Adhesive sheet

Abstract

To provide an adhesive sheet having such a form that an adhesive layer is laminated on a fiber substrate, and achieving both hot melt coating property and excellent adhesive performance.SOLUTION: An adhesive sheet including a fiber substrate and an adhesive layer laminated on the fiber substrate is such that: an adhesive forming the adhesive layer contains a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, a tackifier resin and a plasticizer; the adhesive has a shear viscosity at 195°C of 1,300 Pa s or more and 3,000 Pa s or less; the fiber substrate has a basis weight of 30 g / m2 or less, and a thickness of 60 μm or less; and an organic residual solvent content in the adhesive layer is less than 1,000 ppm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer containing a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound. [Background technology]

[0002] Generally, adhesives (also called pressure-sensitive adhesives; the same applies hereinafter) are in a soft solid (viscoelastic) state at temperatures around room temperature and have the property of easily adhering to an adherend when pressure is applied. Utilizing these properties, adhesives are widely used in various industrial fields, from home appliances to automobiles and office equipment, as a joining means with good workability and high adhesive reliability. A typical composition of such an adhesive is a composition containing a polymer that exhibits rubber elasticity at room temperature and a tackifying resin. For example, Patent Document 1 describes an adhesive containing a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound and a tackifying resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-216852 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, from the viewpoints of reducing environmental load and improving the working environment, there has been a demand for a reduction in the amount of organic solvents used, and in the field of pressure-sensitive adhesive sheets, there is a trend toward a preference for solvent-free pressure-sensitive adhesives such as hot-melt types. However, when attempting to improve adhesive performance (e.g., holding power and repulsion resistance) using hot-melt pressure-sensitive adhesives, the melt viscosity of the pressure-sensitive adhesive tends to increase. When the melt viscosity of the pressure-sensitive adhesive increases, for example, in a pressure-sensitive adhesive sheet in the form of a pressure-sensitive adhesive layer laminated on a fibrous substrate such as a nonwoven fabric, the impregnation of the pressure-sensitive adhesive into the fibrous substrate tends to decrease. Insufficient impregnation of the pressure-sensitive adhesive into the fibrous substrate can be a factor that impairs the original performance of the pressure-sensitive adhesive sheet in the form.

[0005] The present invention was created in consideration of the above circumstances, and aims to provide an adhesive sheet in which an adhesive layer is laminated on a fibrous substrate, which combines hot melt coatability with good adhesive performance. [Means for solving the problem]

[0006] According to this specification, a pressure-sensitive adhesive sheet is provided that includes a fibrous substrate and a pressure-sensitive adhesive layer laminated on the fibrous substrate. The pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer contains a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, a tackifying resin, and a plasticizer. The pressure-sensitive adhesive has a shear viscosity at 195°C (hereinafter sometimes simply referred to as shear viscosity) of 1300 Pa·s or more and 3000 Pa·s or less. The fibrous substrate has a basis weight of 30 g / m 2 The adhesive layer has a viscosity of 100 μm or less and a thickness of 60 μm or less. The residual organic solvent content in the adhesive layer is less than 1000 ppm. By combining an adhesive having the above shear viscosity with the above fibrous substrate, it is possible to realize a substantially solvent-free adhesive sheet having a residual organic solvent content of less than 1000 ppm, which combines hot melt coatability with good adhesive performance.

[0007] In some preferred embodiments, the PSA contains a tackifier resin (A1) having a softening point of 60°C or higher but lower than 120°C. The tackifier resin (A1), together with the plasticizer, can advantageously contribute to improving the hot-melt coatability of the PSA (e.g., reducing shear viscosity). In some embodiments, the weight ratio of the plasticizer content to the tackifier resin (A1) content (plasticizer / A1) is preferably greater than 0.060 but not greater than 0.200. PSA that satisfy this weight ratio can achieve both good cohesion and high levels of impregnation into fibrous substrates.

[0008] In some preferred embodiments, the total content of the tackifier resin (A1) and the plasticizer in the PSA is 70 parts by weight or more and less than 100 parts by weight per 100 parts by weight of the block copolymer. The technology disclosed herein can be suitably practiced using a PSA having a total content of the tackifier resin (A1) and the plasticizer in the above range.

[0009] In some embodiments, the PSA preferably comprises a tackifier resin (A1) having a softening point of 60°C or higher but lower than 120°C, and a tackifier resin (A3) having a softening point of 150°C or higher. Adjusting the shear viscosity to within the above-mentioned range while using the tackifier resin (A3) can be advantageous in terms of the PSA's holding power, repulsion resistance, etc. In some embodiments, the weight ratio of the total content of the tackifier resin (A1) and the plasticizer to the content of the tackifier resin (A3) in the PSA ((A1 + plasticizer) / A3) is preferably 3.5 or higher and 5.0 or lower. A composition that satisfies this weight ratio makes it easier to obtain a PSA having a shear viscosity within the above-mentioned range.

[0010] As the block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, for example, a styrene-based block copolymer can be preferably used. The technology disclosed herein can be suitably implemented using a PSA containing a styrene-based block copolymer, a tackifier resin, and a plasticizer. In some embodiments, the styrene-based block copolymer preferably has a styrene content of 10% by weight or more and 22% by weight or less. By combining a PSA containing such a styrene-based block copolymer with the above-mentioned fibrous substrate, a PSA sheet exhibiting good adhesive performance is likely to be obtained.

[0011] In some preferred embodiments, the content of the phenolic tackifier resin in the PSA layer is less than 1 part by weight per 100 parts by weight of the block copolymer. By limiting the amount of the phenolic tackifier resin used as described above, a PSA having good storage stability and excellent quality stability such as adhesive properties can be preferably obtained.

[0012] In some embodiments, the thickness of the PSA layer is preferably 40 μm or more and 200 μm or less. In a PSA sheet having a configuration in which a PSA layer of the above thickness is laminated on a fibrous substrate, the effects of the technology disclosed herein can be preferably realized.

[0013] The PSA sheet according to some embodiments has an adhesive strength of 20 N / 10 mm or more when measured under conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees in an environment of 23°C and 50% RH, and 2 The adhesive protrusion length measured under conditions of applying a 2 kg load to the adhesive sheet at a corner for 12 hours at 40°C is 100 μm or less. Having the adhesive protrusion length be a predetermined length or less is preferable from the viewpoints of improving the shape stability of the adhesive sheet and preventing blocking. According to the technology disclosed herein, in a form in which an adhesive layer is laminated on a fibrous substrate, it is possible to realize an adhesive sheet that exhibits high adhesive strength while suppressing the adhesive protrusion length as described above.

[0014] Appropriate combinations of the elements described in this specification may also be included within the scope of the invention for which patent protection is sought by this patent application. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic cross-sectional view showing the configuration of a pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet with a substrate) according to one embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the initial state of a test piece attached to an adherend in a repulsion resistance evaluation. [Figure 3] FIG. 2 is a schematic diagram showing a state in which an edge of a test piece attached to an adherend is lifted up from the adherend in a repulsion resistance evaluation. [Figure 4] FIG. 1 is a schematic explanatory view showing a method for testing anti-blocking properties. DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will be described below. Matters necessary for carrying out the present invention other than those specifically mentioned in this specification can be understood by those skilled in the art based on the teachings on carrying out the invention described in this specification and the common general technical knowledge at the time of filing. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the relevant field. In the following drawings, components and parts having the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. The embodiments shown in the drawings are schematic in order to clearly explain the present invention, and do not accurately represent the size or scale of the actual product.

[0017] As used herein, the term "adhesive" refers to a material that, as described above, is in a soft solid (viscoelastic) state at temperatures near room temperature and has the property of easily adhering to an adherend when pressure is applied. The adhesive in the technology disclosed herein can also be understood as the solid content of an adhesive composition or a constituent of an adhesive layer. The term "adhesive sheet" as used herein also encompasses what are known as adhesive tapes, adhesive labels, adhesive films, and the like. The adhesive sheets disclosed herein may be in the form of rolls or sheets. Alternatively, they may be adhesive sheets processed into various shapes.

[0018] In this specification, a "block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound" refers to a polymer having at least one segment (hereinafter also referred to as an "A segment") in which a monovinyl-substituted aromatic compound is the main monomer (meaning more than 50% by weight of the copolymerization component; the same applies hereinafter) and at least one segment (hereinafter also referred to as a "B segment") in which a conjugated diene compound is the main monomer. Generally, the glass transition temperature of the A segment is higher than the glass transition temperature of the B segment. Representative structures of such polymers include a triblock copolymer (ABA triblock copolymer) in which an A segment (hard segment) is attached to each end of a B segment (soft segment), and a diblock copolymer (AB diblock copolymer) consisting of one A segment and one B segment.

[0019] In this specification, the term "styrene-based block copolymer" refers to a polymer having at least one styrene block. The styrene block refers to a segment (hard segment) in which styrene is the main monomer. A typical example of the styrene block referred to here is a segment consisting essentially of styrene. Furthermore, the term "styrene-isoprene block copolymer" refers to a polymer having at least one styrene block and at least one isoprene block (a segment in which isoprene is the main monomer). Typical examples of styrene-isoprene block copolymers include a copolymer (triblock copolymer) with a triblock structure having styrene blocks (hard segments) on both ends of an isoprene block (soft segment), and a copolymer (diblock copolymer) with a diblock structure consisting of one isoprene block and one styrene block. The term "styrene-butadiene block copolymer" refers to a polymer having at least one styrene block and at least one butadiene block (a segment in which butadiene is the main monomer).

[0020] In this specification, the "styrene content" of a styrene-based block copolymer refers to the weight ratio of the styrene component to the total weight of the block copolymer. The styrene content can be measured by NMR (nuclear magnetic resonance spectroscopy). The proportion of diblock units in a styrene-based block copolymer (hereinafter sometimes referred to as the "diblock unit ratio" or "diblock ratio") is determined by the following method. Specifically, the styrene-based block copolymer is dissolved in tetrahydrofuran (THF), and high-performance liquid chromatography is performed using two liquid chromatography columns, each manufactured by Tosoh Corporation (GS5000H and G4000H), connected in series (a total of four columns, two columns each). The mobile phase is THF, and the temperature is 40°C and the flow rate is 1 mL / min. The peak area corresponding to the diblock unit is measured from the resulting chart. The diblock unit ratio is then determined by calculating the percentage of the peak area corresponding to the diblock unit relative to the total peak area.

[0021] In this specification, "weight" may be read as "mass." For example, "% by weight" may be read as "% by mass," and "parts by weight" may be read as "parts by mass."

[0022] <Adhesive sheet structure example> The PSA sheet disclosed herein (which may be in a long form such as a tape) may be in the form of, for example, a double-sided PSA sheet having the cross-sectional structure schematically shown in FIG. 1. This double-sided PSA sheet 1 comprises a fibrous base material 15, a first PSA layer 11 laminated on a first surface 15A of the fibrous base material 15, and a second PSA layer 12 laminated on a second surface 15B of the fibrous base material 15. Before use (before attachment to an adherend), the double-sided PSA sheet 1 may be in a spirally wound form, as shown in FIG. 1, for example, in which the front surface 21A and back surface 21B of the double-sided PSA sheet 1 are both release surfaces and are superimposed on a release liner 21. In such a double-sided PSA sheet 1, the surface of the second PSA layer 12 (second PSA surface 12A) is protected by the front surface 21A of the release liner 21, and the surface of the first PSA layer 11 (first PSA surface 11A) is protected by the back surface 21B of the release liner 21. Alternatively, the first adhesive surface 11A and the second adhesive surface 12A may each be protected by two independent release liners.

[0023] The adhesive sheet disclosed herein may also be in the form of a single-sided adhesive sheet comprising a fibrous substrate and an adhesive layer laminated on the first side thereof, with no adhesive layer on the second side of the fibrous substrate.

[0024] The release liner may be a conventional one and is not particularly limited. For example, a release liner having a release treatment layer on the surface of a plastic film (also called a release film), a release liner having a release treatment layer on the surface of paper (which may be paper with a plastic layer on its surface), or a release liner made of a low-adhesion material such as a fluorine-based polymer (polytetrafluoroethylene, etc.) or a polyolefin-based resin (polyethylene, polypropylene, etc.) may be used. The release treatment layer may be formed by surface treating the substrate with a release treatment agent such as a silicone-based, long-chain alkyl-based, fluorine-based, or molybdenum sulfide.

[0025] <Fiber base material> The pressure-sensitive adhesive sheet disclosed herein has a configuration in which a pressure-sensitive adhesive layer is laminated on a fibrous substrate. By using a fibrous material as the substrate, the pressure-sensitive adhesive sheet has good processability and handleability due to the substrate, while also having moderate flexibility, allowing it to conform well to the adherend and improve repulsion resistance. The fibrous substrate can be a woven fabric, nonwoven fabric, knitted fabric, net, etc., made by spinning various fibrous materials alone or in combination. The term "nonwoven fabric" as used herein encompasses nonwoven fabrics produced using a general papermaking machine, such as paper products such as Japanese paper and fine paper. Felt is also included in the concept of nonwoven fabric. Examples of the fibrous material constituting the fibrous substrate include natural fibers and chemical fibers (synthetic fibers) as described below, as well as inorganic fibers such as glass fibers and carbon fibers, and metal fibers. Two or more fibrous materials of different materials may be used in combination. The fibrous substrate can also be understood as a support substrate for supporting the pressure-sensitive adhesive layer.

[0026] As the fibrous substrate, a nonwoven fabric can be preferably used. Examples of the nonwoven fabric include nonwoven fabrics made of natural fibers such as pulps such as wood pulp and hemp pulp, cotton, hemp (e.g., Manila hemp), wool, and silk; nonwoven fabrics made of chemical fibers (synthetic fibers) such as polyester fibers such as polyethylene terephthalate (PET) fibers, rayon, vinylon, acetate fibers, polyvinyl alcohol (PVA) fibers, polyamide fibers, polyolefin fibers, and polyurethane fibers; and nonwoven fabrics made by combining two or more types of fibers made of different materials. Among these, from the viewpoint of adhesive impregnation and strength, nonwoven fabrics made of paper pulp such as wood pulp and hemp pulp (e.g., hemp pulp made from Manila hemp) are preferred.

[0027] The fibrous base material has a basis weight of 30 g / m 2A fibrous substrate that satisfies the above basis weight and thickness requirements and has a thickness of 60 μm or less is used. When combined with the adhesive disclosed herein, a fibrous substrate that satisfies the above basis weight and thickness requirements can easily achieve a good balance between improving the strength of the fibrous substrate itself and impregnating the adhesive into the interior of the fibrous substrate. This can be advantageous from the perspective of exerting high adhesive strength in an adhesive sheet formed by hot melt coating. Furthermore, by thoroughly impregnating the fibrous substrate with an adhesive layer, it is possible to suppress adhesive extrusion from the edge of the adhesive sheet (e.g., adhesive extrusion due to compressive stress applied in the thickness direction of the adhesive layer), thereby improving the adhesive's anti-blocking properties. Suppressing adhesive extrusion is also preferable from the perspective of improving the handleability and appearance of the adhesive sheet (e.g., preventing dust and the like from adhering to the extrusion area).

[0028] In some embodiments, the basis weight (weight per unit area) of the fibrous substrate is 27 g / m 2 It may be less than 25 g / m 2 or less (e.g. 25g / m 2 less than 23 g / m 2 It may be less than 22 g / m 2 It may be less than 20 g / m 2 In some preferred embodiments, the basis weight may be 18 g / m or less. 2 or less (e.g. 18g / m 2 less than 16 g / m 2 It may be less than 15 g / m 2 In some embodiments, the basis weight may be less than 10 g / m 2 It is preferable that the content is 12 g / m or more. 2 More preferably, it is 14 g / m or more. 2 It may be 16 g / m or more. 2 The fibrous substrate having the above basis weight tends to have a moderate strength. The technology disclosed herein can be more suitably implemented by selecting and using a fibrous substrate having a basis weight within the above range.

[0029] In some embodiments, the thickness of the fibrous substrate is advantageously 55 μm or less, preferably 50 μm or less, and may be 45 μm or less, 43 μm or less, or 40 μm or less. A smaller thickness of the fibrous substrate makes it easier to impregnate the interior of the fibrous substrate with the adhesive. In some embodiments, the thickness may be 10 μm or more, or 15 μm or more. In some preferred embodiments, the thickness is 20 μm or more, more preferably 25 μm or more, even more preferably 30 μm or more, and may be 35 μm or more, or even 40 μm or more. By increasing the thickness of the fibrous substrate within the above range, a good balance can be achieved between improving the strength of the fibrous substrate itself and impregnating the interior of the fibrous substrate with the adhesive.

[0030] Although not particularly limited, the density (bulk density) of the fibrous base material is 0.70 g / m 3 It is appropriate that the content is less than 0.60 g / m 3 Preferably, it is 0.50 g / m or less. 3 It is more preferable that the density of the fibrous substrate is not too high, which is advantageous from the viewpoint of impregnation of the fibrous substrate with the adhesive. 3 or more, and 3 It may be 0.25 g / cm or more. 3 In some embodiments, the density of the fibrous base material may be 0.30 g / cm or more. 3 or more (e.g., 0.30 g / cm 3 Preferably, it is greater than 0.31 g / cm 3 More than 0.32g / cm 3 or more than 0.33g / cm 3 More preferably, it is 0.35 g / cm or more. 3 It may be 0.40 g / cm or more. 3 More than 0.45g / cm 3The density of the fibrous base material is not too low, which can be advantageous from the viewpoint of preventing the fibrous base material from being easily crushed in the thickness direction during production of the adhesive sheet, making it difficult for the adhesive to be impregnated, and realizing an adhesive sheet in which the adhesive is well impregnated into the fibrous base material.

[0031] In addition to the fibrous materials described above, fibrous substrates (e.g., nonwoven fabrics) may contain resin components, typically in a non-fibrous form, such as starch (e.g., cationized starch), polyacrylamide, viscose, polyvinyl alcohol, urea-formaldehyde resin, melamine-formaldehyde resin, and polyamidepolyamine epichlorohydrin. The resin components may function as paper strength agents for nonwoven fabrics. By using such resin components as needed, the strength of the fibrous substrate and the impregnation of the adhesive into the fibrous substrate can be adjusted. The fibrous substrates of the technology disclosed herein may also contain, as needed, additives commonly used in the field of fibrous substrate (e.g., nonwoven fabric) manufacturing, such as retention aids, drainage aids, viscosity modifiers, and dispersants.

[0032] <Adhesive> (shear viscosity) The PSA sheet disclosed herein has a PSA layer laminated on the fibrous substrate, the PSA layer being composed of a PSA having a shear viscosity of 1300 Pa·s or more and 3000 Pa·s or less at 195°C. PSA with a shear viscosity of 3000 Pa·s or less can be formed by hot-melt coating, and tends to be easily impregnated into a fibrous substrate that satisfies the above-mentioned basis weight and thickness. Furthermore, a PSA with a shear viscosity of 1300 Pa·s or more is advantageous from the standpoint of the cohesive strength of the PSA (e.g., improved holding power, suppression of PSA extrusion, etc.). Therefore, by combining a PSA with the above-mentioned shear viscosity with the fibrous substrate, a PSA sheet that combines good hot-melt coating properties and excellent adhesive performance can be realized.

[0033] In this specification, the shear viscosity of the adhesive is measured using a commercially available rheometer viscometer at a measurement temperature of 195°C and a shear rate (shear rate) of 0.1 seconds.-1 The shear viscosity is measured under the following conditions. As the rheometer viscometer, for example, a rheometer viscometer (HAAKE RheoStress 6000) manufactured by Thermo Fisher Scientific or an equivalent product can be used. More specifically, the shear viscosity of the PSA is measured by the method described in the Examples below.

[0034] In some embodiments, from the viewpoint of hot melt coatability and the like, the shear viscosity of the PSA is preferably 2800 Pa·s or less, more preferably 2600 Pa·s or less, and may be 2500 Pa·s or less, 2400 Pa·s or less, or may be 2300 Pa·s or less. Furthermore, in some embodiments, from the viewpoint of easily obtaining good cohesive strength, the shear viscosity of the PSA is preferably 1500 Pa·s or more, more preferably 1700 Pa·s or more, and may be 1900 Pa·s or more, 2100 Pa·s or more, or may be 2200 Pa·s or more. The shear viscosity of the PSA can be adjusted by the composition of the PSA.

[0035] (Block copolymer) The PSA constituting the PSA layer disclosed herein (in embodiments having a first PSA layer and a second PSA layer, at least one of the PSA layers; the same applies hereinafter unless otherwise specified) contains a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound. Here, the monovinyl-substituted aromatic compound refers to a compound in which one vinyl-containing functional group is bonded to an aromatic ring. A representative example of the aromatic ring is a benzene ring (which may be a benzene ring substituted with a vinyl-free functional group (e.g., an alkyl group)). Specific examples of the monovinyl-substituted aromatic compound include styrene, α-methylstyrene, vinyltoluene, and vinylxylene. Specific examples of the conjugated diene compound include 1,3-butadiene and isoprene. Such block copolymers can be used alone or in combination of two or more.

[0036] The block copolymer of the monovinyl-substituted aromatic compound and the conjugated diene compound (for example, the styrene-based block copolymer described below) is a component that can be used as the base polymer of the PSA. Here, the "base polymer" of the PSA refers to the main component (i.e., the component that accounts for more than 50% by weight of the rubbery polymer) contained in the PSA (a polymer that exhibits rubber elasticity in a temperature range around room temperature).

[0037] In the block copolymer, the A segment (hard segment) preferably has a copolymerization ratio of the monovinyl-substituted aromatic compound (two or more types may be used in combination) of 70% by weight or more (more preferably 90% by weight or more, and may be substantially 100% by weight). In the block copolymer, the B segment (soft segment) preferably has a copolymerization ratio of the conjugated diene compound (two or more types may be used in combination) of 70% by weight or more (more preferably 90% by weight or more, and may be substantially 100% by weight). Such a block copolymer can realize a pressure-sensitive adhesive sheet with higher performance.

[0038] The block copolymer (e.g., styrene-based block copolymer) may be in the form of a diblock copolymer, a triblock copolymer, a radial copolymer, a mixture thereof, or the like. In the triblock copolymer or radial copolymer, it is preferable that an A segment (e.g., a styrene block) is disposed at the end of the polymer chain. This is because the A segments disposed at the end of the polymer chain tend to gather together to form domains, which form a pseudo-crosslinked structure and improve the cohesive strength of the PSA.

[0039] In the technology disclosed herein, a block copolymer (e.g., a styrene-based block copolymer) having a diblock ratio of 30% by weight or more is preferably used from the viewpoint of adhesive strength. The diblock ratio is more preferably 40% by weight or more, even more preferably 50% by weight or more, particularly preferably 60% by weight or more, even more particularly preferably 65% ​​by weight or more, and most preferably 70% by weight or more (e.g., 75% by weight or more). Furthermore, from the viewpoint of cohesion and the like, a block copolymer having a diblock ratio of 90% by weight or less (more preferably 85% by weight or less, e.g., 80% by weight or less) is preferably used. In order to better exert the effects of the technology disclosed herein, in some embodiments, a block copolymer (e.g., a styrene-based block copolymer) having a diblock ratio of 60 to 85% by weight is preferred, and a block copolymer having a diblock ratio of 70 to 85% by weight (e.g., more than 70% by weight but not more than 80% by weight) is more preferred. In an embodiment using two or more types of block copolymers (for example, two or more types of styrene-based block copolymers), the diblock proportion refers to the sum of the products of the weight fractions of each block copolymer in the total weight of the two or more types of block copolymers (100% by weight) and the diblock proportions of the block copolymers.

[0040] In some preferred embodiments, a styrene-based block copolymer is used as the block copolymer. In this specification, the term "styrene-based block copolymer" refers to a block copolymer of styrene and a conjugated diene compound. For example, a preferred embodiment is one in which the styrene-based block copolymer comprises at least one of a styrene-isoprene block copolymer and a styrene-butadiene block copolymer. The styrene-based block copolymer may comprise a hydrogenated product in which at least a portion of the styrene-based block copolymer has been hydrogenated (hydrogen atoms have been added). The styrene-based block copolymers may be used alone or in combination of two or more. Of the styrene-based block copolymers contained in the pressure-sensitive adhesive layer, it is preferred that the proportion of styrene-isoprene block copolymer is 70% by weight or more, the proportion of styrene-butadiene block copolymer is 70% by weight or more, or the combined proportion of the styrene-isoprene block copolymer and the styrene-butadiene block copolymer is 70% by weight or more. In some preferred embodiments, substantially all (e.g., 95 to 100% by weight) of the styrene-based block copolymer is a styrene-isoprene block copolymer. In some other preferred embodiments, substantially all (for example, 95 to 100% by weight) of the styrene-based block copolymer is a styrene-butadiene block copolymer. With such a composition, the effects of the technology disclosed herein can be preferably exhibited.

[0041] The styrene content of the styrene-based block copolymer may be, for example, 5 to 40% by weight. From the viewpoint of cohesion, the styrene content is preferably 10% by weight or more (e.g., more than 10% by weight), more preferably 12% by weight or more, and may be, for example, 14% by weight or more. From the viewpoint of flexibility, flowability, etc. of the PSA, the styrene content of the styrene-based block copolymer is preferably 35% by weight or less (typically 30% by weight or less, more preferably 25% by weight or less), and particularly preferably 22% by weight or less (typically less than 20% by weight, for example, 18% by weight or less). From the viewpoint of better exerting the effects of the technology disclosed herein, in some embodiments, a styrene-based block copolymer having a styrene content of 10% by weight or more and 22% by weight or less (e.g., 10% by weight or more and 18% by weight or less) can be preferably used. Note that in embodiments using two or more styrene-based block copolymers, the styrene content refers to the styrene content in the total amount (100% by weight) of the two or more styrene-based block copolymers.

[0042] (tackifying resin) The PSA disclosed herein contains a tackifier resin in addition to the block copolymer. The inclusion of a tackifier resin in a PSA can increase adhesive strength and adjust the shear viscosity of the PSA. One tackifier resin can be used alone, or two or more can be used in combination. The tackifier resin is not particularly limited, and for example, both petroleum-based and natural product-based tackifier resins can be used. Here, petroleum-based tackifier resins are compounds derived from petroleum resources, have a chemical structure derived from petroleum resources, and impart adhesive properties due to compatibility with PSAs and chemical properties based on that chemical structure. Natural product-based tackifier resins are compounds containing components derived from natural products, have a chemical structure derived from natural products, and impart adhesive properties due to compatibility with PSAs and chemical properties based on that chemical structure. In some preferred embodiments, PSAs that can optimally combine hot-melt coatability and good adhesive performance can be designed by appropriately selecting one or more petroleum-based and natural product-based tackifier resins based on their chemical structures.

[0043] Examples of petroleum-based tackifying resins include aliphatic (C5) petroleum resins, aromatic (C9) petroleum resins, aliphatic / aromatic copolymer (C5 / C9) petroleum resins, styrene-based resins, and hydrogenated versions of these (e.g., alicyclic petroleum resins obtained by hydrogenating aromatic petroleum resins). Other examples of petroleum-based tackifying resins include coumarone-indene resins and dicyclopentadiene resins. Petroleum-based tackifying resins can be used alone or in combination of two or more.

[0044] Examples of styrene-based resins include those containing a homopolymer of styrene as the main component, those containing a homopolymer of α-methylstyrene as the main component, those containing a homopolymer of vinyltoluene as the main component, and those containing a copolymer containing two or more of styrene, α-methylstyrene, and vinyltoluene as the main component in the monomer composition (for example, an α-methylstyrene / styrene copolymer resin containing an α-methylstyrene / styrene copolymer as the main component).

[0045] The coumarone-indene resin can be a resin containing coumarone and indene as monomer components that make up the resin skeleton (main chain). Other monomer components that can be included in the resin skeleton besides coumarone and indene include styrene, α-methylstyrene, methylindene, vinyltoluene, etc.

[0046] Examples of natural product-based tackifying resins include terpene resins and rosin-based resins. Terpene resins include unmodified terpene resins and modified terpene resins. Rosin-based resins include rosin derivative resins. Natural product-based tackifying resins can be used alone or in combination of two or more.

[0047] Examples of terpene resins (unmodified terpene resins) include α-pinene polymers, β-pinene polymers, dipentene polymers, etc. Examples of modified terpene resins include those obtained by modifying the above-mentioned terpene resins (phenol-modified, aromatic-modified (e.g., styrene-modified), hydrogenation-modified, hydrocarbon-modified, etc.). Specific examples include terpene phenolic resins, aromatic-modified (e.g., styrene-modified) terpene resins, and hydrogenated terpene resins. The above-mentioned terpene phenolic resins may include hydrogenated terpene phenolic resins.

[0048] The above-mentioned "terpene phenol resin" refers to a polymer containing a terpene residue and a phenol residue, and is a concept that encompasses both a copolymer of a terpene and a phenol compound (terpene-phenol copolymer resin) and a phenol-modified terpene homopolymer or copolymer (terpene resin, typically an unmodified terpene resin) modified with phenol.

[0049] Specific examples of rosin-based resins include unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; modified rosins (hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosins, etc.) obtained by modifying these unmodified rosins through hydrogenation, disproportionation, polymerization, etc.; etc. Examples of rosin derivative resins include rosin esters such as those obtained by esterifying unmodified rosin with alcohols (i.e., esterified rosin), and those obtained by esterifying modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) with alcohols (i.e., esterified modified rosin); unsaturated fatty acid modified rosins obtained by modifying unmodified rosin or modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.) with unsaturated fatty acid; and unsaturated fatty acid modified rosins obtained by modifying rosin esters with unsaturated fatty acid. Examples include rosin esters; rosin alcohols obtained by reducing the carboxyl groups of unmodified rosin, modified rosin (hydrogenated rosin, disproportionated rosin, polymerized rosin, etc.), unsaturated fatty acid modified rosins, or unsaturated fatty acid modified rosin esters; metal salts of rosins (particularly rosin esters) such as unmodified rosin, modified rosin, and various rosin derivatives; and rosin phenolic resins obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, etc.) using an acid catalyst and then thermally polymerizing the resulting mixture.

[0050] The softening point of the tackifier resin used in the technology disclosed herein is suitably 40°C, and is typically 60°C or higher. In some embodiments, from the viewpoint of improving the cohesive strength of the PSA, the softening point of the tackifier resin is preferably 80°C or higher (e.g., greater than 80°C), more preferably 100°C or higher (e.g., greater than 100°C), and may be 105°C or higher, or may be 110°C or higher. Furthermore, from the viewpoint of hot melt coatability, the softening point of the tackifier resin is suitably 200°C or lower, preferably 180°C or lower, more preferably 170°C or lower, and may be 160°C or lower, 140°C or lower, or 120°C or lower.

[0051] In this specification, the softening point of a tackifying resin is defined as a value measured using the softening point test method (ring and ball method) specified in JIS K5902 and JIS K2207. Specifically, the sample is melted as quickly as possible at the lowest possible temperature and carefully filled into a ring placed on a flat metal plate, avoiding the formation of bubbles. After cooling, any raised portion of the ring, including the top edge, is cut off using a slightly heated knife. Next, a holder (ring stand) is placed in a glass container (heating bath) with a diameter of at least 85 mm and a height of at least 127 mm, and glycerin is poured in to a depth of at least 90 mm. Next, a steel ball (9.5 mm diameter, 3.5 g weight) and the ring filled with the sample are immersed in the glycerin without touching each other, and the glycerin temperature is maintained at 20°C ± 5°C for 15 minutes. Next, the steel ball is placed in the center of the surface of the sample in the ring and placed in its fixed position on the holder. Next, place a thermometer at a distance of 50 mm from the top of the ring to the glycerin surface, aligning the center of the thermometer's mercury bulb with the center of the ring, and heat the container. The flame of the Bunsen burner used for heating should be aimed midway between the center of the bottom and the edge of the container, ensuring uniform heating. After heating begins and reaching 40°C, the bath temperature should increase at a rate of 5.0 ± 0.5°C per minute. The sample gradually softens, flows down the ring, and finally touches the bottom plate. This temperature is taken as the softening point. Two or more softening point measurements should be taken simultaneously, and the average value should be used. If the manufacturer provides a nominal softening point temperature, that nominal temperature may be used. If the nominal temperature has a range, the nominal temperature is calculated by dividing the range by two (top temperature + bottom temperature).

[0052] In some preferred embodiments, the tackifier resin comprises a tackifier resin (A1) having a softening point of 60°C or higher but lower than 120°C (more preferably, 80°C or higher but lower than 120°C). A tackifier resin having a softening point within the above temperature range can serve as a component that imparts appropriate fluidity to the PSA. For example, by using an appropriate amount of tackifier resin (A1) together with a plasticizer described below, it is possible to improve the hot-melt coatability of the PSA and its impregnation into fibrous substrates while suppressing excessive reduction in cohesive strength. The tackifier resin (A1) can be used alone or in combination of two or more. For example, one or more tackifier resins selected from terpene resins (e.g., unmodified terpene resins), rosin-based resins, petroleum-based tackifier resins, etc., having the appropriate softening point can be used as the tackifier resin (A1).

[0053] In embodiments using a tackifier resin (A1) as the tackifier resin, the content of the tackifier resin (A1) in the PSA may be, for example, 1 part by weight or more, 10 parts by weight or more, 20 parts by weight or more, or 30 parts by weight or more, relative to 100 parts by weight of the block copolymer. In some embodiments, from the viewpoint of effectively exerting the effect of adding the tackifier resin (A1), the content of the tackifier resin (A1) relative to 100 parts by weight of the block copolymer is suitably 35 parts by weight or more, preferably 40 parts by weight or more, or may be 45 parts by weight or more, 50 parts by weight or more, or may be 55 parts by weight or more. In some preferred embodiments, from the viewpoint of effectively imparting appropriate fluidity to the PSA while using an appropriate amount of tackifier resin (A3) described below, the content of the tackifier resin (A1) relative to 100 parts by weight of the block copolymer is more than 60 parts by weight, more preferably 65 parts by weight or more, or may be 68 parts by weight or more, 70 parts by weight or more, 72 parts by weight or more, or 75 parts by weight or more. In some embodiments, the content of the tackifier resin (A1) relative to 100 parts by weight of the block copolymer is suitably less than 120 parts by weight, and from the viewpoint of achieving both appropriate fluidity and cohesive strength, it is preferably less than 100 parts by weight, more preferably less than 90 parts by weight, and even more preferably less than 80 parts by weight.

[0054] In some preferred embodiments, the tackifier resin comprises a tackifier resin (A3) having a softening point of 150°C or higher (typically 150°C or higher and 200°C or lower, preferably 150°C or higher and 180°C or lower, more preferably 150°C or higher and 170°C or lower, for example, 155°C or higher and 170°C or lower). A tackifier resin having a softening point within the above temperature range can serve as a component that imparts appropriate cohesive strength to a PSA in a temperature range that is 20°C or higher (e.g., 30°C or higher, 50°C or higher, or 70°C or higher) lower than the softening point. The tackifier resin (A3) can be used alone or in combination of two or more. For example, one or more tackifier resins selected from rosin-based resins, petroleum-based tackifier resins, etc., having the corresponding softening point can be used as the tackifier resin (A3).

[0055] In embodiments using a tackifier resin (A3) as the tackifier resin, the content of the tackifier resin (A3) in the PSA may be, for example, 1 part by weight or more, or 5 parts by weight or more, per 100 parts by weight of the block copolymer. In some preferred embodiments, from the viewpoint of effectively utilizing the effects of using the tackifier resin (A3), the content of the tackifier resin (A3) per 100 parts by weight of the block copolymer is 10 parts by weight or more, 15 parts by weight or more, or even 20 parts by weight or more. In some embodiments, the content of the tackifier resin (A3) per 100 parts by weight of the block copolymer may be, for example, 80 parts by weight or less, 60 parts by weight or less, 50 parts by weight or less, or 40 parts by weight or less. In some preferred embodiments, from the viewpoint of the fluidity of the PSA, the content of the tackifier resin (A3) per 100 parts by weight of the block copolymer is suitably less than 40 parts by weight, advantageously less than 35 parts by weight, or may be 30 parts by weight or less, 25 parts by weight or less, or 20 parts by weight or less. In some other embodiments, the content of the tackifier resin (A3) relative to 100 parts by weight of the block copolymer may be 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less. The technology disclosed herein can be practiced in an embodiment using a PSA that is substantially free of tackifier resin (A3).

[0056] In some preferred embodiments, the tackifier resin comprises a tackifier resin (A1) and a tackifier resin (A3). The combined use of the tackifier resin (A1) and the tackifier resin (A3) can achieve a better balance between the fluidity and cohesive strength of the PSA. In such embodiments, the ratio of the tackifier resin (A1) to the tackifier resin (A3) used is not particularly limited. In some embodiments, the ratio (A1 / A3) of the content of the tackifier resin (A1) to the content of the tackifier resin (A3) is suitably greater than 1.0 by weight, advantageously greater than 2.0, preferably greater than 3.0 (e.g., 3.1 or greater), more preferably 3.3 or greater, and may even be 3.5 or greater, or 3.7 or greater. In some embodiments, the ratio (A1 / A3) is, for example, 10 or less, and may be 7.0 or less, and from the viewpoint of the fluidity of the adhesive, it is preferably less than 6.0, more preferably less than 5.0 or less than 4.5, and may be less than 4.3, less than 4.0, or less than 3.8.

[0057] In some preferred embodiments, the tackifier resin comprises a tackifier resin (A2) having a softening point of 140°C or higher (typically 140°C or higher and 200°C or lower, preferably 140°C or higher and 180°C or lower, more preferably 140°C or higher and 170°C or lower). A tackifier resin having a softening point within the above temperature range can serve as a component that imparts appropriate cohesive strength to a PSA in a temperature range that is 20°C or higher (e.g., 30°C or higher, 50°C or higher, or 70°C or higher) lower than the softening point. The tackifier resin (A2) can be used alone or in combination of two or more. For example, one or more tackifier resins selected from rosin-based resins, terpene resins, petroleum-based tackifier resins, etc., having the corresponding softening point can be used as the tackifier resin (A2).

[0058] In embodiments using tackifier resin (A2) as the tackifier resin, the content of tackifier resin (A2) in the PSA may be, for example, 1 part by weight or more, or 5 parts by weight or more, per 100 parts by weight of the block copolymer. In some preferred embodiments, from the viewpoint of effectively utilizing the effects of using tackifier resin (A2), the content of tackifier resin (A2) per 100 parts by weight of the block copolymer may be 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, or 40 parts by weight or more. Furthermore, the content of tackifier resin (A2) per 100 parts by weight of the block copolymer may be, for example, 80 parts by weight or less. From the viewpoint of the fluidity of the PSA, it is appropriate to use 60 parts by weight or less, preferably 50 parts by weight or less, and may be 45 parts by weight or less, or may be 40 parts by weight or less. Note that tackifier resin (A2) may also correspond to the above-mentioned tackifier resin (A3) depending on its softening point.

[0059] In some preferred embodiments, the tackifier resin comprises a tackifier resin (A1) and a tackifier resin (A2). The combined use of the tackifier resin (A1) and the tackifier resin (A2) allows for adjustment of the balance between the fluidity and cohesive strength of the PSA. In such embodiments, the ratio of the tackifier resin (A1) to the tackifier resin (A2) is not particularly limited. In some embodiments, the ratio (A2 / A1) of the content of the tackifier resin (A2) to the content of the tackifier resin (A1) is suitably 0.3 or greater, preferably 0.4 or greater, by weight. In some embodiments, the ratio (A2 / A1) is suitably 0.5 or greater, advantageously greater than 0.6 (e.g., greater than 0.65), preferably greater than 0.7 (e.g., greater than 0.75), and may even be 0.78 or greater, 0.8 or greater, or greater than 0.8 (e.g., greater than 0.85). In some embodiments, the ratio (A2 / A1) is suitably less than 2.0 (e.g., 1.9 or less) by weight, advantageously 1.5 or less or 1.3 or less, preferably less than 1.3, and more preferably less than 1.0 (e.g., less than 0.95).

[0060] The above description of the content and ratio (A2 / A1) of the tackifier resin (A2) is preferably applicable, for example, to an embodiment in which the content of the tackifier resin (A3) relative to 100 parts by weight of the block copolymer is 5 parts by weight or less (i.e., 0 to 5 parts by weight). By satisfying either or both of the content and ratio (A2 / A1) of the tackifier resin (A2), even in an embodiment in which the content of the tackifier resin (A3) is limited, the fluidity and cohesive strength of the PSA can be favorably achieved. Limiting the content of the tackifier resin (A3) can be advantageous from the viewpoint of the hot-melt coatability of the PSA.

[0061] In some preferred embodiments, the tackifier resin is one or more selected from the group consisting of unmodified terpene resins (hereinafter sometimes simply referred to as "terpene resins"), rosin-based resins, styrene-based resins, and aromatic petroleum resins. By selecting one or more appropriate tackifier resins from the above, a PSA that can achieve both hot-melt applicability and good adhesive performance is easily obtained. Among these, it is preferable to use at least a terpene resin as an essential component among terpene resins, rosin-based resins, and styrene-based resins. Furthermore, in addition to using a terpene resin as an essential component, it is more preferable to use at least one (preferably both) of a rosin-based resin and a styrene-based resin as an essential component. Alternatively, in addition to using a terpene resin as an essential component, a modified terpene resin (e.g., a terpene phenolic resin) may also be used as an essential component.

[0062] In some preferred embodiments, a terpene resin is used as the tackifier resin. Terpene resins are highly compatible with PSA containing the block copolymer, and their addition can be advantageously effective. While not intended to be limiting, terpene resins are highly compatible with the soft segments (segments containing a conjugated diene compound as the main monomer) of the block copolymer. Based on their softening point, they are believed to impart appropriate cohesive strength to the soft segments in a temperature range lower than the softening point of the terpene resin (e.g., a temperature range 10°C or more lower than the softening point, preferably a temperature range 20°C or more or 30°C or more lower than the softening point). Furthermore, based on their softening point, terpene resins can serve as a component that imparts appropriate fluidity to PSA. For example, the use of an appropriate amount of terpene resin can improve the PSA's hot-melt coatability and impregnation into fibrous substrates. Terpene resins can be used singly or in combination of two or more.

[0063] The softening point of the terpene resin may be, for example, within a range of about 40°C to 160°C. In some embodiments, the softening point of the terpene resin is suitably 60°C or higher, and from the viewpoint of cohesive strength, advantageously 80°C or higher (e.g., greater than 80°C), preferably 90°C or higher, more preferably 95°C or higher, even more preferably 100°C or higher (e.g., greater than 100°C), and particularly preferably 110°C or higher or greater than 110°C (e.g., 115°C or higher). Furthermore, from the viewpoint of improving the fluidity of the PSA, the softening point of the terpene resin is suitably less than 140°C, advantageously 130°C or lower, preferably 120°C or lower (e.g., less than 120°C), and may be 115°C or lower.

[0064] In embodiments using a terpene resin as a tackifier resin, the content of the terpene resin in the PSA may be, for example, 1 part by weight or more, 10 parts by weight or more, 20 parts by weight or more, or 30 parts by weight or more, relative to 100 parts by weight of the block copolymer. In some embodiments, from the viewpoint of effectively exerting the effect of adding the terpene resin, the content of the terpene resin relative to 100 parts by weight of the block copolymer is suitably 35 parts by weight or more, preferably 40 parts by weight or more, or may be 45 parts by weight or more, 50 parts by weight or more, or may be 55 parts by weight or more. In some preferred embodiments, from the viewpoint of effectively imparting appropriate fluidity to the PSA while using an appropriate amount of, for example, a rosin-based resin or a styrene-based resin described below, the content of the terpene resin relative to 100 parts by weight of the block copolymer is more than 60 parts by weight, more preferably 65 parts by weight or more, or may be 68 parts by weight or more, 70 parts by weight or more, 72 parts by weight or more, or may be 75 parts by weight or more. In some embodiments, the content of the terpene resin relative to 100 parts by weight of the block copolymer is suitably less than 120 parts by weight, and from the viewpoint of achieving both adequate fluidity and cohesive strength, it is preferably less than 100 parts by weight, more preferably less than 90 parts by weight, and even more preferably less than 80 parts by weight.

[0065] In embodiments using a terpene resin as a tackifier resin, the amount of the terpene resin relative to 1 part by weight of the soft segment (a segment having a conjugated diene compound as the main monomer) in the block copolymer is, for example, 0.10 parts by weight or more, preferably 0.20 parts by weight or more, or even 0.40 parts by weight or more, or even 0.50 parts by weight or more. In some preferred embodiments, the amount of the terpene resin relative to 1 part by weight of the soft segment of the block copolymer is 0.60 parts by weight or more, more preferably 0.75 parts by weight or more, even more preferably 0.80 parts by weight or more, and may even be more than 0.80 parts by weight (e.g., 0.85 parts by weight or more). In some embodiments, the amount of terpene resin per 1 part by weight of the soft segment of the block copolymer is suitably 1.5 parts by weight or less, and from the viewpoint of achieving both appropriate fluidity and cohesive strength, it is preferably 1.2 parts by weight or less, more preferably 1.0 part by weight or less, and may be less than 1.0 part by weight (for example, 0.95 parts by weight or less), 0.93 parts by weight or less, 0.90 parts by weight or less, 0.88 parts by weight or less, or 0.86 parts by weight or less. By setting the amount of terpene resin within the above range, the effect of adding the terpene resin can be effectively exerted based on the compatibility of the terpene resin with the soft segment.

[0066] In some preferred embodiments, a rosin-based resin is used as the tackifier resin. The rosin-based resin is highly compatible with the pressure-sensitive adhesive containing the block copolymer, and the effects of its addition can be suitably exhibited. Although not intended to be particularly limiting, the rosin-based resin usually has a high-polarity region and a low-polarity region in one molecule, and is compatible with each segment (hard segment and soft segment) of the block copolymer. It is thought that this contributes to improving adhesive properties based on a compatibility action different from that of terpene resins. The rosin-based resins can be used alone or in combination of two or more.

[0067] The softening point of the rosin-based resin may be, for example, within a range of about 40°C to 200°C. In some embodiments, the softening point of the rosin-based resin may be 60°C or higher, 80°C or higher (e.g., greater than 80°C), 100°C or higher, or 110°C or higher. In some preferred embodiments, from the viewpoint of cohesive strength, the softening point of the rosin-based resin is 120°C or higher, more preferably 130°C or higher, even more preferably 140°C or higher, and particularly preferably 150°C or higher or 155°C or higher (e.g., greater than 155°C or 160°C or higher). Furthermore, from the viewpoint of hot-melt coatability, the softening point of the rosin-based resin is advantageously 180°C or lower, and preferably 170°C or lower.

[0068] In embodiments using a rosin resin as the tackifier resin, the content of the rosin resin in the PSA layer may be, for example, 1 part by weight or more, or 5 parts by weight or more, per 100 parts by weight of the block copolymer. In some preferred embodiments, from the viewpoint of effectively utilizing the effects of the rosin resin, the content of the rosin resin per 100 parts by weight of the block copolymer may be, for example, 10 parts by weight or more, 15 parts by weight or more, or even 20 parts by weight or more. Furthermore, in some embodiments, the content of the rosin resin per 100 parts by weight of the block copolymer may be, for example, 80 parts by weight or less, 60 parts by weight or less, 50 parts by weight or less, or 40 parts by weight or less. In some preferred embodiments, from the viewpoint of PSA fluidity, the content of the rosin resin per 100 parts by weight of the block copolymer is suitably less than 40 parts by weight, advantageously less than 35 parts by weight, or may be 30 parts by weight or less, 25 parts by weight or less, or 20 parts by weight or less. In some other embodiments, the content of the rosin resin relative to 100 parts by weight of the block copolymer may be 10 parts by weight or less, 5 parts by weight or less, or 1 part by weight or less. The technology disclosed herein can be practiced in an embodiment using a PSA that is substantially free of rosin resin.

[0069] In this specification, the PSA being substantially free of a specific tackifying resin such as a rosin-based resin means that the tackifying resin is not intentionally added to the PSA, and the content of the tackifying resin is less than 0.1 parts by weight (e.g., 0 to 0.05 parts by weight) per 100 parts by weight of the block copolymer.

[0070] In some preferred embodiments, the tackifier resin comprises a terpene resin and a rosin-based resin. Using a terpene resin and a rosin-based resin in combination as the tackifier resin can achieve a better balance between the fluidity and cohesive strength of the PSA. In such embodiments, the ratio of the terpene resin to the rosin-based resin is not particularly limited. In some embodiments, the ratio (T / R) of the terpene resin (T) content to the rosin-based resin (R) content is suitably greater than 1.0 by weight, advantageously greater than 2.0, preferably greater than 3.0 (e.g., 3.1 or greater), more preferably 3.3 or greater, and may be 3.5 or greater, or even 3.7 or greater. In some embodiments, the ratio (T / R) is, for example, 10 or less, or may be 7.0 or less. From the viewpoint of the fluidity of the PSA, it is preferably less than 6.0, more preferably less than 5.0 or less than 4.5, and may be less than 4.3, 4.0, or 3.8.

[0071] The total amount of the terpene resin and rosin resin contained in the PSA layer is not particularly limited, and can be an appropriate amount to achieve the desired effect. In some embodiments, the total amount of the terpene resin and rosin resin is, for example, 40 parts by weight or more, advantageously 60 parts by weight or more, preferably 70 parts by weight or more, more preferably 80 parts by weight or more, and even more preferably more than 80 parts by weight (e.g., 82 parts by weight or more), and may be 85 parts by weight or more, 90 parts by weight or more, 92 parts by weight or more, or 95 parts by weight or more, relative to 100 parts by weight of the block copolymer. Furthermore, the total amount of the terpene resin and rosin resin relative to 100 parts by weight of the block copolymer is suitably 140 parts by weight or less, preferably 120 parts by weight or less (e.g., less than 120 parts by weight), more preferably 110 parts by weight or less, and even more preferably less than 110 parts by weight, and may be less than 105 parts by weight, less than 100 parts by weight, or less than 97 parts by weight. By appropriately setting the amounts of the terpene resin and rosin resin used within the above ranges, it is possible to preferably obtain a pressure-sensitive adhesive that has a good balance between the fluidity and cohesive strength of the pressure-sensitive adhesive.

[0072] In some embodiments, the tackifier resin includes a styrene-based resin. By using an appropriate amount of styrene-based resin, the styrene-based resin is well compatible with a pressure-sensitive adhesive containing a block copolymer (e.g., a styrene-based block copolymer) of a monovinyl-substituted aromatic compound and a conjugated diene compound, and the effects of adding the styrene-based resin can be favorably exhibited. The use of a styrene-based resin can exhibit the effect of improving adhesive strength due to its structure containing an aromatic ring. Furthermore, the use of a styrene-based resin facilitates obtaining high cohesive strength. While not intended to be particularly limiting, styrene-based resins, because of their aromatic rings derived from styrene, are easily compatible with domains formed by the aggregation of hard segments of the block copolymer (hereinafter referred to as "hard domains"; in embodiments where the main component of the monovinyl-substituted aromatic compound is styrene, they are also referred to as "styrene domains"). For example, by the compatibility of a styrene-based resin having a predetermined softening point with a hard domain, the properties based on the pseudo-crosslinking caused by the hard domain are adjusted, which is thought to effectively contribute to, for example, improving adhesive strength and cohesive strength. One type of styrene-based resin can be used alone, or two or more types can be used in combination.

[0073] In some embodiments, the softening point of the styrene-based tackifier resin is greater than 100°C. From the viewpoint of improving cohesive strength, the softening point of the styrene-based tackifier resin is suitably 110°C or higher, preferably 125°C or higher, more preferably 135°C or higher, and may be greater than 135°C or 140°C or higher. The upper limit of the softening point of the styrene-based tackifier resin is not particularly limited, and is usually suitably 200°C or lower, may be 180°C or lower, may be 160°C or lower, or may be 150°C or lower. From the viewpoint of the fluidity of the PSA (e.g., hot-melt coatability), etc., it is preferably less than 150°C, more preferably less than 145°C, and may be 140°C or lower.

[0074] The content of the styrene-based tackifier resin in the PSA is not particularly limited, and an appropriate amount can be adopted to achieve the desired effect. In some embodiments, the content of the styrene-based tackifier resin is less than 40 parts by weight, and may be 35 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, 15 parts by weight or less, or 10 parts by weight or less, relative to 100 parts by weight of the block copolymer. In some preferred embodiments, the content of the styrene-based tackifier resin in the PSA layer is less than 10 parts by weight (e.g., 0 parts by weight or more and less than 10 parts by weight), may be 9 parts by weight or less, or may be 8 parts by weight or less, relative to 100 parts by weight of the block copolymer, from the viewpoint of achieving a good balance between the fluidity and cohesive strength of the PSA. Furthermore, in some embodiments, the content of the styrene-based tackifier resin relative to 100 parts by weight of the block copolymer is preferably 3 parts by weight or more, or 5 parts by weight or more, and may be more than 5 parts by weight or 7 parts by weight or more, from the viewpoint of easily achieving the effects of using the styrene-based tackifier resin. In some other embodiments, from the viewpoint of the flexibility and flowability of the PSA, the content of the styrene-based tackifying resin relative to 100 parts by weight of the block copolymer may be less than 3 parts by weight or less than 1 part by weight, and the PSA layer may be substantially free of the styrene-based tackifying resin.

[0075] Although not particularly limited, in some embodiments, the amount of styrene-based tackifier resin per part by weight of the hard segment (e.g., styrene component) in the block copolymer may be, for example, 1.5 parts by weight or less, or even 1.0 part by weight or less. From the viewpoint of the fluidity of the PSA, it is advantageous to be 0.8 parts by weight or less, preferably 0.7 parts by weight or less (e.g., 0.65 parts by weight or less), and more preferably 0.6 parts by weight or less (e.g., 0.55 parts by weight or less). The amount of styrene-based tackifier resin per part by weight of the hard segment (specifically, styrene component) of the block copolymer may be 0 parts by weight or more, for example, 0.01 parts by weight or more, 0.05 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, or 0.3 parts by weight or more. In some embodiments, from the viewpoint of better exerting the effect of adding the styrene-based tackifier resin, the amount of the styrene-based tackifier resin relative to 1 part by weight of the hard segment (specifically, the styrene component) of the block copolymer is preferably 0.35 parts by weight or more, more preferably 0.4 parts by weight or more, or may be 0.45 parts by weight or more, or may be 0.5 parts by weight or more.

[0076] In some embodiments, the tackifier resin comprises an aromatic petroleum resin. Aromatic petroleum resins are resins known as C9 petroleum resins and are understood to have a different chemical structure from the styrene-based tackifier resins described above. Aromatic petroleum resins are highly compatible with PSA containing the block copolymer, and the effects of adding them can be favorably exhibited. Furthermore, the use of aromatic petroleum resins makes it easier to obtain a moderate cohesive strength due to their chemical structure containing aromatic rings. While not intended to be particularly limiting, aromatic petroleum resins, because of their aromatic rings, are easily compatible with the hard domains (specifically, styrene domains) of the block copolymer. For example, when an aromatic petroleum resin having a predetermined softening point is compatible with the hard domains, the properties based on the pseudo-crosslinking caused by the hard domains are adjusted, which is thought to contribute to, for example, improving the cohesive strength of the PSA. Aromatic petroleum resins can be used alone or in combination of two or more.

[0077] In some embodiments, the softening point of the aromatic petroleum resin is greater than 100°C. From the viewpoint of improving cohesive strength, the softening point of the aromatic petroleum resin is suitably 110°C or higher, preferably 125°C or higher, more preferably 135°C or higher, and even more preferably 150°C or higher. The upper limit of the softening point of the aromatic petroleum resin is not particularly limited, and is usually suitably 200°C or lower. From the viewpoint of rough surface adhesion, etc., it is preferably 180°C or lower, more preferably 170°C or lower (for example, 160°C or lower), and may be 150°C or lower, or 140°C or lower.

[0078] In embodiments using an aromatic petroleum resin, the content of the aromatic petroleum resin in the PSA is not particularly limited and can be an appropriate amount to achieve the desired effect. In some embodiments, the content of the aromatic petroleum resin may be greater than 0 parts by weight, for example, 1 part by weight or more, 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, or 35 parts by weight or more (e.g., 40 parts by weight or more), per 100 parts by weight of the block copolymer. In some embodiments, the content of the aromatic petroleum resin per 100 parts by weight of the block copolymer is 70 parts by weight or less, 60 parts by weight or less, 50 parts by weight or less, 40 parts by weight or less, or 20 parts by weight or less. From the viewpoint of PSA fluidity, it may be 10 parts by weight or less, or 1 part by weight or less. The technology disclosed herein can be implemented in an embodiment using a PSA that is substantially free of aromatic petroleum resin.

[0079] Although not particularly limited, in some embodiments, the amount of aromatic petroleum resin per 1 part by weight of the hard segment (e.g., styrene component) in the block copolymer is suitably 10 parts by weight or less, and from the viewpoint of the fluidity of the PSA, it may be 5 parts by weight or less, 4 parts by weight or less, or 3 parts by weight or less. In some embodiments, the amount of aromatic petroleum resin per 1 part by weight of the hard segment (e.g., styrene component) of the block copolymer may be 0 parts by weight or more, and from the viewpoint of exerting the effect of adding the aromatic petroleum resin, it may be, for example, 0.01 parts by weight or more, 0.1 parts by weight or more, 0.5 parts by weight or more, 1 part by weight or more, or 1.5 parts by weight or more.

[0080] Although not particularly limited, the combined amount of tackifier resins (terpene resin, rosin resin, styrene resin, and aromatic petroleum resin) in the total amount of tackifier resins contained in the PSA is preferably greater than 50% by weight. By employing such a tackifier resin composition, the effects of the technology disclosed herein are favorably exhibited. According to the technology disclosed herein, a PSA with excellent adhesion to polar rough surfaces and non-polar surfaces can be formed without relying on tackifier resins other than the terpene resin, rosin resin, styrene resin, and aromatic petroleum resin (in other words, without requiring these as essential components). From this perspective, the combined amount of the terpene resin, rosin resin, styrene resin, and aromatic petroleum resin in the total amount of tackifier resin is more preferably 70% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more (e.g., 99 to 100% by weight).

[0081] In addition, the total amount of the terpene resin, rosin resin, styrene resin, and aromatic petroleum resin as the tackifier resin contained in the PSA is not particularly limited, and can be an appropriate amount to achieve the desired effect. In some embodiments, the total amount of the terpene resin, rosin resin, styrene resin, and aromatic petroleum resin is suitably 50 parts by weight or more relative to 100 parts by weight of the block copolymer, and may be 60 parts by weight or more, 65 parts by weight or more, preferably 70 parts by weight or more, more preferably 75 parts by weight or more, even more preferably 80 parts by weight or more, 90 parts by weight or more, 100 parts by weight or more, 110 parts by weight or more, or 120 parts by weight or more. In some embodiments, the total amount of the terpene resin, rosin resin, styrene resin, and aromatic petroleum resin per 100 parts by weight of the block copolymer is less than 180 parts by weight, may be 170 parts by weight or less, may be 150 parts by weight or less, preferably 140 parts by weight or less, more preferably 120 parts by weight or less, even more preferably 100 parts by weight or less (e.g., less than 100 parts by weight), particularly preferably 95 parts by weight or less, may be 90 parts by weight or less. By appropriately setting the amounts of the terpene resin, rosin resin, styrene resin, and aromatic petroleum resin used within the above ranges, a pressure-sensitive adhesive that can achieve a good balance between fluidity (e.g., hot-melt coatability and impregnation into fibrous substrates) and cohesive strength can be preferably obtained.

[0082] The pressure-sensitive adhesive layer may further contain a tackifying resin (other tackifying resin) other than unmodified terpene resin, rosin resin, styrene resin, and aromatic petroleum resin, to the extent that the effects of the present invention are not impaired. Examples of such other tackifying resins include aromatic modified terpene resin, terpene phenol resin, and rosin phenol resin. These are natural product-based tackifying resins containing an aromatic ring. Other examples of such other tackifying resins include aliphatic (C5) petroleum resins and alicyclic petroleum resins. These are petroleum-based tackifying resins that do not contain an aromatic ring.

[0083] Furthermore, although not particularly limited, the technology disclosed herein can achieve both hot melt coatability and good adhesive performance without relying on a phenolic tackifier resin (e.g., terpene phenol resin). While phenolic tackifier resins can contribute to improved adhesive properties, they are also prone to accelerating the deterioration of PSA. Therefore, this configuration allows a PSA with desired adhesive properties to be realized in a form with long-term quality stability. From this perspective, the content of the phenolic tackifier resin can be less than 30 wt %, or alternatively less than 10 wt %, or even less than 3 wt %, of the total amount of tackifier resin contained in the PSA layer. The technology disclosed herein can be implemented in an embodiment in which the PSA layer is substantially free of a phenolic tackifier resin. Furthermore, the content of the phenolic tackifier resin in the PSA layer is preferably less than 30 parts by weight, more preferably less than 10 parts by weight, even more preferably less than 3 parts by weight, and particularly preferably less than 1 part by weight, relative to 100 parts by weight of the block copolymer. By limiting the amount of phenolic tackifier resin used as described above, it is possible to preferably obtain a PSA that has good storage stability and excellent quality stability in adhesive properties, etc. The phenolic tackifier resin referred to here means a tackifier resin having a molecular structure containing a phenol skeleton, and is a concept that encompasses terpene phenolic resins, hydrogenated terpene phenolic resins, phenolic resins (alkylphenolic resins, xylene-formaldehyde resins, etc.), rosin phenolic resins, etc.

[0084] The total amount of tackifier resin in the PSA is not particularly limited and can be an appropriate amount to achieve the desired effect. In some embodiments, the total amount of tackifier resin is greater than 35 parts by weight, may be 45 parts by weight or more, suitably 50 parts by weight or more, may be 60 parts by weight or more, or may be 65 parts by weight or more, per 100 parts by weight of the block copolymer. In some preferred embodiments, the total amount of tackifier resin is 70 parts by weight or more, more preferably 75 parts by weight or more, even more preferably 80 parts by weight or more, may be 90 parts by weight or more, may be 100 parts by weight or more, or may be 105 parts by weight or more, per 100 parts by weight of the block copolymer. In some embodiments, the total amount of tackifier resin is less than 180 parts by weight, may be 170 parts by weight or less, or may be 160 parts by weight or less (e.g., 150 parts by weight or less), per 100 parts by weight of the block copolymer. In some preferred embodiments, the total amount of tackifier resin is 140 parts by weight or less, more preferably 130 parts by weight or less, or may be 120 parts by weight or less, or may be 110 parts by weight or less, relative to 100 parts by weight of the block copolymer. By keeping the total amount of tackifier resin used within the above range, it is easy to obtain a PSA sheet that exhibits good adhesive performance in hot melt coating.

[0085] (plasticizer) The PSA layer disclosed herein further contains a plasticizer in addition to the block copolymer and tackifying resin. The use of a plasticizer can improve the fluidity of the PSA (e.g., hot-melt coating properties, impregnation into fibrous substrates, etc.). Here, the term "plasticizer" as used herein refers to a fluid that is liquid or viscous at room temperature (e.g., 25°C) or a material with a softening point of 40°C or lower. The softening point can be measured using a method similar to that used to measure the softening point of the tackifying resin.

[0086] The type of plasticizer is not particularly limited, and an appropriate one is selected from those that can improve the fluidity of the adhesive (for example, reduce the shear viscosity) depending on the adhesive composition (the type of block copolymer and the type of tackifier resin). Examples of plasticizers include process oils such as paraffinic oil and naphthenic oil; liquid rubbers such as polybutene and polyisoprene; and the like. Liquid resins such as liquid terpene resin and liquid rosin resin may also be used as the plasticizer. Other examples of plasticizers include esters of higher fatty acids such as stearic acid and palmitic acid (higher fatty acid esters), and fatty acid amides. Among these, process oils are preferred. One type of plasticizer can be used alone, or two or more types can be used in combination.

[0087] The content of the plasticizer (e.g., process oil) in the PSA layer is not particularly limited, and an appropriate amount can be employed to achieve the desired effect. The content of the plasticizer may be greater than 0 parts by weight, for example, 1 part by weight or more, 2 parts by weight or more, or 3 parts by weight or more, per 100 parts by weight of the block copolymer. From the viewpoint of achieving a higher effect in use, in some embodiments, the content of the plasticizer per 100 parts by weight of the block copolymer may be 4 parts by weight or more (e.g., more than 4 parts by weight), 5 parts by weight or more, 7 parts by weight or more, 8 parts by weight or more, or 10 parts by weight or more. In some embodiments, the amount of plasticizer used per 100 parts by weight of the block copolymer is suitably less than 20 parts by weight, preferably less than 15 parts by weight, and may be less than 13 parts by weight or less than 10 parts by weight (e.g., 9 parts by weight or less). By limiting the amount of plasticizer used in this way and adjusting the adhesive composition (e.g., the type of tackifier resin) so as to obtain the desired shear viscosity described above, it is possible to preferably realize an adhesive sheet that exhibits good cohesive strength in hot melt coating.

[0088] In some embodiments, the PSA constituting the PSA layer suitably has a weight ratio of the content of the plasticizer to the content of the tackifying resin (A1) (plasticizer / A1) of less than 0.300. From the viewpoint of cohesive strength of adhesive force, it is advantageous to have it be less than 0.250, preferably 0.200 or less (e.g., less than 0.200), more preferably less than 0.170 (e.g., 0.160 or less), and may be 0.150 or less, or may be 0.140 or less. Furthermore, from the viewpoint of impregnation into the fibrous substrate, in some embodiments, the ratio (plasticizer / A1) is suitably greater than 0.050, advantageously greater than 0.060 or greater than 0.070. In some embodiments, the ratio (plasticizer / A1) is suitably greater than 0.080, preferably greater than 0.090, more preferably 0.100 or greater (e.g., greater than 0.100), and may be 0.110 or greater, or may be 0.130 or greater. It is also preferable that the above ratio (plasticizer / A1) is not too large from the viewpoint of preventing blocking of the adhesive.

[0089] Although not particularly limited, the total content of the tackifier resin (A1) and the plasticizer (hereinafter also referred to as "the amount of A1 + plasticizer") relative to 100 parts by weight of the block copolymer is suitably more than 40 parts by weight, advantageously 45 parts by weight or more, and preferably 50 parts by weight or more, from the viewpoint of hot melt coatability and the like. In some embodiments in which the PSA contains a tackifier resin (A3), the amount of A1 + plasticizer relative to 100 parts by weight of the block copolymer is preferably 60 parts by weight or more, advantageously 70 parts by weight or more, from the viewpoint of hot melt coatability and the like in such embodiments. Parts or more (e.g., more than 70 parts by weight) are more preferred, and it may be 75 parts by weight or more, or even 80 parts by weight or more. Furthermore, the amount of A1+plasticizer per 100 parts by weight of the block copolymer may be, for example, 150 parts by weight or less, and from the viewpoint of the cohesive strength of the PSA, it is advantageous to be 120 parts by weight or less, and is preferably 110 parts by weight or less (e.g., less than 110 parts by weight), more preferably 105 parts or less, 100 parts by weight or less, or 110 parts by weight or less, and may be 95 parts by weight or less, 90 parts by weight or less, or 85 parts by weight or less.

[0090] In some embodiments in which the PSA contains a tackifier resin (A3), the ratio of the total content of the tackifier resin (A1) and the plasticizer to the content of the tackifier resin (A3) ((A1 + plasticizer) / A3) is suitably 3.0 or more, advantageously 3.3 or more (e.g., 3.4 or more or 3.5 or more), preferably greater than 3.5 (e.g., 3.6 or more), more preferably 3.8 or more, may be 4.0 or more, or may be 4.2 or more. From the same viewpoint, the ratio ((A1 + plasticizer) / A3) is suitably 6.0 or less, preferably 5.5 or less (e.g., less than 5.5), more preferably 5.0 or less, may be less than 5.0, may be 4.8 or less, may be 4.6 or less, 4.5 or less, or may be 4.4 or less.

[0091] (anti-aging agent) The adhesive layer disclosed herein may contain an antioxidant, if necessary. The use of an antioxidant can improve the quality stability of the adhesive. Antiaging agents may be used alone or in combination of two or more. Examples of antioxidants include phosphorus-based antioxidants, phenol-based antioxidants (e.g., hindered phenol-based antioxidants), hindered amine-based antioxidants, aromatic amine-based antioxidants, and sulfur-based antioxidants. While not particularly limited, the amount of antioxidant contained in the adhesive layer disclosed herein may be, for example, approximately 20 parts by weight or less, typically 10 parts by weight or less, and may even be 5 parts by weight or less, per 100 parts by weight of the block copolymer. Furthermore, the amount of antioxidant may be, for example, 0.1 parts by weight or more, or may even be 0.5 parts by weight or more, or 1 part by weight or more, per 100 parts by weight of the block copolymer.

[0092] (Isocyanate compounds) The PSA disclosed herein may further contain an isocyanate compound. The use of an isocyanate compound can improve the cohesive strength of the PSA. A preferred isocyanate compound is a polyfunctional isocyanate (a compound having an average of two or more isocyanate groups per molecule, including those having an isocyanurate structure). One or more polyfunctional isocyanates selected from various isocyanate compounds (polyisocyanates) having two or more isocyanate groups per molecule can be used as the polyfunctional isocyanate. Examples of such polyfunctional isocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates. When an isocyanate compound is used, the amount used is not particularly limited, but can be, for example, more than 0 part by weight and not more than 10 parts by weight (typically 0.01 to 10 parts by weight) relative to 100 parts by weight of the block copolymer, or can be 0.1 to 10 parts by weight, or can be 0.1 to 5 parts by weight (typically 0.3 to 3 parts by weight, e.g., 0.5 to 1 part by weight). Furthermore, in some embodiments, the pressure-sensitive adhesive may be substantially free of an isocyanate compound from the viewpoint of hot-melt coating properties. Note that "the pressure-sensitive adhesive layer is substantially free of an isocyanate compound" means that the content of the isocyanate compound in the pressure-sensitive adhesive layer is less than 0.1% by weight (e.g., 0 to 0.05% by weight).

[0093] (Other ingredients) The adhesive constituting the adhesive layer disclosed herein may contain, as necessary, various additives commonly used in the field of adhesives, such as leveling agents, crosslinking agents, crosslinking aids, fillers, colorants (pigments, dyes, etc.), antistatic agents, UV absorbers, and light stabilizers. These various additives may be conventionally known and used in the usual manner. The adhesive disclosed herein may also contain one or more rubbery polymers other than the block copolymer, to the extent that the effects of the present invention are not impaired. The technology disclosed herein is preferably implemented in an embodiment in which the adhesive layer substantially does not contain rubbery polymers other than the block copolymer (e.g., a styrene-based block copolymer) (e.g., an embodiment in which the content is 0 to 1 part by weight per 100 parts by weight of the block copolymer).

[0094] In some embodiments, the PSA may be substantially free of a chelate compound. Here, the chelate compound refers to, for example, a chelate compound of an alkaline earth metal oxide and a resin (such as an alkylphenol resin) having a functional group (such as a hydroxyl group or a methylol group) to which the oxide can be coordinated. From the viewpoint of hot-melt coating properties of the PSA, the technology disclosed herein is preferably implemented in an embodiment in which the PSA does not contain any chelate compound at all, or the chelate compound content is 1 wt % or less.

[0095] In some preferred embodiments, the PSA may have a composition in which the combined amount of the block copolymer, tackifier resin, and plasticizer accounts for more than 50 wt % (e.g., 70 wt % or more, or even 80 wt % or more) of the total weight of the PSA (i.e., the weight of the PSA layer constituted by this PSA). The effects of the technology disclosed herein are preferably achieved in embodiments including a PSA layer having such a composition. In some preferred embodiments, the combined amount of the block copolymer, tackifier resin, and plasticizer in the entire PSA is 90 wt % or more, or may be 95 wt % or more (e.g., 95 to 100 wt %), 98 wt % or more (e.g., 98 to 100 wt %), or 99 wt % or more (e.g., 99 to 100 wt %). Furthermore, the upper limit of the combined amount of the block copolymer, tackifier resin, and plasticizer in the entire PSA may be 99.8 wt % or less, 99.5 wt % or less, or 99 wt % or less, in consideration of the addition of other components such as antioxidants.

[0096] The PSA layer disclosed herein may be formed from a PSA composition that is substantially free of organic solvents. Here, "the PSA composition is substantially free of organic solvents" means that the amount of organic solvent in the PSA composition is less than 1% by weight (e.g., less than 0.1% by weight). Such a PSA composition may be a hot-melt PSA composition. Hot-melt PSA compositions are preferable from the viewpoints of productivity and reducing environmental impact, since they can be applied in a heat-molten state that is substantially free of organic solvents.

[0097] The PSA layer may have a residual organic solvent content of less than 1000 ppm (less than 1000 μg of organic solvent per 1 g of PSA (i.e., less than 1000 μg / 1 g of PSA)). In some embodiments, the residual organic solvent content in the PSA layer may be, for example, less than 900 ppm, less than 800 ppm, less than 700 ppm, or less than 600 ppm; in some preferred embodiments, it may be less than 500 ppm, less than 400 ppm, less than 300 ppm, less than 200 ppm, or less than 100 ppm. In some embodiments, the residual organic solvent content in the PSA layer may be, for example, less than 90 ppm, less than 80 ppm, less than 70 ppm, less than 60 ppm, less than 50 ppm, less than 40 ppm, less than 30 ppm, less than 20 ppm, or less than 10 ppm. Such a PSA with a small amount of residual organic solvent is also preferred from the viewpoint of reducing environmental impact. The PSA layer having an amount of residual organic solvent less than a predetermined value can be formed from a substantially solvent-free PSA composition (typically, a hot-melt PSA composition). Therefore, in this specification, a PSA (layer) having an amount of residual organic solvent less than 1000 ppm can be rephrased as a solvent-free PSA (layer) or even a hot-melt PSA (layer). The amount of residual organic solvent in the PSA layer is specifically measured by the method described in the Examples below.

[0098] (Adhesive layer forming method) The method for forming a pressure-sensitive adhesive layer from a pressure-sensitive adhesive composition is not particularly limited, and any known appropriate method can be used. The pressure-sensitive adhesive composition disclosed herein can be molded by, for example, a calendar method, a casting method, an inflation extrusion method, a T-die extrusion method, or the like. In some preferred embodiments, a hot-melt coating method is used to form the pressure-sensitive adhesive layer. For example, it is preferable to coat a pressure-sensitive adhesive prepared (prepared) using a twin-screw extruder by a hot-melt coating method.

[0099] An example of a hot-melt coating method applied in the technology disclosed herein will be described below. When a pressure-sensitive adhesive composition is formed into a film by melt extrusion using the hot-melt coating method, the pressure-sensitive adhesive composition is heated to a relatively high temperature (specifically, 100°C or higher, e.g., 150 to 220°C) to form a highly fluid molten state. Next, the heated, molten pressure-sensitive adhesive composition is extruded from the die of the extruder of a hot-melt coating device at an appropriate speed (coating speed) and coated. The temperature during coating is generally approximately the same as the temperature during melting. The extruder is not particularly limited, and a known twin-screw extruder is preferably used, for example. The pressure-sensitive adhesive composition extruded from the die is continuously coated onto a film (substrate or release liner) on a back roll. The back roll, also known as a coating roll, is disposed on the opposite side (non-coated side) of the film to be coated and has the function of feeding the film. In this way, the pressure-sensitive adhesive composition is formed into a layer (also referred to as a film). The pressure-sensitive adhesive composition formed into a layer may be further cured by a crosslinking treatment such as irradiation with active energy rays such as ultraviolet rays. In this way, a pressure-sensitive adhesive layer is formed. The pressure-sensitive adhesive composition formed into a layer may be aged by storing it under appropriate temperature conditions (for example, approximately 30 to 50°C) for a certain period of time or more (for example, 12 hours or more), if necessary. A pressure-sensitive adhesive formed by the above-mentioned hot-melt coating is also called a hot-melt pressure-sensitive adhesive. The hot-melt coating device equipped with the extruder may be equipped with a feeder for mixing the pressure-sensitive adhesive composition, a gear pump, a back roll, a crosslinking treatment section for performing the above-mentioned crosslinking treatment, and other mechanisms (such as a filter or a degassing vent). Furthermore, a temperature-controllable roll (also called a heating roll) is preferably used as the back roll.

[0100] (Adhesive layer thickness) Although not particularly limited, the thickness of the pressure-sensitive adhesive layer may be approximately 20 μm or more, and from the viewpoints of hot-melt coating properties and impregnation into a fibrous substrate, it is preferably 30 μm or more, more preferably 40 μm or more, and may be 60 μm or more. In some preferred embodiments, from the viewpoints of adhesive strength and impact absorption, the thickness of the pressure-sensitive adhesive layer may be 80 μm or more, 100 μm or more (e.g., more than 100 μm), 120 μm or more, or 140 μm or more. Furthermore, the thickness of the pressure-sensitive adhesive layer may be, for example, approximately 1000 μm or less, 750 μm or less, 500 μm or less, or 400 μm or less. In some preferred embodiments, the thickness of the pressure-sensitive adhesive layer is approximately 300 μm or less, or may be 200 μm or less. In the case of a substrate-attached double-sided pressure-sensitive adhesive sheet in which pressure-sensitive adhesive layers are laminated on both sides of a fibrous substrate, a pressure-sensitive adhesive layer of the above thickness may be provided on each side of the substrate. The thickness of each adhesive layer may be the same or different.

[0101] <Adhesive sheet> The total thickness of the PSA sheet disclosed herein (including the thickness of the PSA layer and substrate, but excluding the thickness of the release liner) is not particularly limited, and is suitably approximately 1500 μm or less, and may be 1200 μm or less, or 1000 μm or less (e.g., less than 1000 μm). In some preferred embodiments, the total thickness of the PSA sheet is approximately 750 μm or less, 500 μm or less, 450 μm or less, 400 μm or less, or 350 μm or less, from the viewpoints of preventing blocking and saving resources. The total thickness of the PSA sheet is typically 30 μm or more, and may be 50 μm or more, or 70 μm or more. In some embodiments, the total thickness of the PSA sheet is preferably 80 μm or more, more preferably 120 μm or more, and may be 160 μm or more, 200 μm or more, 250 μm or more, or 300 μm or more, from the viewpoint of easily obtaining good adhesive properties, impact resistance, and ability to conform to steps or irregularities that may be present on the surface of the adherend, etc. The technology disclosed herein can be preferably implemented in a PSA sheet having a total thickness within the above range.

[0102] Although not particularly limited, the adhesive strength of the pressure-sensitive adhesive sheet disclosed herein, measured under conditions of 23°C, 50% RH, a pulling rate of 300 mm / min, and a peel angle of 180°, is preferably 10 N / 10 mm or more, more preferably 15 N / 10 mm or more, even more preferably 20 N / 10 mm or more, and particularly preferably 25 N / 10 mm or more, and may be greater than 25 N / 10 mm or even 27 N / 10 mm or more. The upper limit of the adhesive strength is not particularly limited, and may be, for example, about 50 N / 10 mm or less, or about 40 N / 10 mm or less. The adhesive strength is measured by pressing the adhesive surface of the pressure-sensitive adhesive sheet against the surface of a stainless steel plate (SUS304 plate) as an adherend by rolling a 2 kg roller back and forth once, leaving it for 30 minutes, and then measuring it in accordance with JIS Z 0237 under conditions of a pulling rate of 300 mm / min and a peel angle of 180°. More specifically, the adhesive strength is measured by the method described in the Examples below.

[0103] In some embodiments of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive sheet preferably has a holding power sufficient to prevent the measurement sample from falling off after one hour in a holding power test conducted under the following conditions: a load of 500 g, an adhesive area of ​​10 mm (width) × 20 mm (length), and at 70°C. Pressure-sensitive adhesive sheets having the above-described holding power characteristics have high cohesive strength and are therefore suitable for use as pressure-sensitive adhesive sheets with excellent adhesive reliability. In some preferred embodiments of the pressure-sensitive adhesive sheet, after the holding power test, the measurement sample preferably has a displacement distance of less than 3.0 mm from the initial application position, more preferably less than 2.0 mm, and even more preferably 1.8 mm or less (e.g., 1.5 mm or less). The holding power test is specifically conducted by the method described in the Examples below.

[0104] In some embodiments of the PSA sheet disclosed herein, in an anti-blocking test performed by the method described in the Examples below, the PSA sheet suitably has an adhesive overhang length (anti-blocking property) of 150 μm or less, preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 40 μm or less (e.g., 35 μm or less, 30 μm or less, 25 μm or less, or 20 μm or less). PSA sheets having a thickness of at least one of the above-mentioned lower limits (e.g., 40 μm or more, 80 μm or more, 120 μm or more) on one or both sides (e.g., both sides) of a fibrous substrate, and satisfying one of the above-mentioned PSA overhang lengths, are preferred. There is no particular lower limit on the overhang length, and from the viewpoint of anti-blocking, the shorter the better. In some embodiments, taking into consideration the balance with other properties (e.g., hot melt coatability), the overhang length may be, for example, 3 μm or more, 5 μm or more, 10 μm or more, 15 μm or more, or 20 μm or more.

[0105] <Application> The adhesive composition or adhesive sheet disclosed herein is useful for joining components in various office automation equipment (e.g., PCs), home appliances (e.g., rice cookers, refrigerators), automobiles, building materials (e.g., housing construction materials), etc. (e.g., for fixing various parts in such products).

[0106] The matters disclosed by this specification include the following: [1] A pressure-sensitive adhesive sheet comprising a fibrous base material and a pressure-sensitive adhesive layer laminated on the fibrous base material, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer comprises a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, a tackifying resin, and a plasticizer; The pressure-sensitive adhesive has a shear viscosity at 195°C of 1300 Pa·s or more and 3000 Pa·s or less, The above fibrous base material has a basis weight of 30 g / m 2 and a thickness of 60 μm or less, The pressure-sensitive adhesive sheet, wherein the amount of organic solvent remaining in the pressure-sensitive adhesive layer is less than 1000 ppm. [2] The PSA contains a tackifier resin (A1) having a softening point of 60°C or higher and lower than 120°C, The pressure-sensitive adhesive sheet according to [1] above, wherein the weight ratio of the content of the plasticizer to the content of the tackifier resin (A1) (plasticizer / A1) is greater than 0.060 and not greater than 0.200. [3] The pressure-sensitive adhesive contains a tackifier resin (A1) having a softening point of 60°C or higher and lower than 120°C, The pressure-sensitive adhesive sheet according to [1] or [2] above, wherein the total content of the tackifier resin (A1) and the plasticizer in the pressure-sensitive adhesive is 70 parts by weight or more and less than 100 parts by weight per 100 parts by weight of the block copolymer. [4] The PSA contains a tackifier resin (A1) having a softening point of 60°C or higher and lower than 120°C, and a tackifier resin (A3) having a softening point of 150°C or higher, The pressure-sensitive adhesive sheet according to any one of [1] to [3] above, wherein the weight ratio ((A1 + plasticizer) / A3) of the total content of the tackifier resin (A1) and the plasticizer to the content of the tackifier resin (A3) in the pressure-sensitive adhesive is 3.5 or more and 5.0 or less. [5] The block copolymer is a styrene-based block copolymer, The pressure-sensitive adhesive sheet according to any one of [1] to [4] above, wherein the styrene content of the styrene-based block copolymer is 10% by weight or more and 22% by weight or less. [6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein the content of the phenolic tackifier resin in the pressure-sensitive adhesive layer is less than 1 part by weight per 100 parts by weight of the block copolymer. [7] The pressure-sensitive adhesive sheet according to any one of [1] to [6] above, wherein the pressure-sensitive adhesive layer has a thickness of 40 μm or more and 200 μm or less. [8] The pressure-sensitive adhesive sheet according to any one of [1] to [7] above, which has an adhesive strength of 20 N / 10 mm or more when measured under conditions of a tensile speed of 300 mm / min and a peel angle of 180 degrees in an environment of 23°C and 50% RH. [9] 1 cm 2The adhesive sheet according to any one of [1] to [8] above, wherein the adhesive protrusion length measured under the condition of applying a load of 2 kg to the adhesive sheet at a corner at 40°C for 12 hours is 100 μm or less. [Example]

[0107] Several examples of the present invention will be described below, but it is not intended that the present invention be limited to those shown in these examples. In the following description, "parts" and "%" are by weight unless otherwise specified. Furthermore, the amount of each material used is based on the amount excluding the solvent unless otherwise specified.

[0108] Example 1 The mixture contained 100 parts of a styrene-isoprene block copolymer (manufactured by Zeon Corporation, product name "Quintac 3520," styrene content 15%, diblock ratio 78%), 20 parts of a rosin resin (manufactured by Arakawa Chemical Industries, product name "Pensel D160") as a tackifier resin, 8 parts of a styrene resin (manufactured by Kraton Corporation, product name "SA140"), and 72 parts of a terpene resin (manufactured by Yasuhara Chemical Co., Ltd., product name "YS Resin PX1150N") as a plasticizer, 8 parts of a paraffin oil (manufactured by Idemitsu Kosan Co., Ltd., product name "Diana Process Oil PW-90") as a plasticizer, and 3 parts of an antioxidant (manufactured by BASF, product name "IRGANOX CB612" (BASF, product name "IRGAFOS 168" and product name "IRGANOX CB612") as an antioxidant. The adhesive composition, which is a mixture of "Aggregate 100% Polyethylene Glycol" and "Aggregate 565" (a blend of "Aggregate 100% Polyethylene Glycol" and "Aggregate 565") at a ratio of 2:1, was heated and melted in a twin-screw extruder, and coated at a coating temperature of 195°C by a hot melt coating method on the release-treated surface of a 75 μm-thick PET film (release film) that had been release-treated with a silicone-based release agent to form an adhesive layer with a thickness of 150 μm. The adhesive layer was then coated on a fibrous substrate, Substrate A (basis weight 14 g / m2). 2The adhesive layer was laminated on the first surface of a 42 μm-thick pulp-based nonwoven fabric to form a first PSA layer. In the same manner, a second PSA layer was laminated on the second surface of the above substrate. In this manner, a PSA sheet according to this example (a substrate-attached double-sided PSA sheet having substrate A, a first PSA layer laminated on the first surface of substrate A, and a second PSA layer laminated on the second surface of substrate A) was obtained, with the surface (adhesive surface) of each PSA layer protected by the release film.

[0109] <Examples 2 and 3 and Comparative Example 1> Except for changing the adhesive composition as shown in Table 1, the same procedure as in Example 1 was carried out to prepare adhesive sheets (double-sided adhesive sheets with a substrate) according to each example.

[0110] <Comparative Example 2> The adhesive was prepared in the same manner as in Example 1, except that the adhesive composition was changed as shown in Table 1. An attempt was made to form an adhesive layer using the hot melt coating method in the same manner, but the adhesive had insufficient fluidity and could not be applied uniformly, so the production of the adhesive sheet was discontinued.

[0111] Example 4 and Comparative Example 3 As the fibrous base material, base material B (basis weight 35 g / m) shown in Table 2 was used instead of base material A. 2 , pulp-based nonwoven fabric with a thickness of 25 μm) or substrate C (basis weight 22.6 g / m 2 A PSA sheet (double-sided PSA sheet with a substrate) according to each example was produced in the same manner as in Example 1, except that a 76 μm thick pulp-based nonwoven fabric was used.

[0112] <Comparative Example 4> In the same manner as in Example 1, a release film that had been release-treated with a silicone-based release agent was attached to the surface of a 150 μm thick adhesive layer formed on the release film, thereby producing an adhesive sheet (substrate-less double-sided adhesive sheet) consisting of the 150 μm thick adhesive layer, which was used as the adhesive sheet for Comparative Example 4.

[0113] The materials used in the table are as follows: (styrene-based block copolymer) Quintac 3520: Zeon Corporation's product name: Quintac 3520 (styrene-isoprene block copolymer, styrene content 15%, diblock ratio 78%) (tackifying resin) D160: Arakawa Chemical Industries' product name "Pensel D160", a rosin-based resin with a softening point of 157°C T145: Yasuhara Chemical's product name "YS Polyster T145", a terpene phenol resin with a softening point of 145°C SA140: Kraton SA140, a styrene-based resin with a softening point of 137°C. PX1150N: Yasuhara Chemical's product name "YS Resin PX1150N", a terpene resin with a softening point of 115°C (plasticizer) "PW-90": Idemitsu Kosan's product name "Diana Process Oil PW-90", a paraffin-based oil

[0114] <Evaluation method> (shear viscosity) The measurement was performed using a Thermo Fisher Scientific rheometer viscometer (HAAKE RheoStress 6000) with a circular parallel plate (P / N: 222-1873) at a gap of 0.5 mm, a measurement temperature of 195°C, and a shear rate of 0.1 sec. -1 1 second from -1 From the viscosity when continuously changed from shear rate 0.1 sec -1 The viscosity was read at .

[0115] (holding force) The release film covering one adhesive surface of a pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) was peeled off and attached to a 25 μm thick PET film for backing. This backed pressure-sensitive adhesive sheet was cut to a size of 10 mm wide and 100 mm long to prepare a measurement sample. The release film covering the other adhesive surface of the measurement sample was peeled off, and the other adhesive surface was pressed against a stainless steel plate (SUS304 plate) as an adherend, with an adhesive area of ​​10 mm wide and 20 mm long, by rolling a 2 kg roller back and forth once. The measurement sample thus attached to the adherend was then draped in a 70°C environment and left for 30 minutes. After that, a 500 g load was applied to the free end of the measurement sample, and the sample was left in a 70°C environment with the load applied for 1 hour in accordance with JIS Z0237. The time [min] until the measurement sample peeled off from the adherend and fell was measured. If the sample had not fallen after 1 hour, the time [min] until the sample fell was recorded as ">60".

[0116] (repulsion resistance) A release film covering one adhesive surface of a double-sided pressure-sensitive adhesive sheet was peeled off, and an aluminum plate (0.5 mm thick, 20 mm wide, 180 mm long) was attached to the exposed adhesive surface with a hand roller. The pressure-sensitive adhesive sheet was then cut to the size of the aluminum plate to prepare a test specimen. After storing this test specimen in an environment of 23°C and 50% RH for one day, the release film covering the other adhesive surface was peeled off, and the specimen was pressure-bonded to a 2 mm thick polypropylene (PP) plate cut to a size of 30 mm x 200 mm and stored in the same environment for 24 hours. Next, as shown in Figure 2, the PP plate with the attached test specimen was curved into an arch shape with a chord length of 190 mm, with the test specimen facing outward, and placed in a jig with a U-shaped cross section. This was then stored in an atmosphere of 70°C for 72 hours, and the distance h [mm] by which the edge of the test specimen rose above the surface of the PP plate was measured (Figure 3), which was used as the repulsion resistance. 2 and 3, reference numerals 100, 200, 300, and 400 respectively indicate an adhesive sheet, an aluminum plate, a PP plate, and a jig.

[0117] (Coatability) When the adhesive composition of each example could be hot-melt coated as a continuous film under the conditions described in Example 1, it was evaluated as "Good" (good coatability), and when a continuous film could not be formed, it was evaluated as "Poor coatability."

[0118] (Adhesive strength) The release liner covering one adhesive surface of a pressure-sensitive adhesive sheet (double-sided pressure-sensitive adhesive sheet) was peeled off and attached to a 50 μm-thick PET film for backing. This backed pressure-sensitive adhesive sheet was cut to a size of 10 mm wide and 100 mm long to prepare a test piece. The other adhesive surface (surface to be measured) of the test piece was exposed in an environment of 23°C and 50% RH, and the exposed adhesive surface of the test piece was pressed against the surface of a stainless steel plate (SUS304 plate) using a 2 kg roller with one reciprocating motion. After leaving the test piece in the same environment for 30 minutes, the 180° peel adhesive strength [N / 10 mm] was measured using a tensile tester at a pulling rate of 300 mm / min in accordance with JIS Z 0237. The measurement was performed three times (i.e., N = 3), and the arithmetic average value was calculated. Note that a single-sided pressure-sensitive adhesive sheet does not require a PET film backing.

[0119] (Anti-blocking properties) A laminate having a PET film / adhesive layer (double-sided adhesive sheet) / PET film configuration was formed by peeling off the release liner covering one adhesive surface of a pressure-sensitive adhesive sheet (double-sided adhesive sheet) and applying a 50 μm-thick PET film. The release liner covering the other adhesive surface was then peeled off and a 50 μm-thick PET film was applied. This laminate was then cut into 10 mm squares to prepare test specimens. As shown schematically in FIG. 4 , the test specimen 4 was sandwiched between two 2 mm-thick polypropylene plates 42, 42, and a 2 kg load 46 was applied to the upper polypropylene plate 42. The specimen was then left in this condition for 12 hours at 40°C. After this time, the length of adhesive protruding from the PET film on each side of the test specimen was observed using a digital microscope at an appropriate magnification (50x in this experiment) to measure the average protrusion length. The arithmetic mean of the average protrusion lengths on the four sides was used as the evaluation result for the "anti-blocking properties" of the test specimen. The digital microscope observations were performed within approximately 60 minutes after the load was released and the test specimens were removed from between the two polypropylene plates under an environment of 23°C and 50% RH. The time from the release of the load to the observation was adjusted so that it was roughly constant for each test specimen.

[0120] The outline of each example and the evaluation results are shown in Tables 1 and 2. In the composition column of the table, "-" indicates that the material was not used.

[0121] [Table 1]

[0122] [Table 2]

[0123] As shown in Table 1, the PSA sheets of Examples 1 to 3, which were produced using a PSA with a shear viscosity in the range of 1300 to 3000 Pa·s and Substrate A, were superior in both holding power and repulsion resistance compared to the PSA sheet of Comparative Example 1, which used a PSA with too low a shear viscosity. Comparative Example 2, which had too high a shear viscosity, had poor hot melt coatability. Although not shown in the table, in measuring the holding power of the PSA sheets of Examples 1 to 3, the displacement distance (mm) from the initial application position of the measurement sample was measured after 1 hour; the results were 1.4 mm for Example 1, 1.7 mm for Example 2, and 1.5 mm for Example 3.

[0124] Also, as shown in Table 2, the basis weight is 30 g / m 2The pressure-sensitive adhesive sheets of Examples 1 and 4, which used fibrous substrates (substrates A and B) satisfying the above specifications and a thickness of 60 μm or less, exhibited good pressure-sensitive adhesive impregnation into the substrate and exhibited high adhesive strength. On the other hand, the pressure-sensitive adhesive sheet of Comparative Example 3, which used a fibrous substrate (substrate C) with a thickness of 76 μm, exhibited insufficient pressure-sensitive adhesive impregnation into the substrate, and peeling progressed in the form of the pressure-sensitive adhesive sheet tearing at the pressure-sensitive adhesive-free portions inside the substrate during pressure-sensitive adhesive strength measurements. As a result, a significantly lower pressure-sensitive adhesive strength than the pressure-sensitive adhesive's inherent potential was observed. The pressure-sensitive adhesive sheet of Comparative Example 4, which did not have a fibrous substrate (substrate-less pressure-sensitive adhesive sheet), exhibited poor blocking prevention. Furthermore, the pressure-sensitive adhesive overflowed longer in Comparative Example 3 than in Examples 1 and 4, demonstrating that good pressure-sensitive adhesive impregnation into the substrate is also effective in suppressing blocking.

[0125] Qualitative and quantitative analysis of residual solvents in the adhesives (layers) of Examples 1 to 4 and Comparative Examples 1 to 4 was performed using gas chromatography mass spectrometry (GC / MS) in accordance with JIS A 1901:2015, and it was confirmed that all were less than 1000 ppm (more specifically, 500 ppm or less). The remaining amounts of the 54 organic solvents evaluated were as shown in Table 3 (see https: / / www.mhlw.go.jp / new-info / kobetu / roudou / gyousei / anzen / dl / 120815-01.pdf). The specific measurement conditions for GC / MS were as follows:

[0126] [GC] 5cm sample 2 The sample was collected and sealed in a headspace vial. It was then heated at 80°C for 30 minutes in a headspace sampler (HSS), and 1 mL of the gas phase after heating was injected into a GC. (Device) HSS:Agilent Technologies, G1888 GC:Agilent Technologies, 6890N (Measurement conditions) 1.HSS conditions Heating temperature: 80℃ Heating time: 30min Sample loop temperature: 160℃ Transfer line temperature: 200℃ Pressurization time: 0.20 min Loop filling time: 0.20 min Loop equilibration time: 0.05 min Injection time: 0.50min 2.GC conditions Column: HP-1 (0.250 mmφ×30 m, df=1.0 μm) Column temperature: 40°C (3 min) → 10°C / min → 120°C → 20°C / min → 300°C (10 min) Column flow rate (He): 1 mL / min Column pressure: constant flow mode (81 kPa) Inlet temperature: 250℃ Injection volume: 1mL Injection method: Split (20:1) Detector: FID Detector temperature: 250℃

[0127] [GC / MS] Approximately 150 mg of sample was weighed into a 20 mL vial, sealed, and heated in a headspace sampler. 1 mL of the evolved gas was then measured by GC / MS. (Device) HSS: Shimadzu HS-20 GC / MS: Shimadzu GCMS-QP2020 (HSS) Heating conditions: 200℃ x 30 minutes, 150℃ x 10 minutes (standard product) Sample line: 210℃ Transfer line: 220℃ (GC) Column: HP-5MS UI, 30m x 0.25mm id x 0.25μm film thickness Column temperature: 40°C (3 min) → +20°C / min → 300°C (Hold) Split Mode Split (20:1) Column pressure: 49.5 kPa (constant linear velocity mode) Carrier gas: He (1.0 mL / min) Inlet temperature: 250℃ Detector: MS (MS) Ionization method EI Electron energy: 70 eV EM voltage: 1.36V Source temperature: 230℃ Interface temperature: 300℃ Mass range (m / z): 10~800

[0128] [Table 3]

[0129] Although specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples exemplified above. [Explanation of symbols]

[0130] 1 adhesive sheet 11 adhesive layer, first adhesive layer 12 Second adhesive layer 15 Base material 21 Release liner

Claims

1. A pressure-sensitive adhesive sheet comprising a fibrous base material and a pressure-sensitive adhesive layer laminated on the fibrous base material, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer comprises a block copolymer of a monovinyl-substituted aromatic compound and a conjugated diene compound, a tackifying resin, and a plasticizer; the pressure-sensitive adhesive has a shear viscosity at 195°C of 1300 Pa s or more and 3000 Pa s or less; The fibrous base material has a basis weight of 30 g / m ２ and a thickness of 60 μm or less, A pressure-sensitive adhesive sheet, wherein the amount of organic solvent remaining in the pressure-sensitive adhesive layer is less than 1000 ppm.

2. the PSA contains a tackifier resin (A1) having a softening point of 60°C or higher and lower than 120°C, The pressure-sensitive adhesive sheet according to claim 1, wherein the weight ratio of the content of said plasticizer to the content of said tackifier resin (A1) (plasticizer / A1) is greater than 0.060 and not greater than 0.

200.

3. the PSA contains a tackifier resin (A1) having a softening point of 60°C or higher and lower than 120°C, 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the total content of the tackifier resin (A1) and the plasticizer in the pressure-sensitive adhesive is 70 parts by weight or more and less than 100 parts by weight per 100 parts by weight of the block copolymer.

4. The PSA comprises a tackifier resin (A1) having a softening point of 60°C or higher and lower than 120°C, and a tackifier resin (A3) having a softening point of 150°C or higher, 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the weight ratio ((A1 + plasticizer) / A3) of the total content of the tackifier resin (A1) and the plasticizer to the content of the tackifier resin (A3) in the pressure-sensitive adhesive is 3.5 or more and 5.0 or less.

5. the block copolymer is a styrene-based block copolymer, The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the styrene content of the styrene-based block copolymer is 10% by weight or more and 22% by weight or less.

6. The pressure-sensitive adhesive sheet according to claim 1 , wherein the content of the phenolic tackifier resin in the pressure-sensitive adhesive layer is less than 1 part by weight based on 100 parts by weight of the block copolymer.

7. The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a thickness of 40 μm or more and 200 μm or less.

8. The adhesive strength measured under the conditions of a pulling speed of 300 mm / min and a peel angle of 180 degrees in an environment of 23°C and 50% RH is 20 N / 10 mm or more, and 1 cm ２ 3. The pressure-sensitive adhesive sheet according to claim 1, wherein the length of pressure-sensitive adhesive protrusion measured under conditions of applying a load of 2 kg to the corner of the pressure-sensitive adhesive sheet at 40°C for 12 hours is 100 μm or less.

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