaction for 10 hours. Then, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content of 33% by weight. Subsequently, the homopolymer solution was cast on a release liner and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. The test sample was punched out into a disk shape having a diameter of 7.9mm, and sandwiched between parallel plates, while applying a shear strain having a frequency of 1Hz using a viscoelasticity tester (model name "ARES" manufactured by TA Instruments Japan Inc.) to measure viscoelasticity in a shear mode at a temperature rise rate of 5 ℃/min in a temperature range of-70 to 150 ℃, and the peak top temperature of tan δ was taken as Tg of the homopolymer.

The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as a method for synthesizing an acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, and a photopolymerization method, can be appropriately used. For example, solution polymerization can be preferably used. As a method of supplying the monomer in the case of performing the solution polymerization, a batch charging method, a continuous supply (dropwise) method, a batch supply (dropwise) method, or the like, in which all the monomer raw materials are supplied at once, can be suitably employed. The polymerization temperature may be appropriately selected depending on the kind of the monomer and the solvent used, the kind of the polymerization initiator, and the like, and may be, for example, about 20 ℃ or higher (typically about 40 ℃ or higher), or may be, for example, about 170 ℃ or lower (typically about 140 ℃ or lower). In a preferred embodiment, a polymerization temperature of about 75 ℃ or less (more preferably about 65 ℃ or less, for example, about 45 ℃ to 65 ℃) can be used.

The solvent (polymerization solvent) used in the solution polymerization may be appropriately selected from conventionally known organic solvents. For example, aromatic compounds (typically aromatic hydrocarbons) selected from toluene and the like; acetates such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1, 2-dichloroethane; lower alcohols (e.g., monohydric alcohols having 1 to 4 carbon atoms) such as isopropyl alcohol; ethers such as t-butyl methyl ether; any one solvent or a mixed solvent of 2 or more kinds of ketones such as methyl ethyl ketone.

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, 1 or 2 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 initiators such as phenyl-substituted ethane; aromatic carbonyl compounds, and the like. As another example of the polymerization initiator, a redox initiator composed of a combination of a peroxide and a reducing agent may be cited. Such polymerization initiators may be used in 1 kind alone or in combination of 2 or more kinds. The amount of the polymerization initiator to be used may be generally used, and may be selected from the range of about 0.005 to 1 part by weight (typically about 0.01 to 1 part by weight) based on 100 parts by weight of the total monomer components.

The solution polymerization described above can provide a polymerization reaction solution in which the acrylic polymer is dissolved in an organic solvent. The pressure-sensitive adhesive layer in the technique disclosed herein may be formed from a pressure-sensitive adhesive composition containing the above-mentioned polymerization reaction liquid or an acrylic polymer solution obtained by subjecting the reaction liquid to an appropriate post-treatment. As the acrylic polymer solution, a solution obtained by adjusting the polymerization reaction solution to an appropriate viscosity (concentration) as necessary can 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, or the like) and dissolving the acrylic polymer in an organic solvent may also be used.

The weight average molecular weight (Mw) of the base polymer (preferably, acrylic polymer) in the technology disclosed herein is not particularly limited, and may be, for example, 10 × 10⁴～500×10⁴The range of (1). From the viewpoint of adhesive properties, the Mw of the base polymer is preferably at 10X 10⁴Above (e.g., 20 × 10)⁴Above, typically 35 × 10⁴Above), and further, preferably in the range of 150 × 10⁴The following (e.g., 75X 10)⁴The followingTypically 65 x 10⁴Below). Here, Mw is a value in terms of standard polystyrene obtained by GPC (gel permeation chromatography). As the GPC apparatus, for example, the type name "HLC-8320 GPC" (column: TSKgelGMH-H (S), manufactured by Tosoh corporation) can be used.

The adhesive in the technology disclosed herein may be a composition comprising a tackifying resin. The tackifier resin is not particularly limited, and various tackifier resins such as rosin-based tackifier resin, terpene-based tackifier resin, hydrocarbon-based tackifier resin, epoxy-based tackifier resin, polyamide-based tackifier resin, elastic-based tackifier resin, phenol-based tackifier resin, and ketone-based tackifier resin can be used. These tackifier resins may be used singly in 1 kind or in combination in 2 or more kinds. When an acrylic polymer is used as the base polymer, a rosin-based tackifier resin is preferably used.

Examples of the rosin-based tackifying resin include unmodified rosins (raw rosins) such as gum rosin (gum rosin), wood rosin, and tall oil rosin; modified rosins obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, or the like (hydrogenated rosins, disproportionated rosins, polymerized rosins, and other chemically modified rosins, and the like); other various rosin derivatives, and the like. Examples of the rosin derivatives include: rosin esters such as those obtained by esterifying unmodified rosins with alcohols (i.e., esterified products of rosins) and those obtained by esterifying modified rosins with alcohols (i.e., esterified products of modified rosins); unsaturated fatty acid modified rosins obtained by modifying unmodified rosins and modified rosins with unsaturated fatty acids; unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing carboxyl groups in unmodified rosin, modified rosin, unsaturated fatty acid-modified rosin or unsaturated fatty acid-modified rosin ester; metal salts of rosins (particularly, rosin esters) such as unmodified rosins, modified rosins, and various rosin derivatives; rosin phenol resins obtained by polymerizing a rosin (such as an unmodified rosin, a modified rosin, and various rosin derivatives) with phenol in the presence of an acid catalyst and thermally polymerizing the resulting product, and the like.

The softening point (softening temperature) of the tackifier resin used is not particularly limited. For example, tackifying resins having a softening point of about 100 ℃ or higher (preferably about 120 ℃ or higher) can be used. A rosin-based tackifier resin (for example, an esterified product of a polymerized rosin) having such a softening point can be preferably used. The upper limit of the softening point of the tackifier resin is not particularly limited, and may be set to about 200 ℃ or lower (typically about 180 ℃ or lower, for example about 150 ℃ or lower). The softening point of the tackifier resin as referred to herein is defined as a value measured by a softening point test method (ring and ball method) specified in any one of JIS K5902 and JIS K2207.

The amount of the tackifier resin to be used is not particularly limited, and may be appropriately set in accordance with the target adhesive performance (peel strength, etc.). For example, the tackifier resin is preferably used 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) and preferably about 100 parts by weight or less (more preferably 80 parts by weight or less, and still more preferably 60 parts by weight or less) with respect to 100 parts by weight of the base polymer.

In the technique disclosed herein, the adhesive composition used for forming the adhesive layer may contain a crosslinking agent as needed. The kind of the crosslinking agent is not particularly limited, and can be appropriately selected from conventionally known crosslinking agents. Examples of such a crosslinking agent include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a melamine-based crosslinking agent, a peroxide-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a carbodiimide-based crosslinking agent, and an amine-based crosslinking agent. The crosslinking agent may be used alone in 1 kind or in combination of 2 or more kinds. Among these, from the viewpoint of improving the cohesive force, an isocyanate-based crosslinking agent and/or an epoxy-based crosslinking agent is preferably used, and an isocyanate-based crosslinking agent is particularly preferably used. The amount of the crosslinking agent used is not particularly limited. For example, the amount of the acrylic polymer is about 10 parts by weight or less, preferably about 0.005 to 10 parts by weight, more preferably about 0.01 to 5 parts by weight, based on 100 parts by weight of the base polymer (preferably, the acrylic polymer).

The adhesive layer in the technology disclosed herein may be colored in order to exhibit desired design properties and optical characteristics (e.g., light-shielding properties). This coloring may be performed by appropriately combining 1 or 2 or more kinds of known organic or inorganic coloring agents (pigments, dyes, etc.). For example, the pressure-sensitive adhesive layer can be colored black by including a black-based colorant such as carbon black in the pressure-sensitive adhesive layer. The content of the colorant is not particularly limited, and may be, for example, less than 15 parts by weight relative to 100 parts by weight of the base polymer. From the viewpoint of suppressing the decrease in the adhesive property, the content of the colorant is preferably set to about less than 10 parts by weight (for example, less than 5 parts by weight, and typically less than 3 parts by weight) relative to 100 parts by weight of the base polymer. The technique disclosed herein may be preferably carried out in such a manner that the adhesive layer does not substantially contain inorganic and organic colorants from the viewpoint of adhesive properties. For example, the colorant can be contained in an amount of preferably 0 to 1 part by weight based on 100 parts by weight of the base polymer.

The pressure-sensitive adhesive composition may contain, as required, various additives commonly used in the field of pressure-sensitive adhesive compositions such as leveling agents, crosslinking aids, plasticizers, softening agents, antistatic agents, antioxidants, ultraviolet absorbers, antioxidants, and light stabilizers. For such various additives, conventionally known additives can be used according to a conventional method, and since they are not particularly components that provide the features of the present invention, detailed descriptions thereof are omitted.

The pressure-sensitive adhesive layer (layer formed of a pressure-sensitive adhesive) disclosed herein may be a pressure-sensitive adhesive layer formed of a pressure-sensitive adhesive composition in various forms such as a water-based pressure-sensitive adhesive composition, a solvent-based pressure-sensitive adhesive composition, a hot-melt pressure-sensitive adhesive composition, an active energy ray-curable pressure-sensitive adhesive composition, or the like. The aqueous pressure-sensitive adhesive composition is a pressure-sensitive adhesive composition in a form containing a pressure-sensitive adhesive (pressure-sensitive adhesive layer-forming component) in a solvent (aqueous solvent) mainly containing water, and typically includes a pressure-sensitive adhesive composition called an aqueous dispersion type pressure-sensitive adhesive composition (a composition in which at least a part of the pressure-sensitive adhesive is dispersed in water) and the like. The solvent-based adhesive composition is an adhesive composition in which an adhesive is contained in an organic solvent. The technique disclosed herein can be preferably implemented to have an adhesive layer formed from a solvent-based adhesive composition, from the viewpoint of adhesive properties and the like.

The adhesive layer disclosed herein may be formed using a conventionally known method. For example, a method (direct method) of directly applying (typically, coating) a pressure-sensitive adhesive composition to the above-mentioned base film and drying the composition to form a pressure-sensitive adhesive layer can be employed. Further, a method (transfer method) may be employed in which a pressure-sensitive adhesive layer is formed on a surface (release surface) having releasability by applying a pressure-sensitive adhesive composition to the surface and drying the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is transferred to a base film. The transfer method is preferable from the viewpoint of productivity. The release surface may be the surface of a release liner, the back surface of a base film subjected to a release treatment, or the like. The pressure-sensitive adhesive layer disclosed herein is typically formed continuously, but is not limited to this form, and may be formed in a regular pattern such as dots or stripes, or a random pattern.

The application of the adhesive composition can be performed using a conventionally known coater such as a gravure coater, die coater, or bar coater. Alternatively, the adhesive composition may be applied by impregnation, curtain coating, or the like.

From the viewpoint of accelerating the crosslinking reaction, improving the production efficiency, and the like, the drying of the adhesive composition is preferably performed under heating. The drying temperature may be, for example, about 40 to 150 ℃, and is preferably about 60 to 130 ℃. After drying the pressure-sensitive adhesive composition, the curing may be further performed for the purpose of adjusting the transfer of components in the pressure-sensitive adhesive layer, advancing the crosslinking reaction, relaxing strains possibly existing in the substrate film and the pressure-sensitive adhesive layer, and the like.

The thickness of the adhesive layer disclosed herein is not particularly limited and may be appropriately selected according to the purpose. Generally, from the viewpoint of productivity such as drying efficiency, adhesion performance, and the like, about 1 μm or more (e.g., about 2 μm or more, typically about 4 μm or more) is suitable, and about 200 μm or less (e.g., about 140 μm or less, typically about 80 μm or less) is suitable. From the viewpoint of limiting the total thickness of the pressure-sensitive adhesive sheet, the thickness is preferably about 1 μm to 40 μm, and more preferably about 1.2 μm to 30 μm (for example, 20 μm or less, and typically 10 μm or less). The technique disclosed herein can also be implemented so that the thickness of the pressure-sensitive adhesive layer is 5 μm or less (further 3 μm or less). A pressure-sensitive adhesive layer having a small thickness is also advantageous in terms of reduction in thickness, size, weight, resource conservation, and the like of the pressure-sensitive adhesive sheet. In addition, when the adhesive sheet is applied to a graphite sheet, the adhesive layer is preferably thin from the viewpoint of heat dissipation efficiency.

< Release liner >

In the technique disclosed herein, a release liner may be used for the formation of the pressure-sensitive adhesive layer, the production of the pressure-sensitive adhesive sheet, the storage, distribution, shape processing, and the like of 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 material such as a resin film or paper, and a release liner made of a low-adhesive material such as a fluorine-based polymer (polytetrafluoroethylene or the like) or a polyolefin-based resin (polyethylene, polypropylene or the like). The release treatment layer may be formed by surface-treating the backing material with a release treatment agent such as silicone, long-alkyl, fluorine, or molybdenum sulfide. In the release liner used for the one-side adhesive pressure-sensitive adhesive sheet, typically, the surface that is in contact with the adhesive surface of the pressure-sensitive adhesive sheet is configured as a releasable surface (release-treated surface), and the other surface may be a non-release-treated surface. The thickness (total thickness) of the release liner is not particularly limited, and is preferably about 10 μm or more (e.g., about 15 μm or more), and preferably about 500 μm or less (e.g., about 100 μm or less), from the viewpoint of peeling workability, handling property, strength, and the like.

< use >)

The adhesive sheet disclosed herein can be preferably applied to portable electronic device applications. For example, the present invention can be preferably used for protection of members, design improvement, and the like, in a mobile phone, a smartphone, a tablet personal computer, a notebook personal computer, various wearable devices (e.g., a wrist-worn type worn on a wrist such as a wristwatch, a modular type worn on a part of the body with a clip, a band, and the like, an eye-worn (eyewear) type including a glasses type (a monocular type, a binocular type, and a helmet type), a clothing type attached to a shirt, a sock, a hat, and the like in the form of a decoration, an ear-worn type attached to an ear such as an earphone, and the like), a digital camera, a digital video camera, an audio device (a portable music player, a recording pen, and the like), a calculator (a desktop calculator, and the like), a portable game device, an electronic dictionary, an electronic organizer, an electronic book, a vehicle-mounted information device, a portable radio, a portable television, and the like, Portable electronic devices such as portable printers, portable scanners, portable modems, and the like. In the present specification, "portable" is not sufficient if it is interpreted as being merely portable, and means having a level of portability at which an individual (a standard adult) can be relatively easily carried.

In a preferred embodiment, the adhesive sheet disclosed herein is used by being adhered to a graphite sheet. A graphite sheet is preferably used in various small electronic devices as a heat sink for dissipating heat from a heat generating element (a battery, an IC chip, or the like). 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 and around the power generating element. Since such a graphite sheet has uneven appearance and is easily broken when the thickness is small, it is preferable to attach an adhesive sheet to the surface thereof for the purpose of improving appearance, protecting, and the like. By applying the adhesive sheet disclosed herein to a graphite sheet, improvement in appearance quality is preferably achieved. Further, since the pressure-sensitive adhesive sheet having a predetermined color tone (low brightness, chroma) and a gloss value on the back surface thereof can exhibit a black color with a rich sense of thickness with suppressed gloss, it can be harmonized with the color tone of the graphite sheet and the surrounding members. Further, when a pressure-sensitive adhesive sheet having a light transmittance within a predetermined range is used, the color tone of the graphite sheet can be reflected appropriately on the outer surface, and desired color tone, texture, and design properties can be provided. Although not particularly limited, the adhesive sheet disclosed herein is preferably applied to a graphite sheet having a thickness of 4 to 100 μm and/or an arithmetic average surface roughness Ra of 0.005 to 5 μm.

In another preferred embodiment, the adhesive sheet disclosed herein is used by being attached to a ferrite sheet. Ferrite sheets are preferably used in various electronic devices as magnetic sheets that absorb electromagnetic waves emitted from electronic devices or the like or that absorb electromagnetic waves that intrude into electronic devices or the like, for example. For example, the ferrite sheet is disposed in the electronic device at a position close to an antenna coil in an RFID (Radio Frequency Identification) tag, specifically, between the antenna coil and a conductive member. Since such ferrite sheets are brittle and easily broken when they are thin, it is preferable to attach an adhesive sheet to the surface thereof for the purpose of protection and the like. By applying the adhesive sheet disclosed herein to a ferrite sheet, the ferrite sheet is well protected, preferably achieving an improvement in appearance quality. Further, since the pressure-sensitive adhesive sheet having a predetermined color tone (low brightness, chroma) and a gloss value on the back surface thereof can exhibit a black color with a full-bodied feel with suppressed gloss, it can be harmonized with the color tone of the ferrite sheet and the surrounding members. Further, when a pressure-sensitive adhesive sheet having a light transmittance within a predetermined range is used, the color tone of the ferrite sheet can be reflected appropriately on the outer surface, and desired color tone, texture, and design properties can be provided.

The matters disclosed in the present specification include the following technical means.

(1) A pressure-sensitive adhesive sheet having one-sided adhesiveness, which comprises a base film, a pressure-sensitive adhesive layer provided on a first surface of the base film, and a colored layer provided on a second surface of the base film,

the back surface of the adhesive sheet is a matte-treated surface having alcohol resistance.

(2) The adhesive sheet according to the item (1), wherein an alcohol-resistant layer is provided on the surface of the colored layer.

(3) The adhesive sheet according to the item (2), wherein the alcohol-resistant layer contains a particulate matting material.

(4) The adhesive sheet according to the above (2) or (3), wherein the alcohol-resistant layer has a thickness of 2 μm or less.

(5) The adhesive sheet according to any one of the above (1) to (4), wherein the 60 ° gloss value of the back surface of the adhesive sheet is 10 or less.

(6) The adhesive sheet according to any one of the above (1) to (5), wherein the adhesive sheet has a back surface with a luminance L defined by the color system la a b^*Is 40 or less.

(7) A release-liner-equipped adhesive sheet comprising the adhesive sheet according to any one of (1) to (6) above and a release liner for protecting the adhesive surface of the adhesive sheet.

(8) A pressure-sensitive adhesive sheet with a release liner, which comprises a pressure-sensitive adhesive sheet having single-sided adhesiveness and a release liner for protecting the adhesive surface of the pressure-sensitive adhesive sheet,

the adhesive sheet comprises a base film, an adhesive layer provided on a first surface of the base film, and a colored layer formed on a second surface of the base film,

the back surface of the adhesive sheet is a matte finish surface.

(9) The adhesive sheet according to any one of the above (1) to (8), wherein the total thickness of the adhesive sheet is 30 μm or less.

(10) The adhesive sheet according to any one of the above (1) to (9), which is used by being attached to a graphite sheet.

(11) The adhesive sheet according to any one of the above (1) to (10), wherein the adhesive layer contains an acrylic polymer at a ratio of more than 50% by weight of a polymer component contained in the adhesive layer,

the acrylic polymer contains an alkyl (meth) acrylate represented by formula (1) as a monomer component at a ratio of 70 wt% or more:

CH₂＝C(R¹)COOR² (1)

(R in the above formula (1))¹Is a hydrogen atom or a methyl group. And, R²Is a chain alkyl group having 1 to 20 carbon atoms. ).

(12) The adhesive sheet according to the item (11), wherein the alkyl (meth) acrylate is selected from the group consisting of methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, At least 1 member selected from the group consisting of tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, and eicosyl (meth) acrylate.

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

(14) The adhesive sheet according to any one of the above (11) to (13), wherein the alkyl (meth) acrylate is n-butyl acrylate and 2-ethylhexyl acrylate, and the 2-ethylhexyl acrylate is contained in the monomer component in a proportion smaller than that of the n-butyl acrylate.

(15) The adhesive sheet according to any one of the above (11) to (14), wherein the acrylic polymer further contains a functional group-containing monomer as the monomer component,

the functional group-containing monomer is at least 1 selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

(16) The adhesive sheet according to any one of the above (1) to (15), wherein the adhesive layer contains a rosin-based tackifier resin having a softening point of 100 ℃ or higher and 180 ℃ or lower as the tackifier resin,

the content of the tackifier resin is 20 to 60 parts by weight relative to 100 parts by weight of the base polymer of the adhesive layer.

(17) The adhesive sheet according to any one of the above (1) to (16), wherein the base film is a polyethylene terephthalate resin film.

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

(19) The adhesive sheet according to any one of the above (1) to (18), wherein the total thickness of the layers other than the adhesive layer is 5 μm or less.

(20) The adhesive sheet according to any one of the above (1) to (9), which is used by being attached to a ferrite sheet.

(21) An adhesive sheet, which is a single-sided adhesive sheet used by being adhered to a graphite sheet,

the adhesive sheet comprises a base film, an adhesive layer provided on a first surface of the base film, and a colored layer provided on a second surface of the base film,

the back surface of the adhesive sheet is a matte finish surface having alcohol resistance,

an alcohol-resistant layer is provided on the surface of the colored layer,

the alcohol-resistant layer contains a particulate matting material,

the alcohol-resistant layer has a thickness of 2 μm or less,

the 60 DEG gloss value of the back surface of the adhesive sheet is 10 or less,

brightness L defined by L a b chromaticity system on the back surface of the adhesive sheet^*The content of the organic acid is below 40%,

the total thickness of the adhesive sheet is 30 μm or less,

the adhesive layer contains an acrylic polymer in a proportion of more than 50% by weight of a polymer component contained in the adhesive layer,

the acrylic polymer contains an alkyl (meth) acrylate as a monomer component at a ratio of 70 wt% or more,

the aforementioned alkyl (meth) acrylate is n-butyl acrylate and 2-ethylhexyl acrylate, 2-ethylhexyl acrylate is contained in the aforementioned monomer components in a proportion smaller than that of n-butyl acrylate,

the aforementioned acrylic polymer further contains a functional group-containing monomer as the aforementioned monomer component,

the functional group-containing monomer is at least 1 selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate,

the adhesive layer contains a rosin-based tackifying resin having a softening point of 100 ℃ to 180 ℃ as a tackifying 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 adhesive layer,

the base film is a polyethylene terephthalate resin film,

the colored layer contains carbon black as a black pigment,

the total thickness of the layers other than the adhesive layer is 5 μm or less.

Examples

The following describes several embodiments related to the present invention, but the present invention is not intended to be limited to these embodiments. In the following description, "part" and "%" are based on weight unless otherwise specified.

< example 1 >

A reaction vessel equipped with a stirrer, a thermometer, a nitrogen inlet, a reflux condenser and a dropping funnel was charged with 70 parts of BA, 2EHA27 parts of AA3 parts of monomer components, 0.05 part of 4-hydroxybutyl acrylate and 135 parts of toluene as a polymerization solvent, and stirred for 2 hours while introducing nitrogen. After removing oxygen from the polymerization system in this manner, 0.1 part of AIBN as a polymerization initiator was added and solution polymerization was carried out at 60 ℃ for 6 hours to obtain a toluene solution of an acrylic polymer. The acrylic polymer has a Mw of about 40X 10⁴。

An acrylic pressure-sensitive adhesive composition was prepared by adding 30 parts of polymerized rosin ester (trade name "Pensel D-125", softening point 120-130 ℃, manufactured by Mitsuwa chemical industries, Ltd.) as a tackifier resin and 2 parts of an isocyanate-based crosslinking agent (trade name "CORONATE L", Toso Cao Co., Ltd., solid content 75%) to 100 parts of the acrylic polymer contained in the toluene solution.

As the release liner, a polyester release film (trade name "Diafil MRF", thickness 38 μm, manufactured by Mitsubishi polyester Co., Ltd.) having one side thereof subjected to a release treatment to become a release surface was prepared. The pressure-sensitive adhesive composition was applied to the release surface of a release liner so that the thickness after drying became 2 μm, and dried at 100 ℃ for 2 minutes. In this manner, the pressure-sensitive adhesive layer is formed on the release surface of the release liner.

Next, a black printed layer having a thickness of about 1 μm was formed on one side (second side) of a transparent PET film (product name "Mylar", manufactured by Teijin DuPont Films Japan Limited) having a thickness of 2 μm, and then a top coat having a thickness of about 1 μm was formed on the black printed layer, thereby preparing a PET film (a base film having a top coat formed thereon) having a black printed layer formed thereon. The top coat layer is formed by applying a mixture of an alcohol-resistant resin composition and a matting material to the surface of a black print layer, and both the black print layer and the top coat layer are formed using materials commercially available from daidzein co.

The pressure-sensitive adhesive layer formed on the release liner was adhered to the PET film side surface (first surface of the PET film layer) of the base film on which the top coat layer was formed, to prepare the pressure-sensitive adhesive sheet of this example (transfer method). The release liner remains directly on the pressure-sensitive adhesive layer and protects the surface (bonding surface) of the pressure-sensitive adhesive layer.

< example 2 >

The adhesive sheet of this example was produced in the same manner as in example 1 except that the composition of the black printing layer (e.g., change in the kind of resin) and the composition of the top coat layer (specifically, the amount of matting material used) were changed to change the gloss and color tone of the back surface of the adhesive sheet.

< example 3 >

The adhesive sheet of this example was produced in the same manner as in example 1 except that the composition of the black printing layer (change in the kind of resin, reduction in the amount of black pigment, etc.) was changed so as to change the gloss and color tone of the back surface of the adhesive sheet, and a top coat layer-forming composition containing the matte material in a commercially available transparent ink composition having no alcohol resistance was used.

< example 4 >

The adhesive sheet of this example was produced in the same manner as in example 1 except that the PET film having the black printing layer formed thereon without forming the top coat layer was used.

< example 5 >

The same composition as that used in example 1 for forming a top coat layer was prepared except that the matting material was not contained, and a top coat layer containing no matting material was formed on the black print layer surface of the PET film having the black print layer formed thereon using the composition containing no matting material. Except for this, a pressure-sensitive adhesive sheet of this example was produced in the same manner as in example 1.

< example 6 >

A pressure-sensitive adhesive layer was formed on the release surface of the release liner in the same manner as in example 1 except that the pressure-sensitive adhesive layer was formed so that the thickness after drying was 21 μm.

Then, a black printed layer having a thickness of about 5 μm was formed on one side (second side) of a transparent PET film having a thickness of 38 μm (trade name "Lumirror", manufactured by Toray Industries, inc.), and a top coat having a thickness of about 1 μm was formed on the black printed layer, thereby preparing a PET film having a black printed layer formed thereon (a base film having a top coat formed thereon). The top coat layer is formed by applying a mixture of an alcohol-resistant resin composition and a matting material to the surface of a black print layer, and both the black print layer and the top coat layer are formed using materials commercially available from daidzein co.

The pressure-sensitive adhesive layer formed on the release liner was adhered to the PET film side surface (first surface of the PET film layer) of the base film on which the top coat layer was formed in the same manner as in example 1 to prepare a pressure-sensitive adhesive sheet of this example (transfer method). The release liner remains directly on the pressure-sensitive adhesive layer and protects the surface (bonding surface) of the pressure-sensitive adhesive layer.

[ evaluation ]

For the adhesive sheets of the respective examples, the 60 ° gloss value of the back surface and the luminance L of the back surface were measured^*Chroma a^*And chroma b^*Light transmittance (%), 180-degree peel strength (N/20 mm). The results are shown in Table 1.

[ evaluation test for alcohol resistance ]

After the adhesive sheets of the respective examples prepared above were allowed to stand for 7 days, waste cloths (trade name "Savina Minimax", 50mm × 50mm KB SEIREN, manufactured by ltd.) containing 20mL of ethanol were prepared, and the back surfaces of the adhesive sheets were rubbed 2 or 3 times with a little force at positions sufficiently impregnated with the waste cloths. Then, the presence or absence of appearance change on the back surface of the pressure-sensitive adhesive sheet was visually observed. The case where no appearance change was observed was judged as "good", and the case where an appearance change (peeling, dissolution, or the like of the colored layer) was observed was judged as "bad". The results are shown in Table 1.

[ evaluation of appearance after alcohol addition ]

Ethanol was adhered to the back surface of each adhesive sheet and dried. With respect to example 5 in which the matte treatment was not performed, the case where the drying trace of ethanol was less visible than that in example 5 was evaluated as "o", and the case where the drying trace of ethanol was equally visible or easily visible was evaluated as "x". The results are shown in Table 1.

[ evaluation of interlayer peeling ]

The release liner-equipped adhesive sheets of the respective examples were unwound from a roll and evaluated for the presence or absence of interlayer peeling. The back surface of the pressure-sensitive adhesive sheet after unwinding was visually observed, and the case where no change was observed was evaluated as "o", and the case where a change was observed (for example, the case where a part of the back surface of the pressure-sensitive adhesive sheet was peeled off) was evaluated as "x". The results are shown in Table 1.

[ Table 1]

TABLE 1

As shown in table 1, the adhesive sheets of examples 1,2 and 6, which had alcohol resistance on the back surface and were matte-treated surfaces, had better appearance after alcohol addition than example 5, which had alcohol resistance but had a 60 ° gloss value of more than 90. Further, it was confirmed that example 4 in which no top coat was provided and example 3 in which a top coat having no alcohol resistance was formed were not alcohol-resistant, and therefore were not suitable for cleaning with alcohol. From these results, it is understood that the use of an adhesive sheet having alcohol resistance on the back surface and a matte-treated surface improves the appearance quality.

As shown in table 1, the adhesive sheets of examples 1,2 and 6, in which the back surface was made to be a matte finish surface, did not cause interlayer failure between the base material film and the colored layer, while the adhesive sheet of example 4, in which the 60 ° gloss value of the back surface was high, caused interlayer failure. As is clear from a comparison of these examples, in the adhesive sheet having the colored layer formed on the second surface of the base film, interlayer fracture can be prevented by forming the back surface of the adhesive sheet as a matte finish surface.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the scope of protection of the patent. The techniques described in the claims include various modifications and changes to the specific examples illustrated above.

Claims (14)

1. A release liner-equipped adhesive sheet used by being stuck to a graphite sheet or ferrite sheet, comprising an adhesive sheet and a release liner for protecting the adhesive surface of the adhesive sheet, wherein the adhesive sheet is a one-sided adhesive sheet comprising a base film, an adhesive layer provided on a first surface of the base film, and a colored layer provided on a second surface of the base film,

the adhesive layer contains an acrylic polymer in a proportion of more than 50% by weight of a polymer component contained in the adhesive layer,

the acrylic polymer contains an alkyl (meth) acrylate represented by the formula (1) as a monomer component at a ratio of 70 wt% or more,

CH₂＝C(R¹)COOR² (1)

r in the formula (1)¹Is a hydrogen atom or a methyl group, and, R²Is a chain alkyl group having 1 to 20 carbon atoms,

the back surface of the adhesive sheet is a matte finish surface having alcohol resistance,

the 60 DEG gloss value of the back surface of the adhesive sheet is 8.3 or less,

when the release-lined adhesive sheet is produced in a roll form, the outer surface of the release liner is in contact with the back surface of the adhesive sheet.

2. The release liner-equipped adhesive sheet according to claim 1, wherein an alcohol-resistant layer is provided on the surface of the colored layer.

3. The release liner-attached adhesive sheet according to claim 2, wherein the alcohol-resistant layer contains a particulate matting material.

4. The release liner-attached adhesive sheet according to claim 2 or 3, wherein the alcohol-resistant layer has a thickness of 2 μm or less.

5. The release-liner-attached adhesive sheet according to claim 1 or 2, wherein the adhesive sheet has a brightness L defined by the L a b color system on the back surface thereof^*Is 40 or less.

6. The release-liner-attached adhesive sheet according to claim 1 or 2, wherein the total thickness of the adhesive sheet is 30 μm or less.

7. The release-liner-attached adhesive sheet according to claim 1, wherein the alkyl (meth) acrylate is n-butyl acrylate and 2-ethylhexyl acrylate.

8. The release-liner-attached adhesive sheet according to claim 7, wherein 2-ethylhexyl acrylate is contained in the monomer component in a proportion smaller than n-butyl acrylate.

9. The release-liner-attached adhesive sheet according to claim 7 or 8, wherein the acrylic polymer further contains a functional group-containing monomer as the monomer component,

the functional group-containing monomer is at least 1 selected from the group consisting of acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate.

10. The release liner-attached adhesive sheet according to claim 7 or 8, wherein the adhesive layer contains, as a tackifier resin, a rosin-based tackifier resin having a softening point of 100 ℃ or higher and 180 ℃ or lower,

the content of the tackifying resin is 20 to 60 parts by weight relative to 100 parts by weight of the base polymer of the adhesive layer.

11. The release-liner-attached adhesive sheet according to claim 1 or 2, wherein the base film is a polyethylene terephthalate resin film.

12. The release-liner-attached adhesive sheet according to claim 1 or 2, wherein the colored layer contains carbon black as a black pigment.

13. The release liner-attached adhesive sheet according to claim 1 or 2, wherein the total thickness of layers other than the adhesive layer in the adhesive sheet is 5 μm or less.

14. A release liner-equipped adhesive sheet used by being adhered to a graphite sheet or ferrite sheet, comprising an adhesive sheet having one-side adhesiveness and a release liner for protecting the adhesive surface of the adhesive sheet,

the adhesive sheet comprises a base film, an adhesive layer provided on a first surface of the base film, and a colored layer formed on a second surface of the base film,

the adhesive layer contains an acrylic polymer in a proportion of more than 50% by weight of a polymer component contained in the adhesive layer,

the acrylic polymer contains an alkyl (meth) acrylate represented by the formula (1) as a monomer component at a ratio of 70 wt% or more,

CH₂＝C(R¹)COOR² (1)

r in the formula (1)¹Is a hydrogen atom or a methyl group, and, R²Is a chain alkyl group having 1 to 20 carbon atoms,

the back surface of the adhesive sheet is a matte finish surface,

the 60 DEG gloss value of the back surface of the adhesive sheet is 8.3 or less,

when the release-lined adhesive sheet is produced in a roll form, the outer surface of the release liner is in contact with the back surface of the adhesive sheet.

Images