JP6774806B2 - Adhesive sheet - Google Patents

Description

The present invention relates to an adhesive sheet. More specifically, the present invention relates to an adhesive sheet suitable for joining a liquid crystal display module unit and a backlight unit in a liquid crystal display device built in a portable electronic device, for example.

In general, a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive; the same applies hereinafter) exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature, and has a property of easily adhering to an adherend by pressure. Taking advantage of such properties, the adhesive is widely used, for example, in the form of an adhesive sheet with a base material for the purpose of joining, fixing, and protecting members in a portable electronic device such as a mobile phone. For example, in a liquid crystal display device built into a portable electronic device such as a mobile phone, a liquid crystal display module unit (hereinafter, also referred to as “LCD unit”) and a backlight unit (hereinafter, also referred to as “BL unit”) are joined. For the purpose, the adhesive sheet with a base material as described above is used. Patent Documents 1 to 3 are mentioned as documents relating to this kind of technique.

JP-A-2002-235053 JP-A-2007-284551 JP-A-2009-197124

If the light from the BL unit passes through the adhesive sheet and leaks, the light may reduce the visibility of the liquid crystal display surface. In order to prevent this, for example, a light-absorbing colored layer (typically a black layer) is provided on the LCD unit side surface of the base material constituting the adhesive sheet, so that the adhesive sheet is provided from the BL unit side to the LCD unit side. It is designed to block the light transmitted through the LCD.

From the viewpoint of thinning the portable electronic device, the adhesive sheet used for joining the LCD unit and the BL unit has also been required to be thin (Patent Document 3 and the like). On the other hand, in recent years, there has been a tendency for mobile electronic devices to have a larger screen (wider display screen area) and more emphasis on design, in order to suppress a decrease in portability and improve design flexibility due to the larger screen. In addition, it has become desirable to reduce the width of the adhesive sheet. In response to such new needs, it is difficult for a thin adhesive sheet to achieve both narrowing and joining reliability. For example, since the pressure-sensitive adhesive is a viscoelastic body, it can contribute to shock absorption, but the pressure-sensitive adhesive layer tends to be thin in a thin pressure-sensitive adhesive sheet, and the shock-absorbing ability is further reduced by narrowing the width. For this reason, a thin and narrow adhesive sheet tends to lack impact resistance (performance of withstanding an impact such as a drop impact and maintaining a bond). Since the large-screen LCD unit is heavy, it is particularly difficult to achieve both narrowing and impact resistance.

The present inventor has studied thickening the pressure-sensitive adhesive layer in order to realize a pressure-sensitive adhesive that achieves both narrowing and impact resistance at a higher level. However, when the pressure-sensitive adhesive layer is made thicker than a certain level in the pressure-sensitive adhesive sheet shape having a narrow width (for example, about 0.6 mm or less) different from the previous one, the light of the BL unit is transmitted through the pressure-sensitive adhesive layer in the width direction. It has been found that a new problem arises in which the light leaks from the end face (penetrates) and causes uneven brightness on the liquid crystal display surface. It is considered that the background to this is that the performance of the backlight has improved dramatically in recent years, and the brightness of the light emitted from the backlight has improved accordingly.

Therefore, an object of the present invention is to provide an adhesive sheet having good impact resistance and suppressing light leakage from an end face having a narrow width.

The pressure-sensitive adhesive sheet provided by this specification includes a base film and a pressure-sensitive adhesive layer arranged on at least one surface of the base film. The pressure-sensitive adhesive layer typically contains a colorant in the pressure-sensitive adhesive layer. Further, the pressure-sensitive adhesive layer has a thickness of more than 25 μm and a light transmittance of 5% or less at a length of 0.6 mm. Since the pressure-sensitive adhesive sheet configured in this way has a pressure-sensitive adhesive layer thicker than 25 μm, it is suitable for both narrowing and impact resistance. Further, since the light transmittance of the pressure-sensitive adhesive layer at a length of 0.6 mm is limited to 5% or less, the pressure-sensitive adhesive layer having a thickness advantageous for improving impact resistance is narrowed and widthwise. It is possible to preferably achieve both suppression of light leakage to.

Here, in the present specification, the "light transmittance at a length of A mm" means the light transmittance measured for a sample having an optical path length of A mm. Hereinafter, the light transmittance at a length of A mm may be referred to as "Amm light transmittance". A specific method for measuring the Amm light transmittance will be described later. Further, in the following, preventing or suppressing an event in which light is transmitted (penetrated) in the width direction of the pressure-sensitive adhesive sheet and transmitted light leaks from an end face of the width may be referred to as "horizontal shading".

The pressure-sensitive adhesive sheet disclosed herein can be preferably carried out in an embodiment in which the 0.6 mm light transmittance of the layers constituting the pressure-sensitive adhesive sheet having a thickness of more than 25 μm is 5% or less. According to such an aspect, light leakage in the width direction of the pressure-sensitive adhesive sheet can be better suppressed. That is, an adhesive sheet having more excellent horizontal light-shielding property can be realized.

In the pressure-sensitive adhesive sheet according to a preferred embodiment, the total thickness of the pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet is more than 50% of the total thickness of the pressure-sensitive adhesive sheet. With such a configuration, it is possible to realize an adhesive sheet exhibiting a higher level of impact resistance.

The pressure-sensitive adhesive sheet disclosed herein preferably has a vertical light transmittance of 1% or less. According to such an adhesive sheet, vertical shading and horizontal shading can be suitably realized by one member.

The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in an embodiment in which the vertical light transmittance of the pressure-sensitive adhesive layer is higher than 25%. Such an aspect is advantageous from the viewpoint of improving the aesthetic appearance of the adhesive sheet. For example, it is possible to prevent poor dispersion due to excessive use of the colorant.

The pressure-sensitive adhesive sheet disclosed herein can be preferably implemented in a shape having at least a narrow portion. The width of the narrow portion is typically less than 2.0 mm, preferably less than 1.0 mm. An adhesive sheet having such a shape tends to leak light in the width direction in the narrow portion, and the narrow portion tends to be a starting point of peeling (bonding failure) due to an impact. Therefore, it is particularly meaningful to apply the technique disclosed herein to preferably achieve both impact resistance and horizontal light-shielding property even in a narrow portion.

The pressure-sensitive adhesive sheet disclosed herein can be preferably carried out in such a manner that the width of the pressure-sensitive adhesive layer in the narrow portion is 50 times or less the thickness of the pressure-sensitive adhesive layer. The larger the ratio of the thickness to the width of the pressure-sensitive adhesive layer, the more light is transmitted across the width of the pressure-sensitive adhesive layer constituting the narrow portion diagonally from bottom to top, with the light source side facing downward. , Inconveniences such as uneven brightness tend to occur. Therefore, it is particularly meaningful to apply the techniques disclosed herein to preferably achieve both impact resistance and horizontal light shielding property.

The pressure-sensitive adhesive sheet according to a preferred embodiment is a double-sided pressure-sensitive adhesive comprising a first pressure-sensitive adhesive layer arranged on one surface of the base film and a second pressure-sensitive adhesive layer arranged on the other surface of the base film. It is configured as a sheet. The thickness of both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is preferably larger than 25 μm. An adhesive sheet having such a structure is highly useful as a joining member and tends to have good impact resistance even in a narrow width. Both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer preferably have a light transmittance of 0.6 mm of 5% or less. An adhesive sheet having such a structure tends to have good horizontal light-shielding property and good impact resistance even in a narrow width.

The adhesive sheet disclosed herein makes use of the feature that impact resistance and horizontal light-shielding property can be suitably compatible even in a narrow width, for example, in a liquid crystal display device including an LCD unit and a BL unit. Can be suitably used for bonding with the BL unit.

It is sectional drawing which shows one structural example of the adhesive sheet schematically. It is sectional drawing which shows the other structural example of the adhesive sheet schematically.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for the implementation of the present invention are based on the teachings regarding the implementation of the invention described in the present specification and the common general knowledge at the time of filing. Can be understood by those skilled in the art. The present invention can be carried out based on the contents disclosed in the present specification and common general technical knowledge in the art. Further, in the following drawings, members / parts having the same action may be described with the same reference numerals, and duplicate description may be omitted or simplified. In addition, the embodiments described in the drawings are modeled for clearly explaining the present invention, and do not necessarily accurately represent the size and scale of the adhesive sheet of the present invention actually provided as a product. ..

As described above, the term "adhesive" as used herein refers to a material that exhibits a soft solid state (viscoelastic body) in a temperature range near room temperature and has the property of easily adhering to an adherend by pressure. .. The adhesive referred to here is generally a complex tensile modulus E ^* (1 Hz) as defined in "CA Dahlquist," Adhesion: Fundamental and Practice ", McLaren & Sons, (1966) P. 143". <material having a property that meets the ¹⁰ 7 dyne / cm ² (typically, a material having the properties in 25 ° C.) may be.

The pressure-sensitive adhesive sheet disclosed herein is a pressure-sensitive adhesive sheet with a base material having a pressure-sensitive adhesive layer on at least one surface of the base material film (support). The concept of an adhesive sheet as used herein may include what is called an adhesive tape, an adhesive label, an adhesive film, or the like. The pressure-sensitive adhesive sheet disclosed herein may be in the form of a roll or in the form of a single leaf. Alternatively, it may be an adhesive sheet in a form further processed into various shapes.

The pressure-sensitive adhesive sheet disclosed herein may have, for example, the cross-sectional structure schematically shown in FIG. The pressure-sensitive adhesive sheet 1 shown in FIG. 1 comprises a base film 10 and a first pressure-sensitive adhesive layer 21 and a second pressure-sensitive adhesive layer 22 supported on the first surface 10A and the second surface 10B of the base film 10, respectively. Be prepared. Both the first surface 10A and the second surface 10B are non-peeling surfaces (non-peeling surfaces). The pressure-sensitive adhesive sheet 1 is used by attaching the surface (first adhesive surface) 21A of the first pressure-sensitive adhesive layer 21 and the surface (second adhesive surface) 22A of the second pressure-sensitive adhesive layer 22 to the adherend, respectively. That is, the adhesive sheet 1 is configured as a double-sided adhesive sheet (double-sided adhesive adhesive sheet). The pressure-sensitive adhesive sheet 1 before use was protected by release liners 31 and 32 in which the first pressure-sensitive adhesive surface 21A and the second pressure-sensitive adhesive surface 22A were at least a surface (peeling surface) having peelability on the pressure-sensitive adhesive surface side. It has a configuration. Alternatively, the release liner 32 is omitted, and a release liner 31 having both sides as release surfaces is used, and the adhesive sheet 1 is wound so that the second adhesive surface 22A comes into contact with the back surface of the release liner 31. Therefore, the second adhesive surface 22A may also be configured to be protected by the release liner 31.

At least one of the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 is a pressure-sensitive adhesive layer having a thickness of more than 25 μm and a light transmittance of 0.6 mm or less of 5% or less, and is contained in the pressure-sensitive adhesive layer. Contains a colorant. Both the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 have a thickness of more than 25 μm and a light transmittance of 0.6 mm of 5% or less, and the pressure-sensitive adhesive layer contains a colorant. It may be an agent layer. As the colorant, for example, a black colorant can be preferably adopted.

The pressure-sensitive adhesive sheet 1 preferably has a vertical light transmittance of 1% or less. A colorant may be dispersed (kneaded) in the base film 10 (preferably a resin film) for the purpose of adjusting the vertical light transmittance and the reflectance of the pressure-sensitive adhesive sheet 1. As the colorant, a black colorant or a white colorant can be preferably adopted.

Further, the base film may be colored by a colored layer arranged on the surface of the base film (preferably a resin film). FIG. 2 shows an example of the configuration of the pressure-sensitive adhesive sheet provided with such a base film. The base film 10 of the pressure-sensitive adhesive sheet 2 includes a resin film 12 as a base film and a colored layer 14 provided on one surface of the base film. The colored layer 14 may be, for example, a black printed layer printed on the surface of the resin film 12. Other configurations are the same as those of the adhesive sheet 1 shown in FIG. The resin film 12 may be transparent or may have a colorant dispersed therein. Further, the colored layer may be provided only on one surface of the base film as shown in FIG. 2, and the same or different colored layers are provided on one surface and the other surface of the base film, respectively. You may.

The pressure-sensitive adhesive sheet disclosed herein may be in the form of a single-sided pressure-sensitive adhesive sheet having an pressure-sensitive adhesive layer on only one side of the base film. As an example of the form of the single-sided adhesive sheet, the configuration shown in FIG. 1 does not have either the first adhesive layer 21 or the second adhesive layer 22, or the configuration shown in FIG. 2 has the first adhesive layer 21. And a form having no one of the second pressure-sensitive adhesive layers 22 can be mentioned.

<Adhesive layer>
The pressure-sensitive adhesive sheet disclosed herein has a pressure-sensitive adhesive layer thicker than 25 μm on at least one surface of the base film. The pressure-sensitive adhesive sheet configured in this way tends to exhibit good impact resistance even in a narrow width. From the viewpoint of obtaining higher impact resistance, the thickness of the pressure-sensitive adhesive layer can be, for example, 27 μm or more, 30 μm or more, or 35 μm or more. The upper limit of the thickness of the pressure-sensitive adhesive layer is not particularly limited. From the viewpoint of ease of processing when preparing the pressure-sensitive adhesive sheet into a narrow shape (a shape including at least a narrow portion), the thickness of the pressure-sensitive adhesive layer is usually 100 μm or less, and is 75 μm. The following is preferable, and 60 μm or less (for example, 50 μm or less) is preferable.

The pressure-sensitive adhesive layer thicker than 25 μm preferably has a 0.6 mm light transmittance of 5% or less. This makes it possible to achieve both narrowing and horizontal shading. Here, the 0.6 mm light transmittance can be grasped by preparing a sheet-shaped measurement sample having a thickness of 0.6 mm and measuring the light transmittance in the thickness direction of the measurement sample. The light transmittance is measured by irradiating one surface of the measurement sample with light having a wavelength of 380 to 780 nm perpendicularly to one surface of the measurement sample and measuring the intensity of the light transmitted through the other surface using a commercially available spectrophotometer. Desired. As the spectrophotometer, for example, a spectrophotometer manufactured by Hitachi, Ltd. (device name "U4100 type spectrophotometer") can be used. The same applies to the examples described later.

The 0.6 mm light transmittance of the pressure-sensitive adhesive layer is measured using a sheet-shaped pressure-sensitive adhesive having a thickness of 0.6 mm as a measurement sample. In the measurement sample, for example, a container having a flat peelable bottom surface is held horizontally, the pressure-sensitive adhesive composition is poured into the container, and the pressure-sensitive adhesive composition is slowly dried or cured to adhere to the bottom surface with a thickness of 0.6 mm. It can be prepared by forming a drug layer. Alternatively, by applying the pressure-sensitive adhesive composition on the peel-off surface of the release liner and drying it, a pressure-sensitive adhesive layer having an appropriate thickness (for example, about 0.05 mm to 0.2 mm) thinner than 0.6 mm can be obtained. A measurement sample having a thickness of 0.6 mm may be prepared by forming and superimposing the pressure-sensitive adhesive layers. It is preferable that the measurement sample obtained by the above superposition is then cured at room temperature for 12 hours or more (for example, about 24 hours) and then subjected to the measurement of the light transmittance. In the examples described later, the pressure-sensitive adhesive composition is applied to the peel-off surface of the same peel-off liner used for producing each pressure-sensitive adhesive sheet, dried at 100 ° C. for 2 minutes, and the thickness is about 0.1 mm on the peel-off surface. The pressure-sensitive adhesive layer was formed, and 6 layers of the pressure-sensitive adhesive layer were superposed to prepare a measurement sample having a thickness of 0.6 mm, which was cured at room temperature for 24 hours, and then the light transmittance was measured.

In general, the pressure-sensitive adhesive is amorphous and does not show remarkable optical anisotropy. Therefore, the light transmittance in the thickness direction measured for the pressure-sensitive adhesive having a thickness of 0.6 mm can be measured for the pressure-sensitive adhesive having a width of 0.6 mm. It can be treated as a characteristic that reflects the light transmittance in the width direction. Therefore, the pressure-sensitive adhesive layer having a lower 0.6 mm light transmittance obtained by the above measurement method tends to exhibit higher horizontal light-shielding property. By limiting the 0.6 mm light transmittance to 5% or less, even if the thickness of the pressure-sensitive adhesive layer is larger than 25 mm, light leakage through the pressure-sensitive adhesive layer in the width direction is accurately prevented or suppressed. be able to. The 0.6 mm light transmittance of the pressure-sensitive adhesive layer is preferably 3% or less, more preferably 1% or less, still more preferably, from the viewpoint of further enhancing the horizontal light-shielding property or enabling sufficient horizontal light-shielding even with a narrower width. Is 0.5% or less, particularly preferably 0.1% or less. The lower limit of the 0.6 mm light transmittance is not particularly limited, and may be substantially 0%, that is, below the detection limit.

The method for adjusting the 0.6 mm light transmittance of the pressure-sensitive adhesive layer is not particularly limited, and various known methods can be adopted. A typical example of such a method is a method of incorporating a colorant in the pressure-sensitive adhesive layer. This method is convenient because the 0.6 mm light transmittance of the pressure-sensitive adhesive layer can be easily adjusted to a desired value depending on the selection and amount of the colorant used. As the colorant, various materials that can be attenuated by reflecting and / or absorbing the light traveling in the pressure-sensitive adhesive layer can be used. The color of the colorant is not particularly limited and may be colored or colorless. Here, "colored" means including black and metallic colors. In addition, "colorless" means including white. The color of the colorant can be, for example, black, gray, white, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl, or the like. The colorant can typically be contained in the pressure-sensitive adhesive layer in a dispersed state (which can be a dissolved state) in the constituent materials of the pressure-sensitive adhesive layer.

(Base polymer)
In the technique disclosed herein, the type of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited. The pressure-sensitive adhesives include various rubber-like polymers such as acrylic polymers, rubber-based polymers, polyester-based polymers, urethane-based polymers, polyether-based polymers, silicone-based polymers, polyamide-based polymers, and fluorine-based polymers, which are known in the field of pressure-sensitive adhesives. It may contain one or more of the above as a base polymer. From the viewpoint of adhesive performance, cost, and the like, an adhesive containing an acrylic polymer or a rubber polymer as a base polymer can be preferably adopted. Of these, a pressure-sensitive adhesive (acrylic pressure-sensitive adhesive) using an acrylic polymer as a base polymer is preferable. Hereinafter, a pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive, that is, a pressure-sensitive adhesive sheet having an acrylic-based pressure-sensitive adhesive layer will be mainly described, but the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed herein is composed of an acrylic pressure-sensitive adhesive. It is not intended to be limited to just what.

The "base polymer" of the pressure-sensitive adhesive refers to the main component of the rubber-like polymer contained in the pressure-sensitive adhesive. The rubber-like polymer refers to a polymer that exhibits rubber elasticity in a temperature range near room temperature. Further, in this specification, the “main component” refers to a component contained in excess of 50% by weight unless otherwise specified.
Further, the "acrylic polymer" refers to a polymer containing a monomer unit derived from a monomer having at least one (meth) acryloyl group in one molecule as a monomer unit constituting the polymer. Hereinafter, a monomer having at least one (meth) acryloyl group in one molecule is also referred to as an “acrylic monomer”. Therefore, the acrylic polymer in this specification is defined as a polymer containing a monomer unit derived from an acrylic monomer. A typical example of the acrylic polymer is an acrylic polymer in which the proportion of the acrylic monomer in the total monomer components used in the synthesis of the acrylic polymer is more than 50% by weight.
In addition, "(meth) acryloyl" means acryloyl and methacryloyl comprehensively. Similarly, "(meth) acrylate" means acrylate and methacrylate, and "(meth) acrylic" means acrylic and methacrylic, respectively.

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 submonomer having copolymerizability with the main monomer is preferable. Here, the main monomer means a component that occupies more than 50% by weight of the monomer composition in the above-mentioned monomer raw material.

As the alkyl (meth) acrylate, for example, a compound represented by the following formula (1) can be preferably used.
CH ₂ = C (R ¹ ) COOR ² (1)
Here, R ¹ in the above formula (1) is a hydrogen atom or a methyl group. Further, R ² is a chain alkyl group having 1 to 20 carbon atoms. Hereinafter, such a range of the number of carbon atoms may be expressed as "C _1-20 ". From the viewpoint of the storage elastic modulus of the pressure-sensitive adhesive, alkyl (meth) acrylate in which R ² is a chain alkyl group of C _1-14 (for example, C _2-10 , typically C _4-8 ) is used as the main monomer. It is appropriate to do. From the viewpoint of adhesive properties, a R ¹ is a hydrogen atom an alkyl acrylate R ² is a linear alkyl group of C _4-8 (hereinafter, simply referred to as C _4-8 alkyl acrylates.) To the main monomer Is preferable.

Examples of the alkyl (meth) acrylate in which R ² is a C _1-20 chain alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl. (Meta) acrylate, isobutyl (meth) acrylate, s-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 Examples thereof include (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecil (meth) acrylate, and ecocil (meth) acrylate. .. These alkyl (meth) acrylates can be used alone or in combination of two or more. Preferred alkyl (meth) acrylates include n-butyl acrylate (BA) and 2-ethylhexyl acrylate (2EHA).

The proportion of alkyl (meth) acrylate in all the monomer components used in the synthesis of the acrylic polymer is preferably 70% by weight or more, more preferably 85% by weight or more, and further preferably 90% by weight or more. The upper limit of the proportion of the alkyl (meth) acrylate is not particularly limited, but is usually preferably 99.5% by weight or less (for example, 99% by weight or less). Alternatively, the acrylic polymer may be substantially obtained by polymerizing only an alkyl (meth) acrylate. When C _4-8 alkyl acrylate is used as the monomer component, the proportion of C _4-8 alkyl acrylate in the alkyl (meth) acrylate contained in the monomer component is preferably 70% by weight or more. It is more preferably 90% by weight or more, and further preferably 95% by weight or more (typically 99 to 100% by weight). The technique disclosed herein can be preferably carried out in an embodiment in which 50% by weight or more (typically 60% by weight or more) of all monomer components is BA. In a preferred embodiment, the proportion of BA in the total monomer component may be 70% by weight or more, 80% by weight or more, and even 90% by weight or more. The total monomer component may further contain 2EHA in a smaller proportion than BA.

The acrylic polymer in the technique disclosed herein may be copolymerized with a monomer (other monomer) other than the above as long as the effect of the present invention is not significantly impaired. The other monomers can be used, for example, for the purpose of adjusting the glass transition temperature (Tg) of the acrylic polymer, adjusting the adhesive performance (for example, peelability), and the like. For example, as a monomer capable of improving the cohesive force and heat resistance of the pressure-sensitive adhesive, a sulfonic acid group-containing monomer, a phosphoric acid group-containing monomer, a cyano group-containing monomer, vinyl esters, an alicyclic (meth) acrylate, and an aromatic vinyl compound. And so on. Among these, vinyl esters can be mentioned as a preferable example. Specific examples of vinyl esters include vinyl acetate (VAc), vinyl propionate, vinyl laurate and the like. Of these, VAc is preferable. The amount of VAc used can be, for example, about 3.5 to 10% by weight (preferably about 4 to 7% by weight) of all the monomer components.

Further, as other monomers which can contribute to the improvement of adhesive strength by introducing a functional group which can be a cross-linking base point into an acrylic polymer, a hydroxyl group (OH group) -containing monomer, a carboxy group-containing monomer, an acid anhydride group-containing monomer, and an amide Examples thereof include group-containing monomers, amino group-containing monomers, imide group-containing monomers, epoxy group-containing monomers, (meth) acryloylmorpholin, vinyl ethers and the like.
As a preferred example of the acrylic polymer in the technique disclosed herein, an acrylic polymer in which a carboxy group-containing monomer is copolymerized as the other monomer can be mentioned. Examples of the carboxy group-containing monomer include acrylic acid (AA), methacrylic acid (MAA), carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. Will be done. Of these, AA and MAA are preferable.
As another preferable example, an acrylic polymer in which a hydroxyl group-containing monomer is copolymerized as the other monomer can be mentioned. Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. ) Hydroxyalkyl (meth) acrylate such as acrylate; Polypropylene glycol mono (meth) acrylate; N-hydroxyethyl (meth) acrylamide and the like can be mentioned. Among them, preferred hydroxyl group-containing monomers include hydroxyalkyl (meth) acrylates in which the alkyl group is linear with 2 to 4 carbon atoms.

The above-mentioned "other monomers" may be used alone or in combination of two 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 all the monomer components, and is about 30% by weight or less (typically 0.01). ~ 30% by weight, for example 0.1 to 10% by weight).
When a carboxy group-containing monomer is used as the other monomer, the content thereof is approximately 0.1 to 10% by weight (for example, 0.2 to 8% by weight, typically 0.5 to 5% by weight) of all the monomer components. ) Is appropriate. When a hydroxyl group-containing monomer is used as the other monomer, the content thereof is approximately 0.001 to 10% by weight (for example, 0.01 to 5% by weight, typically 0.02 to 2% by weight) of all the monomer components. Is appropriate.

The copolymer composition of the acrylic polymer is appropriately designed so that the glass transition temperature (Tg) of the polymer is −15 ° C. or lower (typically −70 ° C. or higher and −15 ° C. or lower). .. The Tg of the acrylic polymer is preferably −25 ° C. or lower (for example, −60 ° C. or higher and −25 ° C. or lower), more preferably −40 ° C. or lower (for example, −60 ° C. or higher and −40 ° C. or lower). It is preferable that the Tg of the acrylic polymer is not more than the above-mentioned upper limit value from the viewpoint of sticking workability of the pressure-sensitive adhesive sheet.

The Tg of the acrylic polymer can be adjusted by appropriately changing the monomer composition (that is, the type and amount ratio of the monomers used in the synthesis of the polymer). Here, the Tg of the acrylic polymer means the Tg obtained by the Fox formula based on the composition of the monomer component used in the synthesis of the polymer. As shown below, the Fox formula is a relational formula between the Tg of the copolymer and the glass transition temperature Tgi of the homopolymer obtained by homopolymerizing each of the monomers constituting the copolymer.
1 / Tg = Σ (Wi / Tgi)
In the Fox formula, Tg is the glass transition temperature (unit: K) of the copolymer, Wi is the weight fraction of the monomer i in the copolymer (copolymerization ratio based on the weight), and Tgi is the monomer i. Represents the glass transition temperature (unit: K) of the homopolymer.

As the glass transition temperature of the homopolymer used for calculating Tg, the value described in the publicly known material shall be used. For example, for the monomers listed below, the following values are used as the glass transition temperature of the homopolymer of the monomer.
2-Ethylhexyl acrylate-70 ° C
n-Butyl acrylate -55 ° C
Ethyl acrylate-22 ° C
Methyl acrylate 8 ℃
Methyl methacrylate 105 ° C
2-Hydroxyethyl acrylate -15 ° C
4-Hydroxybutyl acrylate-40 ° C
Vinyl acetate 32 ° C
Styrene 100 ° C
Acrylic acid 106 ℃
Methacrylic acid 228 ° C

For the glass transition temperature of homopolymers of monomers other than those exemplified above, the numerical values described in "Polymer Handbook" (3rd edition, John Wiley & Sons, Inc., 1989) shall be used. The highest value is adopted for the monomers for which multiple types of values are described in this document.

For monomers for which the glass transition temperature of the homopolymer is not described in the above document, the value obtained by the following measurement method shall be used.
Specifically, in a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, 100 parts by weight of a monomer, 0.2 parts by weight of 2,2'-azobisisobutyronitrile, and acetate as a polymerization solvent. Add 200 parts by weight of ethyl and stir for 1 hour while flowing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature is raised to 63 ° C. and the reaction is carried out for 10 hours. Then, the mixture is cooled to room temperature to obtain a homopolymer solution having a solid content concentration of 33% by weight. Next, this homopolymer solution is cast-coated on a release liner and dried to prepare a test sample (sheet-shaped homopolymer) having a thickness of about 2 mm. This test sample is punched into a disk shape with a diameter of 7.9 mm, sandwiched between parallel plates, and shear strain with a frequency of 1 Hz using a viscoelasticity tester (manufactured by TA Instruments Japan, model name "ARES"). The viscoelasticity is measured in the shear mode at a heating rate of −70 ° C. to 150 ° C. and 5 ° C./min in the temperature range, and the temperature (G” curve corresponding to the peak top temperature of the shear loss elastic modulus G ”is The maximum temperature) is defined as Tg of the homopolymer.

The method for obtaining the acrylic polymer is not particularly limited, and various polymerization methods known as synthetic methods for the 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 adopted as appropriate. For example, a solution polymerization method can be preferably used. As a monomer supply method for solution polymerization, a batch charging method, a continuous supply (dropping) method, a divided feeding (dropping) method, or the like in which all the monomer raw materials are supplied at once can be appropriately adopted. The polymerization temperature can be appropriately selected depending on the type of monomer and solvent used, the type of polymerization initiator, etc., and may be, for example, about 20 ° C. to 170 ° C. (typically 40 ° C. to 140 ° C.). it can. In a preferred embodiment, a polymerization temperature of about 75 ° C. or lower (more preferably about 65 ° C. or lower, for example, about 45 ° C. to 65 ° C.) can be adopted.

The solvent (polymerization solvent) used for solution polymerization can be appropriately selected from conventionally known organic solvents. For example, aromatic compounds such as toluene (typically aromatic hydrocarbons); acetate esters such as ethyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; 1,2-dichloroethane and the like. Alkanes halogenated; lower alcohols such as isopropyl alcohol (for example, monohydric alcohols having 1 to 4 carbon atoms); ethers such as tert-butyl methyl ether; ketones such as methyl ethyl ketone; etc. Any one kind of solvent or two or more kinds of mixed solvents can be used.

The initiator used for the polymerization can be appropriately selected from conventionally known polymerization initiators according to the type of polymerization method. For example, one or more azo polymerization initiators such as 2,2'-azobisisobutyronitrile (AIBN) can be preferably used. Other examples of polymerization initiators include persulfates such as potassium persulfate; peroxide-based initiators such as benzoyl peroxide and hydrogen peroxide; substituted ethane-based initiators such as phenyl-substituted ethane; aromatic carbonyl compounds. ; Etc. can be mentioned. Yet another example of the polymerization initiator is a redox-based initiator in which a peroxide and a reducing agent are combined. Such a polymerization initiator can be used alone or in combination of two or more. The amount of the polymerization initiator used may be a normal amount, for example, about 0.005 to 1 part by weight (typically 0.01 to 1 part by weight) with respect to 100 parts by weight of all the monomer components. You can choose from a range.

According to the above solution polymerization, a polymerization reaction solution in which the acrylic polymer is dissolved in an organic solvent can be obtained. The pressure-sensitive adhesive layer in the technique disclosed herein may be formed from the above-mentioned polymerization reaction solution or a pressure-sensitive adhesive composition containing an acrylic polymer solution obtained by subjecting the reaction solution to an appropriate post-treatment. As the acrylic polymer solution, a solution prepared by preparing the polymerization reaction solution to an appropriate viscosity (concentration) 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, etc.) and dissolving the acrylic polymer in an organic solvent may be used. Good.

The weight average molecular weight of the base polymer (preferably the acrylic polymer) in the technology disclosed herein (Mw) of, is not, may be in the range, for example 10 × 10 ⁴ ~500 × 10 ⁴ particularly limited. From the viewpoint of adhesive performance, the Mw of the base polymer is in the range of 10 × 10 ^{4 to} 150 × 10 ⁴ (for example, 20 × 10 ⁴ to 75 × 10 ⁴ , typically 35 × 10 ^{4 to} 65 × 10 ⁴ ). It is preferable to have. Here, Mw refers to a standard polystyrene-equivalent value obtained by GPC (gel permeation chromatography). As the GPC apparatus, for example, a model name "HLC-8320GPC" (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) can be used.

(Adhesive imparting agent)
The pressure-sensitive adhesive layer disclosed herein may contain a tackifier. The tackifier is not particularly limited, and for example, a rosin-based tackifier resin, a terpene-based tackifier resin, a hydrocarbon-based tackifier resin, an epoxy-based tackifier resin, a polyamide-based tackifier resin, and an elastomer-based tackifier resin, Various tackifier resins such as phenol-based tackifier resins and ketone-based tackifier resins can be used. Such tackifiers can be used alone or in combination of two or more. When an acrylic polymer is used as the base polymer, it is preferable to use a rosin-based tackifier resin (for example, polymerized rosin ester) or a terpene-based tackifier resin (for example, terpene phenol resin).

Specific examples of the rosin-based tackifier resin include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; modified rosins obtained by modifying these unmodified rosins by hydrogenation, disproportionation, polymerization, etc. Hydrogenated rosins, disproportionated rosins, polymerized rosins, other chemically modified rosins, etc.); various other rosin derivatives; etc. Examples of the above rosin derivatives include unmodified rosins esterified with alcohols (ie, esterified rosins) and modified rosins (hydrogenated rosins, disproportionated rosins, polymerized rosins, etc.) esterified with alcohols. Rosin esters such as those obtained (ie, esterified products of modified rosins); unsaturated fatty acid-modified rosins obtained by modifying unmodified rosins and modified rosins (hydrogenated rosins, disproportionated rosins, polymerized rosins, etc.) with unsaturated fatty acids. Unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; unmodified rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), unsaturated fatty acid-modified rosin or unsaturated fatty acid Rosin alcohols obtained by reducing carboxyl groups in modified rosin esters; metal salts of rosins (particularly rosin esters) such as unmodified rosins, modified rosins, and various rosin derivatives; rosins (unmodified rosins, modified rosins, Examples thereof include a rosin phenol resin obtained by adding phenol to various rosin derivatives) with an acid catalyst and thermally polymerizing the resin.

Examples of terpene-based tackifier resins are terpene resins such as α-pinene polymer, β-pinene polymer, and dipentene polymer; these terpene resins are modified (phenolic modification, aromatic modification, hydrogenation modification, hydrocarbons). Modified terpene resin (modified, etc.); etc. Examples of the modified terpene resin include terpene phenol resin, styrene modified terpene resin, aromatic modified terpene resin, hydrogenated terpene resin and the like.

Examples of hydrocarbon-based tackifier resins include aliphatic hydrocarbon resins, aromatic hydrocarbon resins, aliphatic cyclic hydrocarbon resins, aliphatic / aromatic petroleum resins (styrene-olefin copolymers, etc.) ), Various hydrocarbon-based resins such as aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, kumaron-based resins, and kumaron-inden-based resins.

The softening point of the tackifier resin is not particularly limited. In one aspect, as the tackifier resin, one having a softening point (softening temperature) of about 80 ° C. or higher (preferably about 110 ° C. or higher, more preferably about 135 ° C. or higher) can be preferably used. A terpene-based tackifier resin (terpene phenol resin or the like) or a rosin-based tackifier resin (esterified product of polymerized rosin) having such a softening point can be preferably used. For example, a terpene phenol resin having a softening point of about 135 ° C. or higher (further, about 140 ° C. or higher) can be preferably used. The upper limit of the softening point of the tackifier resin is not particularly limited, and can be, for example, about 200 ° C. or lower (typically about 180 ° C. or lower). The softening point of the tackifier resin can be measured based on the softening point test method (ring ball method) specified in JIS K2207.

The amount of the tackifying resin used is not particularly limited, and can be appropriately set according to the desired adhesive performance (adhesive strength, etc.). For example, based on the solid content, the ratio of the tackifier resin to about 10 to 100 parts by weight (more preferably about 15 to 80 parts by weight, still more preferably about 20 to 60 parts by weight) with respect to 100 parts by weight of the acrylic polymer. It is preferable to use in.

As an example of a suitable composition of the acrylic pressure-sensitive adhesive disclosed herein, a pressure-imparting resin (for example, terpenephenol resin) having a softening point of 135 ° C. or higher is added in an amount of 20 to 60 parts by weight based on 100 parts by weight of the acrylic polymer. The composition including is mentioned.

Another example of a suitable composition of the acrylic pressure-sensitive adhesive disclosed herein is a composition containing a rosin-based pressure-sensitive adhesive resin (for example, a polymerized rosin ester) and a terpene-based pressure-sensitive adhesive resin (for example, a terpene phenol resin) in combination. Be done. With such a composition, better adhesive properties can be exhibited. The weight ratio of the rosin-based pressure-sensitive adhesive resin to the terpene-based pressure-sensitive adhesive resin can be, for example, in the range of 5/95 to 95/5, and may be in the range of 10/90 to 90/10, and may be in the range of 20/80 to 20/80. It may be in the range of 80/20 or in the range of 30/70 to 70/30.

Acrylic pressure-sensitive adhesive disclosed herein hydroxyl value may contain higher tackifier resin T _H1 than 50 mg KOH / g. The hydroxyl value of the tackifier resin _{T H1,} from the viewpoint of adhesive properties improve, for example, may be at 60 mg KOH / g or more, may be 70 mgKOH / g or more, may be 80 mg KOH / g or more, may be 90 mgKOH / g or more. The hydroxyl value of the tackifier resin _{T H1,} from the viewpoint of compatibility with the acrylic polymer, usually is suitably less 300 mgKOH / g, is preferably from 250 mgKOH / g, 200 mg KOH / g or less (e.g., 150 mgKOH / g or less ) May be used.

Examples of suitable compositions of the acrylic pressure-sensitive adhesive as disclosed herein, in combination with the tackifier resin T _H1, different tackifying resin T _H2 hydroxyl value 5 mgKOH / g or more, the tackifier as resin T _H1, the The composition to be included is mentioned. The hydroxyl value of differences between the tackifier resin _{T H1} and the tackifier resin _{T H2} is preferably 10 mgKOH / g or more (e.g. 20 mgKOH / g or higher), may be 30 mgKOH / g or more, may be 40 mg KOH / g or more. The hydroxyl value of the tackifier resin T _H2 may be higher than the hydroxyl value of the tackifier resin T _H1, may be low. In one embodiment, the hydroxyl value of the tackifier resin T _H2 may be preferably adopted a combination higher than the hydroxyl value of the tackifier resin T _H1. Examples of suitable compositions of the acrylic pressure-sensitive adhesive disclosed herein, the tackifier resin _{T H1} a hydroxyl value of 75 mgKOH / g or less (e.g., 70 mgKOH / g or less), a hydroxyl value of 80 mg KOH / g or more (e.g. 90mgKOH A composition containing a tackifier resin _{TH2 of (} / g or more) in combination can be mentioned.

Acrylic pressure-sensitive adhesive disclosed herein has an acid value may include high tackifier resin T _A1 than 20 mgKOH / g. The acid number of the tackifier resin _{T A1} may be for example 30 mgKOH / g or more, may be 40 mg KOH / g or more. Further, from the viewpoint of weather resistance of the adhesive, the acid value of the tackifier resin _{T A1} is generally less preferably 150 mgKOH / g, it may be below 100 mg KOH / g, or below 70 mgKOH / g.
The hydroxyl value of the tackifier resin T _A1 is not particularly limited. Tackifier resin T _A1 may be one corresponding to the tackifier resin T _H1 or tackifying resin T _H2 described above, or may be not applicable. The acid number of the tackifier resin _{T A1,} for example 50 mg KOH / g may be less, may be less 30 mgKOH / g, may be 20 mgKOH / g.
An example of a suitable composition of the acrylic pressure-sensitive adhesive disclosed herein is a composition containing the pressure-sensitive adhesive resin _TH1 and the pressure-sensitive adhesive resin _TA1 in combination.

The tackifier resin _TH1 , the tackifier resin _TH2 , and the tackifier resin T _A1 can be independently selected from the tackifier resins exemplified above having a desired hydroxyl value or acid value. For example, the tackifier resin _TH1 , the tackifier resin _TH2 , and the tackifier resin _TA1 can be independently selected from the group consisting of a rosin-based tackifier resin and a terpene-based tackifier resin (for example, a terpene phenol resin). it can.
The acid value and hydroxyl value of the tackifier resin can be measured by the potentiometric titration method specified in JIS K0070: 1992.

(Colorant)
A colorant can be contained in the pressure-sensitive adhesive layer. Thereby, the light transmission (light shielding property) of the pressure-sensitive adhesive layer can be adjusted. For example, the 0.6 mm light transmittance and the vertical light transmittance of the pressure-sensitive adhesive layer can be adjusted. Adjusting the light transmission (for example, vertical light transmission) of the pressure-sensitive adhesive layer can also help adjust the light transmission of the pressure-sensitive adhesive sheet containing the pressure-sensitive adhesive layer.

Conventionally known pigments and dyes can be used as the colorant. Pigments include, for example, zinc carbonate, zinc oxide, zinc sulfide, talc, kaolin, calcium carbonate, titanium oxide, silica, lithium fluoride, calcium fluoride, barium sulfate, alumina, zirconia, iron oxide, and iron hydroxide. , Chromium oxide type, Spinel type firing type, Chromic acid type, Chrome vermilion type, Navy blue type, Aluminum powder type, Bronze powder type, Silver powder type, Calcium phosphate and other inorganic pigments, Phthalocyanine type, Azo type, Condensed azo type , Azolake type, anthraquinone type, perylene / perinone type, indigo type, thioindigo type, isoindolinone type, azomethine type, dioxazine type, quinacridone type, aniline black type, triphenylmethane type, carbon black type and other organic pigments. Be done. Examples of the dye include azo dyes, anthraquinone, quinonephthalone, styryl, diphenylmethane, triphenylmethane, oxazine, triazine, xanthane, methane, azomethine, acridine and diazine. As the colorant, one type may be used alone or two or more types may be used in combination as appropriate.

Since the light-shielding property can be efficiently adjusted with a small amount of the colorant, the black colorant can be preferably used. Specific examples of black colorants include carbon black (furness black, channel black, acetylene black, thermal black, lamp black, pine smoke, etc.), graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, and cyanine. Examples thereof include black, activated carbon, ferrite (non-magnetic ferrite, magnetic ferrite, etc.), magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, anthraquinone-based colorant, and the like. Of these, carbon black is preferable.

Since the light-shielding property of the pressure-sensitive adhesive layer can be efficiently adjusted with a small amount of colorant, a particulate colorant (pigment) can be preferably used. In a preferred embodiment, a pigment having an average particle size of 10 nm to 500 nm, more preferably 10 nm to 120 nm (for example, a particulate black colorant such as carbon black) can be used. Unless otherwise specified, the "average particle size" in the present specification means the particle size (50% volume) at an integrated value of 50% in the particle size distribution measured based on the particle size distribution measuring device based on the laser scattering / diffraction method. average particle diameter; _hereinafter refers to also) be abbreviated as _{D 50..}

The blending amount of the colorant can be set so as to form a pressure-sensitive adhesive layer satisfying a desired 0.6 mm light transmittance, and is not particularly limited. Usually, it is suitable to be 0.5 parts by weight or more with respect to 100 parts by weight of the base polymer, preferably 1.0 part by weight or more, and more preferably 1.5 parts by weight or more. Further, the blending amount of the colorant can be, for example, 15 parts by weight or less with respect to 100 parts by weight of the base polymer. From the viewpoint of suppressing the deterioration of adhesive properties that may occur due to the blending of the colorant, the blending amount of the colorant is usually preferably 10 parts by weight or less with respect to 100 parts by weight of the base polymer, and 5 parts by weight or less. It is preferably 3 parts by weight or less, and more preferably 3 parts by weight or less. In a preferred embodiment, the blending amount of the colorant with respect to 100 parts by weight of the base polymer can be 2.5 parts by weight or less (more preferably 2.3 parts by weight or less, for example, 2 parts by weight or less).
The content of the colorant in the pressure-sensitive adhesive layer is usually preferably 0.3% by weight or more of the pressure-sensitive adhesive layer, preferably 0.5% by weight or more, and more preferably 1.0% by weight or more. preferable. The content of the colorant can be, for example, less than 10% by weight, preferably less than 5% by weight, more preferably less than 3.5% by weight, still more preferably less than 3.0% by weight. In a preferred embodiment, the colorant content of the pressure-sensitive adhesive layer can be less than 2.5% by weight (more preferably less than 2.2% by weight, for example less than 2.0% by weight).

The pressure-sensitive adhesive composition disclosed herein may contain a component that contributes to improving the dispersibility of the colorant. The dispersibility improving component can be, for example, a polymer, an oligomer, a liquid resin, a surfactant, or the like. The dispersibility improving component is preferably dissolved in the pressure-sensitive adhesive composition. The oligomer is, for example, low molecular weight polymer of one or a monomer component containing two or more acrylic monomers as exemplified above (e.g., Mw is approximately 10 × 10 than ^4, preferably less than 5 × 10 ⁴ Acrylic oligomer). The liquid resin is, for example, a tackifier resin having a softening point of about 50 ° C. or lower, more preferably about 40 ° C. or lower (typically, a rosin-based, terpene-based, hydrocarbon-based, or other tackifier resin, for example, hydrogenated rosin. It can be a methyl ester, etc.). With such a dispersibility improving component, it is possible to suppress uneven dispersion of a colorant (for example, a particulate black colorant such as carbon black), and eventually to suppress color unevenness of the pressure-sensitive adhesive layer. Therefore, it is possible to form an adhesive sheet having better appearance quality.

The content of the dispersibility improving component is not particularly limited, but from the viewpoint of suppressing the influence on the adhesive properties (for example, decrease in cohesiveness), it is usually about 20% by weight or less (preferably about 10% by weight or less) of the entire pressure-sensitive adhesive layer. , More preferably 7% by weight or less, for example, about 5% by weight or less). In one aspect, the content of the dispersibility improving component can be about 10 times or less (preferably about 5 times or less, for example, about 3 times or less) the weight of the colorant. On the other hand, from the viewpoint of preferably exerting the effect of the dispersibility improving component, the content thereof is usually about 0.2% by weight or more (typically about 0.5% by weight or more, preferably about 0.5% by weight or more) of the entire pressure-sensitive adhesive layer. Approximately 1% by weight or more) is appropriate. In one aspect, the content of the dispersibility improving component can be approximately 0.2 times or more (preferably approximately 0.5 times or more, for example, 1 time or more) the weight of the colorant.

(Crosslinking agent)
In the techniques disclosed herein, the pressure-sensitive adhesive composition used to form the pressure-sensitive adhesive layer may contain a cross-linking agent, if necessary. The type of the cross-linking agent is not particularly limited, and a conventionally known cross-linking agent can be appropriately selected and used. Examples of such cross-linking agents include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, and metal alkoxide-based cross-linking agents. Examples thereof include cross-linking agents, metal chelate-based cross-linking agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents, and amine-based cross-linking agents. The cross-linking agent may be used alone or in combination of two or more. Among them, from the viewpoint of improving the cohesive force, it is preferable to use an isocyanate-based cross-linking agent and / or an epoxy-based cross-linking agent, and it is particularly preferable to use an isocyanate-based cross-linking agent and an epoxy-based cross-linking agent in combination. The amount of the cross-linking agent used is not particularly limited. For example, it can be about 10 parts by weight or less with respect to 100 parts by weight of the base polymer (preferably an acrylic polymer), preferably about 0.005 to 10 parts by weight, more preferably about 0.01 to 5 parts by weight. You can select from the range of parts.

(Other additives)
The pressure-sensitive adhesive composition includes, if necessary, a pressure-sensitive adhesive composition such as a leveling agent, a cross-linking aid, a plasticizer, a softening agent, an antistatic agent, an antioxidant, an ultraviolet absorber, an antioxidant, and a light stabilizer. It may contain various additives that are common in the field of goods. As for such various additives, conventionally known ones can be used by a conventional method and do not particularly characterize the present invention, and thus detailed description thereof will be omitted.

The pressure-sensitive adhesive layer (layer composed of a pressure-sensitive adhesive) disclosed herein is formed of a water-based pressure-sensitive adhesive composition, a solvent-type pressure-sensitive adhesive composition, a hot-melt type pressure-sensitive adhesive composition, and an active energy ray-curable pressure-sensitive adhesive composition. It can be an adhesive layer. The water-based pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in which a pressure-sensitive adhesive (sticking agent layer-forming component) is contained in a solvent containing water as a main component (water-based solvent), and is typically water-dispersed. A 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 are included. Further, the solvent-type pressure-sensitive adhesive composition refers to a pressure-sensitive adhesive composition in the form of containing a pressure-sensitive adhesive in an organic solvent. The technique disclosed herein can be preferably carried out in an embodiment including a pressure-sensitive adhesive layer formed from a solvent-type pressure-sensitive adhesive composition from the viewpoint of pressure-sensitive adhesive properties and the like.

The pressure-sensitive adhesive layer disclosed herein can be formed by a conventionally known method. For example, a method (direct method) of forming the pressure-sensitive adhesive layer by directly applying (typically applying) the pressure-sensitive adhesive composition to the base film as described above and drying it can be adopted. Further, a method (transfer method) in which a pressure-sensitive adhesive composition is applied to a peelable surface (peeling surface) and dried to form a pressure-sensitive adhesive layer on the surface, and the pressure-sensitive adhesive layer is transferred to a base film. ) May be adopted. From the viewpoint of productivity, the transfer method is preferable. As the peeling surface, the surface of the peeling liner, the back surface of the base film that has been peeled off, or the like can be used. The pressure-sensitive adhesive layer disclosed herein is typically formed continuously, but is not limited to such a form, and may have a regular or random pattern such as a dot shape or a striped shape. It may be a formed pressure-sensitive adhesive layer.

The pressure-sensitive adhesive composition can be applied using a conventionally known coater such as a gravure roll coater, a die coater, or a bar coater. Alternatively, the pressure-sensitive adhesive composition may be applied by impregnation, a curtain coating method, or the like.
From the viewpoint of promoting the cross-linking reaction and improving the production efficiency, it is preferable to dry the pressure-sensitive adhesive composition under heating. The drying temperature can be, for example, about 40 to 150 ° C., and is usually preferably about 60 to 130 ° C. After the pressure-sensitive adhesive composition is dried, aging is further performed for the purpose of adjusting the component transfer in the pressure-sensitive adhesive layer, advancing the cross-linking reaction, alleviating the strain that may exist in the base film or the pressure-sensitive adhesive layer, and the like. May be good.

<Base film>
As the base film, a base film containing a resin film can be preferably used. The base film is typically an independently shape-retainable (independent) member. The substrate film in the techniques disclosed herein may be substantially composed of such a base film. Alternatively, the base film may include an auxiliary layer in addition to the base film. Examples of the auxiliary layer include a colored layer, a reflective layer, an undercoat layer, an antistatic layer and the like provided on the surface of the base film.

The resin film is a film containing a resin material as a main component (for example, a component contained in the resin film in an amount of more than 50% by weight). Examples of resin films include polyethylene (PE), polypropylene (PP), ethylene / propylene copolymer and other polyolefin resin films; polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN) and the like. Polyethylene resin film; vinyl chloride resin film; vinyl acetate resin film; polyimide resin film; polypropylene resin film; fluororesin film; cellophane; and the like. The resin film may be a rubber-based film such as a natural rubber film or a butyl rubber film. Among them, a polyester film is preferable from the viewpoint of handleability and processability, and a PET film is particularly preferable. In the present specification, the "resin film" is typically a non-porous sheet, and is a concept that is distinguished from so-called non-woven fabrics and woven fabrics (in other words, a concept excluding non-woven fabrics and woven fabrics). is there.

The resin film can contain a colorant. Thereby, the light transmission (light shielding property) of the resin film can be adjusted. For example, the vertical light transmittance and the 0.6 mm light transmittance of the resin film can be adjusted. Adjusting the light transmittance (for example, vertical light transmittance) of the resin film also adjusts the light transmittance of the base film containing the resin film and further the light transmission of the pressure-sensitive adhesive sheet containing the base film. Can be useful.

As the colorant, conventionally known pigments and dyes can be used as well as the colorant that can be contained in the pressure-sensitive adhesive layer. The color of the colorant is not particularly limited and may be colored or colorless. The color of the colorant can be, for example, black, gray, white, red, blue, yellow, green, yellow-green, orange, purple, gold, silver, pearl, or the like.

In one aspect, a black colorant can be preferably used because the light-shielding property (for example, vertical light transmittance) can be efficiently adjusted with a small amount of the colorant. Specific examples of the black colorant include those exemplified as a colorant that can be contained in the pressure-sensitive adhesive layer. In a preferred embodiment, a pigment having an average particle size of 10 nm to 500 nm, more preferably 10 nm to 120 nm (for example, a particulate black colorant such as carbon black) can be used.

In another aspect, the resin film may contain a white colorant. Examples of the white colorant include titanium oxide (titanium dioxide such as rutile type titanium dioxide and anatase type titanium dioxide), zinc oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide, tin oxide and barium oxide. Cesium oxide, titanium oxide, magnesium carbonate, calcium carbonate (light calcium carbonate, heavy calcium carbonate, etc.), barium carbonate, zinc carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, aluminum silicate, magnesium silicate , Calcium silicate, barium sulfate, calcium carbonate, barium stearate, zinc oxide, zinc sulfide, talc, silica, alumina, clay, kaolin, titanium phosphate, mica, gypsum, white carbon, diatomaceous soil, bentonite, lithopone, zeolite, sericite , Inorganic white colorants such as hydrated halloysite, acrylic resin particles, polystyrene resin particles, polyurethane resin particles, amide resin particles, polycarbonate resin particles, silicone resin particles, urea-formalin resin particles, melamine. Examples thereof include organic white colorants such as based resin particles.

The amount of the colorant used in the resin film is not particularly limited, and can be appropriately adjusted so as to impart desired optical characteristics. The amount of the colorant used is usually about 0.1 to 30% by weight based on the weight of the resin film, for example, 0.1 to 25% by weight (typically 0.1 to 20% by weight). ) Can be.

If necessary, the resin film may contain a filler (inorganic filler, organic filler, etc.), a dispersant (surfactant, etc.), an antioxidant, an antioxidant, an ultraviolet absorber, an antistatic agent, and a lubricant. , Various additives such as plasticizers may be blended. The blending ratio of various additives is usually less than 30% by weight (for example, less than 20% by weight, typically less than 10% by weight).

The resin film may have a single-layer structure, or may have a multi-layer structure of two layers, three layers or more. From the viewpoint of shape stability, the resin film preferably has a single-layer structure. In the case of a multi-layer structure, it is preferable that at least one layer (preferably all layers) is a layer having a continuous structure of the above resin (for example, a polyester resin). The method for producing the resin film may appropriately adopt a conventionally known method, and is not particularly limited. For example, conventionally known general film molding methods such as extrusion molding, inflation molding, T-die casting molding, and calender roll molding can be appropriately adopted.

The base film may be colored by a colored layer arranged on the surface of the base film (preferably a resin film). In the base film having a structure including the base film and the colored layer as described above, the base film may or may not contain a colorant. The colored layer may be arranged on one surface of the base film, or may be arranged on both surfaces, respectively. In the configuration in which the colored layers are arranged on both surfaces of the base film, the configurations of the colored layers may be the same or different.

Such a colored layer can typically be formed by applying a colored layer forming composition containing a colorant and a binder to a base film. As the colorant, conventionally known pigments and dyes can be used as well as the colorant that can be contained in the pressure-sensitive adhesive layer or the resin film. As the binder, a material known in the field of paint or printing can be used without particular limitation. For example, polyurethane, phenol resin, epoxy resin, urea melamine resin, polymethyl methacrylate and the like are exemplified. The composition for forming a colored layer may be, for example, a solvent type, an ultraviolet curable type, a thermosetting type or the like. The colored layer can be formed by using the means conventionally used for forming the colored layer without particular limitation. For example, a method of forming a colored layer (printing layer) by printing such as gravure printing, flexographic printing, and offset printing can be preferably adopted.

The colored layer may have a single-layer structure including one layer as a whole, or a multi-layer structure including two layers, three layers or more sub-colored layers. A colored layer having a multi-layer structure including two or more sub-colored layers can be formed, for example, by repeatedly applying (for example, printing) a composition for forming a colored layer. The color and blending amount of the colorant contained in each sub-colored layer may be the same or different. In the colored layer for imparting light-shielding property, it is particularly meaningful to have a multi-layer structure from the viewpoint of preventing the occurrence of pinholes and increasing the reliability of light leakage prevention.

The thickness of the entire colored layer is usually about 1 μm to 10 μm, preferably about 1 μm to 7 μm, and can be, for example, about 1 μm to 5 μm. In the colored layer including two or more sub-colored layers, the thickness of each sub-colored layer is usually preferably about 1 μm to 2 μm.

The thickness of the base film disclosed herein is not particularly limited. From the viewpoint of avoiding the pressure-sensitive adhesive sheet from becoming excessively thick, the thickness of the base film can be, for example, 200 μm or less, preferably 150 μm or less, and more preferably 100 μm or less. The thickness of the base film may be 70 μm or less, 50 μm or less, or 30 μm or less (for example, 25 μm or less) depending on the purpose and mode of use of the pressure-sensitive adhesive sheet. In one aspect, the thickness of the base film may be 20 μm or less, 15 μm or less, or 10 μm or less (for example, 5 μm or less). By reducing the thickness of the base film, the thickness of the pressure-sensitive adhesive layer can be further increased even if the total thickness of the pressure-sensitive adhesive sheets is the same. This can be advantageous from the viewpoint of impact resistance of the adhesive sheet. The lower limit of the thickness of the base film is not particularly limited. From the viewpoint of handleability (handleability) and processability of the pressure-sensitive adhesive sheet, the thickness of the base film is usually 0.5 μm or more (for example, 1 μm or more), preferably 2 μm or more, for example 4 μm or more. In one aspect, the thickness of the base film can be 6 μm or more, 8 μm or more, or 10 μm or more (for example, more than 10 μm).

The pressure-sensitive adhesive sheet disclosed herein has, for example, an embodiment in which a base film (typically a resin film) has a 0.6 mm light transmittance of, for example, 15% or less (preferably 10% or less, more preferably 5% or less). Can be carried out at. An adhesive sheet having such a structure including a base film can exhibit good horizontal light-shielding property. For a base film having a thickness of more than 25 μm, it is particularly significant that the 0.6 mm light transmittance of the base film satisfies the above numerical values. From the viewpoint of obtaining higher horizontal light-shielding property, the 0.6 mm light transmittance of the base film is preferably 3% or less, more preferably 1% or less, still more preferably 0.5% or less, and particularly preferably 0. It is 1% or less. The lower limit of the 0.6 mm light transmittance of the base film is not particularly limited, and may be substantially 0%, that is, below the detection limit. The 0.6 mm light transmittance of the base film can be measured in the same manner as the 0.6 mm light transmittance of the pressure-sensitive adhesive layer described above using the base film as a measurement sample.

The pressure-sensitive adhesive sheet disclosed herein can be implemented, for example, in a manner in which the vertical light transmittance of the base film is, for example, less than 5%. As a result, in the pressure-sensitive adhesive sheet containing the base film, good light-shielding property in the vertical direction (thickness direction of the pressure-sensitive adhesive sheet) can be realized. From the viewpoint of obtaining a higher level of light shielding property, the vertical light transmittance of the base film is preferably less than 3%, more preferably less than 1%, still more preferably less than 0.5%, and particularly preferably 0. It is less than 1%. The lower limit of the vertical light transmittance is not particularly limited, and may be substantially 0%, that is, below the detection limit. The vertical light transmittance of the base film can be measured in the same manner as the 0.6 mm light transmittance of the pressure-sensitive adhesive layer described above using the base film as a measurement sample.

The surface of the base film may be subjected to conventionally known surface treatments such as corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, acid treatment, alkali treatment, and application of an undercoat agent. Such a surface treatment may be a treatment for improving the adhesion between the base film and the pressure-sensitive adhesive layer, in other words, the anchoring property of the pressure-sensitive adhesive layer on the base film.

<Peeling liner>
In the technique disclosed herein, a release liner can be used when forming an adhesive layer, producing an adhesive sheet, storing the adhesive sheet before use, distributing it, processing the shape, and the like. The release liner is not particularly limited, and for example, a release liner having a release treatment layer on the surface of a liner base material such as a resin film or paper, a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, etc.) A release liner or the like made of a low adhesive material such as polypropylene can be used. The peeling treatment layer may be formed by surface-treating the liner base material with a peeling treatment agent such as silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

<Adhesive sheet>
The total thickness of the pressure-sensitive adhesive sheet (including the pressure-sensitive adhesive layer and the base film, but not the release liner) disclosed herein is not particularly limited. The total thickness of the pressure-sensitive adhesive sheet can be, for example, about 25.5 μm or more, 30 μm or more, 50 μm or more, or 60 μm or more. The upper limit of the total thickness of the pressure-sensitive adhesive sheet is typically 400 μm or less, preferably 300 μm or less, and may be 250 μm or less (for example, 200 μm or less). In one aspect, the total thickness of the pressure-sensitive adhesive sheet may be 120 μm or less, and may be 90 μm or less.

The pressure-sensitive adhesive sheet disclosed herein can be implemented in a mode in which the vertical light transmittance of the pressure-sensitive adhesive sheet is, for example, 5% or less. From the viewpoint of preferably realizing vertical light shielding and horizontal light shielding by one member, the vertical light transmittance of the adhesive sheet is preferably 3% or less, more preferably 1% or less, still more preferably 0.5% or less, particularly. It is preferably 0.1% or less. The lower limit of the vertical light transmittance is not particularly limited, and may be substantially 0%, that is, below the detection limit. The vertical light transmittance of the pressure-sensitive adhesive sheet can be measured in the same manner as the 0.6 mm light transmittance of the pressure-sensitive adhesive layer described above using the pressure-sensitive adhesive sheet as a measurement sample.

The pressure-sensitive adhesive sheet disclosed herein is a double-sided pressure-sensitive adhesive sheet including a first pressure-sensitive adhesive layer arranged on one surface of the base film and a second pressure-sensitive adhesive layer arranged on the other surface of the base film. It can be preferably carried out in the form of (double-sided adhesive adhesive sheet). The adhesive sheet having such a structure is highly useful as a joining member. Further, since it is easy to increase the ratio of the total thickness of the pressure-sensitive adhesive layer (total thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer) to the total thickness of the pressure-sensitive adhesive sheet, it is suitable for improving impact resistance. ing.

Here, at least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having a thickness of more than 25 μm and a light transmittance of 0.6 mm of 5% or less. The thickness of the other pressure-sensitive adhesive layer is not particularly limited, and may be, for example, 2 μm or more, typically 5 μm or more, preferably 10 μm or more, and more preferably 15 μm or more. As the thickness of the other pressure-sensitive adhesive layer increases, the impact resistance of the pressure-sensitive adhesive sheet tends to improve. From this point of view, the thickness of the other pressure-sensitive adhesive layer may be 20 μm or more, 25 μm or more, and similarly to one pressure-sensitive adhesive layer, more than 25 μm (for example, 27 μm or more, further 30 μm or more, or 35 μm or more ) May be used.

When the thickness of the other pressure-sensitive adhesive layer is larger than 25 μm, the 0.6 mm light transmittance of the other pressure-sensitive adhesive layer is also preferably 5% or less. As a result, both impact resistance and horizontal light-shielding property can be suitably compatible even in a narrow width. On the other hand, when the thickness of the other pressure-sensitive adhesive layer is 25 μm or less, the 0.6 mm light transmittance of the other pressure-sensitive adhesive layer is not particularly limited. The pressure-sensitive adhesive layer disclosed herein is, for example, a pressure-sensitive adhesive layer having a thickness of more than 25 μm and a light transmittance of 0.6 mm or less, which is arranged on one surface and is arranged on the other surface. It can also be preferably carried out in an embodiment in which the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer having a thickness of 25 μm or less and a light transmittance of more than 5% of 0.6 mm.

As a preferred embodiment of the pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet or double-sided pressure-sensitive adhesive sheet) disclosed herein, the 0.6 mm light transmittance of the layers contained in the pressure-sensitive adhesive sheet having a thickness of more than 25 μm is 5 in each case. % Or less (more preferably 3% or less, still more preferably 1% or less, typically 0.1% or less). According to the adhesive sheet having such a structure, good horizontal light-shielding property and impact resistance tend to be realized at the same time even in a narrow width. As a preferable aspect from the viewpoint of realizing higher horizontal light-shielding property, a layer having a thickness of 20 μm or more (more preferably a layer having a thickness of 15 μm or more, still more preferably a layer having a thickness of 10 μm or more) among the layers contained in the pressure-sensitive adhesive sheet. The 0.6 mm light transmittance of the above is 5% or less (more preferably 3% or less, further preferably 1% or less, typically 0.1% or less).

When the pressure-sensitive adhesive sheet disclosed herein is used for light reflection, the light reflectance of the surface of the pressure-sensitive adhesive sheet can be, for example, 40% or more, preferably 60% or more, and preferably 70% or more. More preferred. The upper limit of the light reflectance is ideally 100%, but from a practical point of view, it may be about 99% or less (for example, 95% or less, typically 92% or less).

The light reflectance (%) of the surface of the adhesive sheet is determined by irradiating one surface of the adhesive sheet (the surface for measuring the light reflectance) with light having a wavelength of 550 nm using a commercially available spectrophotometer. It is obtained by measuring the intensity of the light reflected by. As the spectrophotometer, for example, a spectrophotometer manufactured by Shimadzu Corporation (device name "MPS-2000") can be used. The same applies to the examples described later.

The total thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is not particularly limited. The total thickness of the pressure-sensitive adhesive layer can be, for example, more than 27 μm, typically more than 30 μm, preferably more than 35 μm, more preferably more than 40 μm. As the total thickness of the pressure-sensitive adhesive layer increases, the impact resistance of the pressure-sensitive adhesive sheet tends to improve. From this point of view, the total thickness of the pressure-sensitive adhesive layer may be more than 40 μm, more than 50 μm, more than 60 μm, and even more than 70 μm.

The ratio of the total thickness of the pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet to the total thickness of the pressure-sensitive adhesive sheet is not particularly limited. Here, the total thickness of the pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet is the total thickness of the pressure-sensitive adhesive layer provided on one surface of the base film and the pressure-sensitive adhesive layer provided on the other surface. Say. In the case of a single-sided pressure-sensitive adhesive sheet in which the pressure-sensitive adhesive layer is provided only on one surface of the base film, the thickness of the pressure-sensitive adhesive layer provided on the other surface is zero, and the thickness of the pressure-sensitive adhesive layer is zero on one of the above surfaces. The thickness of the provided pressure-sensitive adhesive layer and the total thickness of the pressure-sensitive adhesive layer are the same. In the pressure-sensitive adhesive sheet disclosed herein, for example, the ratio of the total thickness of the pressure-sensitive adhesive layer to the total thickness of the pressure-sensitive adhesive sheet is 40% or more (preferably 50% or more, typically more than 50%, more preferably. It can be carried out in an embodiment of 60% or more, more preferably 70% or more). With such a configuration, a higher level of impact resistance tends to be exhibited even in a narrow width as compared with the total thickness of the pressure-sensitive adhesive sheet. In one aspect, the ratio of the total thickness of the pressure-sensitive adhesive layer to the total thickness of the pressure-sensitive adhesive sheet may be 75% or more, and further 80% or more. The upper limit of the ratio of the total thickness of the pressure-sensitive adhesive layer to the total thickness of the pressure-sensitive adhesive sheet is not particularly limited, but is usually 95% or less, and preferably 90% or less.

In the pressure-sensitive adhesive layer having a thickness of more than 25 μm and a light transmittance of 0.6 mm or less contained in the pressure-sensitive adhesive sheet disclosed herein, the vertical light transmittance of the pressure-sensitive adhesive layer is not particularly limited. The vertical light transmittance of the pressure-sensitive adhesive layer may be, for example, 10% or more, 15% or more, or 20% or more. The pressure-sensitive adhesive sheet disclosed herein can be preferably carried out in an embodiment in which the vertical light transmittance of the pressure-sensitive adhesive layer is more than 25% (more preferably more than 30%). The upper limit of the vertical light transmittance of the pressure-sensitive adhesive layer is not particularly limited, and any value may be used as long as the 0.6 mm light transmittance of the pressure-sensitive adhesive layer is 5% or less. In this way, by increasing the permissible limit value of the vertical light transmittance within the range satisfying 0.6 mm light transmittance of 5% or less, the amount of the colorant required for adjusting to such vertical light transmittance can be reduced. Can be done. This is preferable from the viewpoint of suppressing uneven dispersion of the colorant (and thus uneven color of the pressure-sensitive adhesive layer) to obtain a pressure-sensitive adhesive sheet having good appearance quality. The vertical light transmittance of the pressure-sensitive adhesive layer can be measured in the same manner as the 0.6 mm light transmittance of the pressure-sensitive adhesive layer described above using the pressure-sensitive adhesive layer as a measurement sample.

The pressure-sensitive adhesive sheet disclosed herein preferably has a 180-degree peel strength of 3.0 N / 20 mm or more. According to the pressure-sensitive adhesive sheet exhibiting the above characteristics, a bonded structure having high durability tends to be realized even in a narrow width. The peel strength is preferably 3.5 N / 20 mm or more, and more preferably 4.0 N / 20 mm or more. The peel strength referred to here refers to a 180-degree peel strength (180-degree peeling adhesive strength) with respect to a stainless steel sheet.

The 180 degree peel strength can be measured as follows. Specifically, for a measurement sample obtained by cutting an adhesive sheet into a size of 20 mm in width and 100 mm in length, the adhesive surface of the measurement sample is the surface of a stainless steel plate (SUS304BA plate) under an environment of 23 ° C. and 50% RH. Then, a 2 kg roller is reciprocated once and crimped. After leaving this in the same environment for 30 minutes, using a universal tensile compression tester, the peel strength (N /) under the conditions of a tensile speed of 300 mm / min and a peeling angle of 180 degrees according to JIS Z 0237: 2000. 20 mm) is measured. As the universal tensile compression tester, for example, a "tensile compression tester, TG-1 kN" manufactured by Minebea can be used. The same measurement method is adopted in the examples described later.

<Use>
The pressure-sensitive adhesive sheet disclosed herein has good impact resistance even in a narrow width and is excellent in horizontal light-shielding property. Taking advantage of such characteristics, the pressure-sensitive adhesive sheet can be preferably applied to, for example, an electronic device provided with a liquid crystal display device that requires predetermined optical characteristics. More specifically, in a liquid crystal display device including an LCD unit and a BL unit, it can be preferably used for joining the LCD unit and the BL unit.

The pressure-sensitive adhesive sheet disclosed herein can be preferably used, for example, for joining an LCD unit of a portable electronic device to the BL unit. Non-limiting examples of such portable electronic devices include mobile phones, smartphones, tablet computers, laptop computers, various wearable devices (for example, wristwatch-type wristwatches, clips and straps, etc.). Modular type that is worn on a part of the body, eyewear type that includes glasses type (monocular type and binocular type, including head mount type), and clothing type that is attached to shirts, socks, hats, etc. in the form of accessories, for example. , Earwear type that attaches to the ear like an earphone), Digital camera, Digital video camera, Sound equipment (Portable music player, IC recorder, etc.), Computer (Calculator, etc.), Portable game equipment, Electronic dictionary, Electronic notebook, Electronic book , In-vehicle information devices, mobile radios, mobile TVs, mobile printers, mobile scanners, mobile modems, etc. In addition, in this specification, "portable" means that it is not enough to be portable, but to have a level of portability that an individual (standard adult) can carry relatively easily. It shall mean.

The pressure-sensitive adhesive sheet disclosed herein can be used in the form of a joining member processed into various outer shapes, for example, for joining an LCD unit and the BL unit or for other joining applications. A preferred form of such a joining member is a form having a narrow portion having a width of less than 2.0 mm (for example, less than 1.0 mm). Since the pressure-sensitive adhesive sheet disclosed herein includes a pressure-sensitive adhesive layer having a thickness of more than 25 μm and a light transmittance of 0.6 mm or less of 5% or less, it has a shape (for example, a frame shape) including such a narrow portion. Even if it is used as a joining member, it can exhibit good performance (impact resistance, horizontal light shielding property, etc.). In one aspect, the width of the narrow portion may be 0.7 mm or less, 0.5 mm or less, and may be about 0.3 mm or less. The lower limit of the width of the narrow portion is not particularly limited, but from the viewpoint of handleability of the pressure-sensitive adhesive sheet, 0.1 mm or more (typically 0.2 mm or more) is usually suitable.

The narrow portion is typically linear. Here, the linear shape is a concept that includes a linear shape, a curved line shape, a polygonal line shape (for example, an L-shape), an annular shape such as a frame shape or a circular shape, and a complex or intermediate shape thereof. .. The annular shape is not limited to the one formed by a curved line, and a part or all of the ring shape is formed linearly, for example, a shape along the outer circumference of a quadrangle (frame shape) or a shape along the outer circumference of a fan shape. It is a concept that includes a ring. The length of the narrow portion is not particularly limited. For example, in a form in which the length of the narrow portion is 10 mm or more (typically 20 mm or more, for example, 30 mm or more), the effect of applying the technique disclosed herein can be suitably exhibited.

The pressure-sensitive adhesive sheet disclosed herein can be preferably used in a shape in which the width W of the pressure-sensitive adhesive layer in the narrow portion is 50 times or less the thickness T of the pressure-sensitive adhesive layer. That is, it can be preferably used in a shape in which the W / T value is 50 or less (more preferably 40 or less, further preferably 30 or less, for example 25 or less) and attached to the adherend. For example, in an annular pressure-sensitive adhesive sheet used for joining an LCD unit of a liquid crystal display device and the BL unit, when the pressure-sensitive adhesive sheet has an adhesive layer having high light transmittance, one of the light emitted from the BL unit. The portion penetrates the adhesive layer diagonally (toward the LCD unit side) from the BL unit side end on the inner circumference of the pressure-sensitive adhesive layer to the LCD unit side end on the outer periphery of the pressure-sensitive adhesive layer. Light that is obliquely transmitted through the adhesive layer toward the LDC unit side in this way tends to cause inconveniences such as uneven brightness on the liquid crystal display surface. As the W / T value decreases, the proportion of light that passes through the pressure-sensitive adhesive layer in the width direction and that passes through the pressure-sensitive adhesive layer diagonally toward the LDC unit tends to increase. Therefore, it is of great significance to prevent or suppress light leakage in the width direction of the pressure-sensitive adhesive sheet by applying the technique disclosed herein.

Matters disclosed by this specification include:
(1) A base film and an adhesive layer arranged on at least one surface of the base film are provided.
The pressure-sensitive adhesive layer contains a colorant in the pressure-sensitive adhesive layer.
The pressure-sensitive adhesive layer is a pressure-sensitive adhesive sheet having a thickness of more than 25 μm and a light transmittance of 0.6 mm of 5% or less.
(2) The pressure-sensitive adhesive sheet according to (1) above, wherein all of the layers constituting the pressure-sensitive adhesive sheet having a thickness of more than 25 μm have a 0.6 mm light transmittance of 5% or less.
(3) The pressure-sensitive adhesive sheet according to (1) or (2) above, wherein the total thickness of the pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet is more than 50% of the total thickness of the pressure-sensitive adhesive sheet.
(4) The adhesive sheet according to any one of (1) to (3) above, wherein the vertical light transmittance of the adhesive sheet is 1% or less.
(5) The pressure-sensitive adhesive sheet according to any one of (1) to (4) above, wherein the vertical light transmittance of the pressure-sensitive adhesive layer is higher than 25%.
(6) The adhesive sheet according to any one of (1) to (5) above, wherein the adhesive sheet has a narrow portion and the width of the narrow portion is less than 2.0 mm.
(7) The pressure-sensitive adhesive sheet according to (6) above, wherein the width of the pressure-sensitive adhesive layer in the narrow portion is 50 times or less the thickness of the pressure-sensitive adhesive layer.
(8) It is configured as a double-sided pressure-sensitive adhesive sheet including a first pressure-sensitive adhesive layer arranged on one surface of the base film and a second pressure-sensitive adhesive layer arranged on the other surface of the base film. ,
Each of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer has a thickness of more than 25 μm and a light transmittance of 0.6 mm of 5% or less, any of the above (1) to (7). Adhesive sheet described in.
(9) The adhesive sheet according to any one of (1) to (8) above, which is used for joining the LCD unit and the BL unit in a liquid crystal display device including the LCD unit and the BL unit.

(10) The pressure-sensitive adhesive sheet according to any one of (1) to (9) above, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer.
(11) The pressure-sensitive adhesive layer contains an acrylic polymer in a proportion exceeding 50% by weight of the polymer component contained in the pressure-sensitive adhesive layer.
The acrylic polymer has the formula (1): as a monomer component.
CH ₂ = C (R ¹ ) COOR ² (1)
(R ¹ in the above formula (1) is a hydrogen atom or a methyl group, and R ² is a chain alkyl group having 1 to 20 carbon atoms.); An alkyl (meth) acrylate represented by The adhesive sheet according to any one of (1) to (10) above, which contains 70% by weight or more.
(12) The acrylic polymer further contains a functional group-containing monomer as the monomer component.
The functional group-containing monomers include acrylic acid, methacrylic acid, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate and 4 The pressure-sensitive adhesive sheet according to (11) above, which is at least one selected from the group consisting of -hydroxybutyl (meth) acrylate.
(13) The pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer includes an isocyanate-based cross-linking agent, an epoxy-based cross-linking agent, an oxazoline-based cross-linking agent, an aziridine-based cross-linking agent, a melamine-based cross-linking agent, and a peroxide-based cross-linking agent. The above (containing at least one cross-linking agent selected from the group consisting of a urea-based cross-linking agent, a metal alkoxide-based cross-linking agent, a metal chelate-based cross-linking agent, a metal salt-based cross-linking agent, a carbodiimide-based cross-linking agent and an amine-based cross-linking agent. The adhesive sheet according to any one of 10) to (12).
(14) The pressure-sensitive adhesive sheet according to (13) above, wherein the pressure-sensitive adhesive composition used for forming the pressure-sensitive adhesive layer contains a combination of an isocyanate-based cross-linking agent and an epoxy-based cross-linking agent.
(15) The pressure-sensitive adhesive layer includes a rosin-based pressure-sensitive adhesive resin, a terpene-based pressure-sensitive adhesive resin, a hydrocarbon-based pressure-sensitive adhesive resin, an epoxy-based pressure-sensitive adhesive resin, a polyamide-based pressure-sensitive adhesive resin, an elastomer-based pressure-sensitive adhesive resin, and a phenol-based pressure-sensitive adhesive resin. The pressure-sensitive adhesive sheet according to any one of (10) to (14) above, which comprises at least one type of pressure-sensitive adhesive resin selected from the group consisting of a resin and a ketone-based pressure-sensitive adhesive resin.
(16) The pressure-sensitive adhesive sheet according to (15) above, wherein the pressure-sensitive adhesive layer contains a rosin-based pressure-sensitive adhesive resin and a terpene phenol resin in a weight ratio of 5/95 to 95/5.
(17) The above-mentioned (15) or (16), wherein the pressure-sensitive adhesive layer contains 20 to 60 parts by weight of a terpene phenol resin having a softening point of 135 ° C. or higher with respect to 100 parts by weight of the acrylic polymer. Adhesive sheet.
(18) The pressure-sensitive adhesive layer, in combination with a hydroxyl value of 50 mg KOH / g higher than the tackifier resin _{T H1,} the hydroxyl value and the tackifier resin _{T H1} is a 5 mgKOH / g or more different tackifying resin _{T H2} , The adhesive sheet according to any one of (15) to (17) above.
(19) the pressure-sensitive adhesive layer has a hydroxyl value of 50 mg KOH / g higher than the tackifier resin _{T H1,} including acid value in combination with a 20 mgKOH / g higher than the tackifier resin _{T A1,} the (15) from (18 ) The adhesive sheet described in any of.
(20) The pressure-sensitive adhesive sheet according to any one of (1) to (19) above, wherein the colorant contains carbon black as a black colorant.
(21) The pressure-sensitive adhesive sheet according to (20) above, wherein the content of the colorant in the pressure-sensitive adhesive layer is 0.3% by weight or more and less than 3.0% by weight.

(22) A double-sided adhesive adhesive sheet used for joining the LCD unit and the BL unit in a liquid crystal display device including the LCD unit and the BL unit.
Base film and
A first pressure-sensitive adhesive layer arranged on one surface of the base film and
With a second pressure-sensitive adhesive layer disposed on the other surface of the substrate film,
The base film has a thickness of more than 25 μm and a light transmittance of 0.6 mm of 5% or less, or a thickness of 25 μm or less.
Both the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer have a thickness of more than 25 μm and a light transmittance of 0.6 mm of 5% or less.
The vertical light transmittance of the adhesive sheet is 1% or less,
The total thickness of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is larger than 50% of the total thickness of the pressure-sensitive adhesive sheet.
At least one of the first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer containing an acrylic polymer in a proportion of more than 50% by weight of the polymer component contained in the pressure-sensitive adhesive layer.
The acrylic pressure-sensitive adhesive layer is an adhesive sheet containing 0.3% by weight or more and less than 3.0% by weight of carbon black.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such examples. In the following description, "part" and "%" are based on weight unless otherwise specified.

<Example 1>
In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, a reflux condenser and a dropping funnel, 92 parts of BA, 5 parts of vinyl acetate, 2.9 parts of AA and 0.1 part of 2-hydroxyethyl acrylate as monomer components were added. , 30 parts of ethyl acetate and 120 parts of toluene as a polymerization solvent were charged, and the mixture was stirred for 2 hours while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, 0.2 parts of AIBN was added as a polymerization initiator, and solution polymerization was carried out at 60 ° C. for 6 hours to obtain a solution of an acrylic polymer. The Mw of the acrylic polymer was about 50 × 10 ^4.
Rosin-based resin A (polymerized rosin ester, trade name "Pencel D-125", softening point 120 to 130 ° C., Arakawa Chemical Industry) as a tackifier resin for 100 parts of the acrylic polymer contained in the acrylic polymer solution. 10 parts of rosin resin B (ununiform rosin ester, trade name "Superester A-100", softening point 95-105 ° C, manufactured by Arakawa Chemical Industry Co., Ltd.) and 10 parts of rosin phenol resin (trade name "" Tamanol 803L ”, softening point 145-160 ℃, manufactured by Arakawa Chemical Industry Co., Ltd.), carbon black dispersion (trade name“ N-DYM8715 Black ”, manufactured by Dainichi Seika Kogyo Co., Ltd.), and isocyanate-based cross-linking agent ( The pressure-sensitive adhesive composition A1 was prepared by adding 2 parts (trade name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd., solid content 75%). The pressure-sensitive adhesive composition A1 contains two parts of carbon black as a colorant with respect to 100 parts of the acrylic polymer.

As the peeling liner, two polyester peeling films (trade name "Diafoil MRF", thickness 38 μm, manufactured by Mitsubishi Polyester Co., Ltd.) having a peeled surface on one side were prepared. The pressure-sensitive adhesive composition A1 was applied to the peeled surface of these peeling liners so as to have a thickness of 28 μm after drying, and dried at 100 ° C. for 2 minutes. In this way, an adhesive layer was formed on each of the peeling surfaces of the two peeling liners.
As the base film, a transparent PET film having a thickness of 4.5 μm (trade name “Lumilar”, manufactured by Toray Industries, Inc.) and a black printing layer (colored layer) provided on the second surface of the PET film (base film). A base film having a total thickness of about 10 μm was prepared. The black printing layer was formed by printing using an ink composition containing a black colorant and using a gravure printing method. An adhesive layer formed on the two release liners is bonded to the first surface (first surface of the base film) and the second surface (surface of the colored layer) of the base film, respectively, in this example. (Transfer method) was produced. The release liner was left as it was on the pressure-sensitive adhesive layer and used to protect the surface (adhesive surface) of the pressure-sensitive adhesive layer.

<Example 2>
In this example, as the base film, a transparent PET film having a thickness of 25 μm (trade name “Lumirror”, manufactured by Toray Industries, Inc.) and a black printing layer (coloring) similar to Example 1 provided on the second surface of the PET film. A base film having a total thickness of about 30 μm composed of layers) was used. The amount of the pressure-sensitive adhesive composition A1 applied to the release film was adjusted so that the thickness after drying was 36 μm. The other points were the same as the production of the pressure-sensitive adhesive sheet according to Example 1, and the pressure-sensitive adhesive sheet according to this example was produced.

<Example 3>
In this example, as a base film, a 38 μm-thick PET film (trade name “Lumilar”, manufactured by Toray Co., Ltd.) in which a white pigment is kneaded is provided, and white, silver, and black are provided on the second surface of the PET film in this order. A base film having a total thickness of about 45 μm was used, which was composed of the printed layer (colored layer). The amount of the pressure-sensitive adhesive composition A1 applied to the release film was adjusted so that the thickness after drying was 30 μm. The pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition A1 was bonded only to the first surface of the base film. The other points were the same as the production of the pressure-sensitive adhesive sheet according to Example 1, and the pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet) according to this example was produced.

<Example 4>
In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, a reflux condenser and a dropping funnel, 95 parts of BA and 5 parts of AA as monomer components and 150 parts of toluene as a polymerization solvent were charged, and nitrogen gas was introduced. While stirring for 2 hours. After removing oxygen in the polymerization system in this way, 0.2 part of benzoyl peroxide was added as a polymerization initiator and solution-polymerized at 60 ° C. for 6 hours to obtain a solution of an acrylic polymer. The Mw of the acrylic polymer was about 60 × 10 ^4.
A terpenphenol resin as a tackifier resin (trade name "YS Polystar S-145", softening point of about 145 ° C., manufactured by Yasuhara Chemical Co., Ltd.) with respect to 100 parts of the acrylic polymer contained in the acrylic polymer solution. With 10 parts, 30 parts of terpenphenol resin (trade name "Tamanol 803L", softening point 145-160 ° C., manufactured by Arakawa Chemical Industry Co., Ltd.) and the above carbon black dispersion (including 2 parts of carbon black as a colorant). , 2 parts of isocyanate-based cross-linking agent (trade name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd., solid content 75%) and 0.03 part of epoxy-based cross-linking agent (trade name "TETRAD-C", manufactured by Mitsubishi Gas Chemical Co., Ltd.) And mixed with stirring to prepare a pressure-sensitive adhesive composition A2.
As the base film, a PET film having a thickness of 75 μm (trade name “Lumilar”, manufactured by Toray Industries, Inc.) kneaded with a black pigment was used. The amount of the pressure-sensitive adhesive composition A2 applied to the release film was adjusted so that the thickness after drying was 38 μm. In other respects, the pressure-sensitive adhesive sheet according to this example was produced in the same manner as in the production of the pressure-sensitive adhesive sheet according to Example 1.

<Example 5>
The pressure-sensitive adhesive composition A0 containing no colorant was prepared in the same manner as in the preparation of the pressure-sensitive adhesive composition A1 except that the carbon black dispersion was not added.
As the base film, a transparent PET film having a thickness of 12 μm (trade name “Lumilar”, manufactured by Toray Industries, Inc.) was used. The amount of the pressure-sensitive adhesive composition A0 applied to the release film was adjusted so that the thickness after drying was 19 μm. In other respects, the pressure-sensitive adhesive sheet according to this example was produced in the same manner as in the production of the pressure-sensitive adhesive sheet according to Example 1.

<Example 6>
In a reaction vessel equipped with a stirrer, a thermometer, a nitrogen gas introduction tube, a reflux condenser, and a dropping funnel, 70 parts of BA as a monomer component, 27 parts of 2EHA, 3 parts of AA and 0.05 part of 4-hydroxybutyl acrylate as a polymerization solvent. The mixture was charged with 135 parts of toluene and stirred for 2 hours while introducing nitrogen gas. After removing oxygen in 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 ° C. for 6 hours to obtain a toluene solution of an acrylic polymer. Mw of the acrylic polymer A was about 40 × 10 ^4.
Rosin resin A (polymerized rosin ester, trade name "Pencel D-125", softening point 120 to 130 ° C., manufactured by Arakawa Chemical Industry Co., Ltd.) 30 as a tackifier resin for 100 parts of the acrylic polymer contained in the toluene solution. An acrylic pressure-sensitive adhesive composition A3 was prepared by adding two parts and an isocyanate-based cross-linking agent (trade name "Coronate L", manufactured by Nippon Polyurethane Industry Co., Ltd., solid content 75%).
As the base film, a transparent PET film having a thickness of 25 μm (trade name “Lumilar”, manufactured by Toray Industries, Inc.) was used. The amount of the pressure-sensitive adhesive composition A3 applied to the release film was adjusted so that the thickness after drying was 38 μm. The other points were the same as the production of the pressure-sensitive adhesive sheet according to Example 1, and the pressure-sensitive adhesive sheet according to this example was produced.

<Example 7>
In Example 3, the pressure-sensitive adhesive composition A3 was used instead of the pressure-sensitive adhesive composition A1. The amount of the pressure-sensitive adhesive composition A3 applied to the release film was adjusted so that the thickness after drying was 20 μm. The base film is a 13 μm-thick PET film (trade name “Lumilar”, manufactured by Toray Industries, Inc.) in which a white pigment is kneaded, and printing provided on the second surface of the PET film in the order of white, silver, and black. A base film having a total thickness of about 20 μm, which was composed of a layer (colored layer), was used. The other points were the same as the production of the pressure-sensitive adhesive sheet according to Example 3, and the pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet) according to this example was produced.

<Example 8>
In this example, as the base film, a transparent PET film having a thickness of 12 μm (trade name “Lumirror”, manufactured by Toray Industries, Inc.) and a black printing layer (coloring) similar to Example 1 provided on the second surface of the PET film. A base film having a total thickness of about 17 μm composed of layers) was used. The amount of the pressure-sensitive adhesive composition A3 applied to the release film was adjusted so that the thickness after drying was 17 μm. The adhesive sheet according to this example was produced in the same manner as in Example 6 in other respects.

<Example 9>
In Example 2, the pressure-sensitive adhesive composition A3 was used instead of the pressure-sensitive adhesive composition A1. The adhesive sheet according to this example was produced in the same manner as in Example 2 in other respects.

<Example 10>
A 20 μm-thick pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition A3 was bonded to the first and second surfaces of the same base film used in Example 7. The adhesive sheet according to this example was produced in the same manner as in Example 6 in other respects.

[Evaluation]
For the pressure-sensitive adhesive sheet according to each example, the 0.6 mm light transmittance (%) of the pressure-sensitive adhesive layer, the vertical light transmittance (%) and the impact resistance of the pressure-sensitive adhesive sheet were measured or evaluated. For the adhesive sheets according to Examples 3 and 7, the reflectance (%) of the second surface of the adhesive sheet was also measured.

The impact resistance was evaluated for the adhesive sheets according to Examples 1, 2, 4 to 6 and 8 to 10 as follows.
That is, the pressure-sensitive adhesive sheet according to each example was processed into a frame shape having an outer circumference of 40 mm, a length of 60 mm, and a width of 1 mm. The peeling liner covering one of the adhesive surfaces of the frame-shaped adhesive sheet is peeled off, and the exposed adhesive surface is crimped to a stainless steel plate (SUS304BA plate) having a width of 60 mm, a length of 80 mm, and a thickness of 1 mm by reciprocating a 2 kg roller once. did. Immediately after that, the peeling liner covering the other adhesive surface is peeled off, an acrylic resin plate having a width of 40 mm, a length of 60 mm, and a thickness of 2 mm is placed on the exposed adhesive surface, and a load of 50 N is applied from the acrylic plate side for 10 seconds. It was crimped. This was cured for 24 hours in an environment of 23 ° C. and 50% RH, and used as an evaluation sample.
An impact was applied to the sample by free-falling the evaluation sample from a height of 1 m, and the presence or absence of peeling was visually confirmed between the adhesive sheet and the stainless steel plate and between the adhesive sheet and the acrylic resin plate. .. When no peeling was observed, the sample was freely dropped from a height of 1 m again, and the presence or absence of peeling was similarly confirmed. This drop test was repeated up to 40 times, and the number of times until peeling occurred was recorded. From the results, E (Excellent) was found to be peeling after 40 drops, G (Good) was found to be peeled from 31 to 40 times, and peeling was found after 21 to 30 drops. The impact resistance was evaluated as A (Acceptable) and P (Poor) when peeling was observed 20 times or less.

The obtained results are shown in Tables 1 and 2 together with the schematic configuration of the adhesive sheet according to each example.

From the results shown in Tables 1 and 2, it can be seen that the adhesive sheets of Examples 1, 2 and 4 provided with the adhesive layer thicker than 25 μm all show good bonding durability against drop impact even in a narrow width. .. Further, the pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets of Examples 1 to 4 all have a 0.6 mm light transmittance of 5% or less (specifically, less than 0.1%), and have high horizontal light-shielding properties even in a narrow width. It can be seen that it shows.

On the other hand, the pressure-sensitive adhesive sheets of Examples 5, 8 and 10 having a thickness of the pressure-sensitive adhesive layer of 25 μm or less tended to be inferior in impact resistance to the pressure-sensitive adhesive sheets of Examples 1, 2 and 4. Further, since the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheets of Examples 5 to 10 has a high light transmittance of 0.6 mm, the horizontal light-shielding property is lower than that of the pressure-sensitive adhesive sheets of Examples 1 to 4, and the thickness of the pressure-sensitive adhesive layer is particularly high. It was confirmed that Examples 6 and 9 having a size of more than 25 μm had poor horizontal light-shielding property.

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

1, 2 Adhesive sheet 10 Base film 10A 1st surface 10B 2nd surface 12 Resin film (base film)
14 Colored layer 21 1st adhesive layer 21A 1st adhesive surface 22 2nd adhesive layer 22A 2nd adhesive surface 31, 32 Release liner

Claims (10)

A substrate film and a pressure-sensitive adhesive sheet Ru and a disposed on at least one surface adhesive layer of the base film,
The base film contains a resin film containing a colorant, or has a colored layer arranged on the surface of the base film.
The pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed from a solvent-type pressure-sensitive adhesive composition, a hot-melt type pressure-sensitive adhesive composition, or an active energy ray-curable pressure-sensitive adhesive composition.
The pressure-sensitive adhesive layer has a single-layer structure.
The pressure-sensitive adhesive layer contains a colorant in the pressure-sensitive adhesive layer.
The pressure-sensitive adhesive layer has a thickness of more than 25 μm and a light transmittance of 5% or less at a length of 0.6 mm.
An adhesive sheet in which the total thickness of the pressure-sensitive adhesive layer contained in the pressure-sensitive adhesive sheet is 70% or more of the total thickness of the pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet according to claim 1, wherein all of the layers constituting the pressure-sensitive adhesive sheet having a thickness of more than 25 μm have a light transmittance of 5% or less at a length of 0.6 mm. The pressure-sensitive adhesive sheet according to claim 1 or 2 , wherein the vertical light transmittance of the pressure-sensitive adhesive sheet is 1% or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 3 , wherein the pressure-sensitive adhesive layer has a vertical light transmittance of more than 25%. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein the pressure-sensitive adhesive sheet has a narrow portion and the width of the narrow portion is less than 2.0 mm. The pressure-sensitive adhesive sheet according to claim 5 , wherein the width of the pressure-sensitive adhesive layer in the narrow portion is 50 times or less the thickness of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer formed from a solvent-type pressure-sensitive adhesive composition. It is configured as a double-sided pressure-sensitive adhesive sheet including a first pressure-sensitive adhesive layer arranged on one surface of the base film and a second pressure-sensitive adhesive layer arranged on the other surface of the base film.
The first pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer are both pressure-sensitive adhesive layers formed from a solvent-type pressure-sensitive adhesive composition, a hot-melt type pressure-sensitive adhesive composition, or an active energy ray-curable pressure-sensitive adhesive composition. The adhesive sheet according to any one of claims 1 to 7 , which has a single-layer structure, has a thickness of more than 25 μm, and has a light transmittance of 5% or less at a length of 0.6 mm. .. The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, which is configured as a single-sided pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer on only one side of the base film. The adhesive sheet according to any one of claims 1 to 9 , which is used for joining the liquid crystal display module unit and the backlight unit in a liquid crystal display device including the liquid crystal display module unit and the backlight unit.

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