Laser processing adhesive sheet

Abstract

To provide an adhesive sheet that is applied to processing by a laser beam, which has improved high speed peel strength and low speed peel strength.SOLUTION: An adhesive sheet for laser processing has a resin film as a base material, and an adhesive layer provided on a first surface of the base material, wherein the adhesive layer contains a base polymer containing a natural rubber, a tackifier A having a Hansen solubility parameter distance between the natural rubber and the tackifier A of 1.5 or less, a tackifier B having a Hansen solubility parameter distance between the natural rubber and the tackifier B of 2.5 or more and 5.0 or less, and an isocyanate-based crosslinking agent. The content of the tackifier A is 40 pts.wt. or more and less than 100 pts.wt. with respect to 100 pts.wt. of the base polymer, and the content of the tackifier B is 5 pts.wt. or more and less than 35 pts.wt. with respect to 100 pts.wt. of the base polymer. The gel fraction of the adhesive layer is 15% or more and less than 60%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive sheet for laser processing. [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 a variety of fields for purposes such as joining, fixing, surface protection, masking, and marking, typically in the form of an adhesive sheet having an adhesive layer on a substrate. For example, Patent Documents 1 and 2 are technical documents relating to adhesive films that can be used for surface protection during laser processing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2018-526480 [Patent Document 2] Japanese Patent Application Publication No. 2020-6379 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, there has been growing interest in processing techniques using laser light. Laser processing techniques are widely used for cutting, drilling, and the like of various materials. Typical examples of lasers used in such processing include carbon dioxide lasers with a dominant wavelength of approximately 9.3 μm to 10.6 μm and short-wavelength lasers with a dominant wavelength of approximately 0.9 μm to 1.1 μm. One example of laser processing is a mode in which an adhesive sheet as an auxiliary material is attached to an adherend (a workpiece, hereinafter also referred to as "work"), and laser light is irradiated onto the workpiece to perform laser processing on the adhesive sheet and the workpiece together. It is preferable that the adhesive sheet that can be used in this mode has high-speed peel strength suitable for suppressing lifting and peeling due to the assist gas supplied during laser processing.

[0005] In particular, by using a short-wavelength laser beam with a dominant wavelength of approximately 0.9 μm to 1.1 μm, the energy required for processing can be efficiently applied to the workpiece. This can be advantageous from the viewpoint of speeding up processing and fine processing. On the other hand, in processing using a short-wavelength laser, the assist gas pressure tends to be high in order to speed up processing. For this reason, it is particularly desirable that a pressure-sensitive adhesive sheet intended for use in processing using a short-wavelength laser has a certain level of high-speed peel strength in order to prevent the occurrence of an event in which such high-pressure assist gas gets between the sheet and the workpiece and causes the sheet to lift off the workpiece.

[0006] Furthermore, after cutting or other processing is performed with a laser beam, the workpiece may then be subjected to post-processing such as bending or drilling. In this case, the adhesive sheet attached as an auxiliary material for laser processing continues to be used in the post-processing while remaining attached to the workpiece even after the laser processing. In this case, if the peel strength (especially the low-speed peel strength) of the adhesive sheet is too low, there is a concern that the adhesive sheet will not be able to withstand the bending, pulling, etc., that occurs during the post-processing, and peeling may occur. For this reason, it is desirable for the adhesive sheet used in laser processing to have a low-speed peel strength of at least a certain level in order to prevent peeling during the post-processing.

[0007] Incidentally, objects with polished surfaces (e.g., polished metal plates) are sometimes used as workpieces for laser processing, and in such cases, adhesive sheets for laser processing are sometimes attached to the polished surface of the workpiece. However, residues (hereinafter also referred to as "polishing residues") from the abrasives, cleaning agents, etc. used in polishing often remain on the polished surface without being thoroughly wiped off, and the adhesion of such residues can reduce the peel strength of the adhesive sheet to the workpiece. Even if the workpiece has a surface with such polishing residues attached, it is desirable for the adhesive sheet used in laser processing to have both excellent high-speed peel strength and excellent low-speed peel strength from the viewpoints of laser processability and suppression of peeling in subsequent processes.

[0008] In view of the above circumstances, an object of the present invention is to provide an adhesive sheet that is applicable to processing with laser light and that has both excellent high-speed peel strength and excellent low-speed peel strength. [Means for solving the problem]

[0009] This specification provides a pressure-sensitive adhesive sheet for laser processing, comprising a resin film as a substrate and a pressure-sensitive adhesive layer provided on a first surface of the substrate. The pressure-sensitive adhesive layer comprises a base polymer containing natural rubber, a tackifier, and an isocyanate-based crosslinking agent. The tackifier comprises at least tackifier A and tackifier B. Tackifier A has a Hansen solubility parameter distance Ra (NR-A) with natural rubber of 1.5 or less. Tackifier B has a Hansen solubility parameter distance Ra (NR-B) with natural rubber of 2.5 or more and 5.0 or less. The content of tackifier A is 40 parts by weight or more but less than 100 parts by weight per 100 parts by weight of the base polymer. The content of tackifier B is 5 parts by weight or more but less than 35 parts by weight per 100 parts by weight of the base polymer. The gel fraction of the pressure-sensitive adhesive layer is 15% or more but less than 60%.

[0010] The adhesive sheet thus constructed tends to have excellent high-speed peel strength, even when used on a workpiece having polishing residue attached thereto, which tends to reduce peel strength, so that it can maintain a favorable state of being attached to the adherend without floating or peeling due to impacts such as assist gas pressure during laser processing.Furthermore, the adhesive sheet thus constructed tends to have excellent low-speed peel strength, even when used on a workpiece having polishing residue attached thereto, which tends to reduce peel strength, so that it can suppress peeling of the adhesive sheet in the post-laser processing step, and can also suppress the generation of adhesive residue when peeled.

[0011] In some preferred embodiments of the PSA sheet, the difference between the Hansen solubility parameter distance Ra(NR-A) between the tackifier A and the natural rubber and the Hansen solubility parameter distance Ra(NR-B) between the tackifier B and the natural rubber is 1.8 or more. PSA sheets having such a configuration tend to have both excellent high-speed peel strength and excellent low-speed peel strength, even when used on workpieces having polishing residues or the like attached, which tend to reduce peel strength.

[0012] In some preferred embodiments, the tackifier A includes at least one selected from aliphatic petroleum resins. PSA sheets using such tackifier A can be suitably used in applications requiring high high-speed peel strength.

[0013] In some preferred embodiments, the tackifier B comprises at least one resin selected from the group consisting of a rosin resin, a rosin derivative resin, and a terpene resin. A PSA sheet using such a tackifier B is suitable for use in attaching to a workpiece having polishing residue or the like attached thereto, which tends to reduce peel strength.

[0014] In some embodiments, the substrate is a polyolefin resin film or a polyester resin film. A pressure-sensitive adhesive sheet having such a substrate is preferred because, when cut with a laser beam, it is easy to control the cutting width and form a cut edge surface with good shape accuracy.

[0015] The pressure-sensitive adhesive sheet disclosed herein can contain a laser beam absorbent as needed. By containing a laser beam absorbent in the pressure-sensitive adhesive sheet, the laser beam absorption rate can be increased, and the laser processability of the adherend to which the pressure-sensitive adhesive sheet is attached can be improved. From the viewpoint of easily achieving both good laser beam absorbency and desired adhesive properties, it is preferable that the laser beam absorbent be contained in at least the substrate.

[0016] In some embodiments, the laser beam absorbent may preferably be at least one selected from the group consisting of carbon black, titanium oxide, titanium black, iron-based oxides, and manganese-based oxides. From the viewpoint of stable availability of materials, preferred laser beam absorbents include carbon black and iron-based oxides.

[0017] In one preferred embodiment, the pressure-sensitive adhesive sheet disclosed herein is used by cutting with a short-wavelength laser beam (hereinafter also referred to as "specific laser beam") having a dominant wavelength in the range of 900 nm to 1100 nm. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view schematically illustrating a pressure-sensitive adhesive sheet according to an embodiment. [Figure 2] 1 is a cross-sectional view schematically illustrating a roll body around which a pressure-sensitive adhesive sheet according to one embodiment is wound. [Figure 3] FIG. 10 is a cross-sectional view schematically showing a pressure-sensitive adhesive sheet according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Preferred embodiments of the present invention are 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 for 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. Furthermore, in the following drawings, components and parts that perform the same function may be denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the embodiments shown in the drawings are schematic to clearly explain the present invention and do not necessarily accurately represent the size or scale of the pressure-sensitive adhesive sheet of the present invention that is actually provided as a product.

[0020] The concept of adhesive sheet as used herein may include those referred to as adhesive tape, adhesive label, adhesive film, etc. The adhesive layer is typically formed continuously, but is not limited to such a form, and may be an adhesive layer formed in a regular or random pattern such as a dotted or striped pattern. The adhesive sheet disclosed herein may be in the form of a roll or a sheet. Alternatively, it may be cut, punched, or otherwise processed into an appropriate shape depending on the application or mode of use.

[0021] As described above, the term "adhesive" in this specification refers to a material that exhibits a soft solid (viscoelastic) state in a temperature range around room temperature and has the property of easily adhering to an adherend by pressure. The adhesive referred to here is generally a material having a complex tensile modulus E as defined in "CA Dahlquist, "Adhesion: Fundamental and Practice", McLaren & Sons, (1966) p. 143". * (1Hz)<10 7 dyne / cm 2 The material may be a material having the properties satisfying the above (typically, a material having the above properties at 25°C).

[0022] <Adhesive sheet composition> The pressure-sensitive adhesive sheet disclosed herein has a pressure-sensitive adhesive layer on one surface (first surface) of a resin film as a substrate. The configuration of a pressure-sensitive adhesive sheet according to one embodiment is shown schematically in FIG. 1. This pressure-sensitive adhesive sheet 1 comprises a resin film 10 as a substrate and a pressure-sensitive adhesive layer 20 provided on one surface (first surface) 10A of the resin film 10, and is used by attaching the pressure-sensitive adhesive layer 20 to an adherend. In a preferred embodiment, the other surface (back surface, second surface) 10B of the resin film 10 has a releasable surface (release surface). Prior to use (i.e., prior to attachment to an adherend), the pressure-sensitive adhesive sheet 1 may be in the form of a roll 50, as shown in FIG. 2, wound around a core 52 such that the surface (adhesive surface) 20A of the pressure-sensitive adhesive layer 20 abuts against the back surface 10B of the resin film 10, thereby protecting the surface 20A. Alternatively, the pressure-sensitive adhesive sheet 1 may be in the form of a roll without a core 52, i.e., a so-called coreless roll in which the pressure-sensitive adhesive sheet 1 is wound alone. Alternatively, the pressure-sensitive adhesive sheet 1 before use may be in the form of a roll, or may be in a laminated form in which sheet-like (discrete) pressure-sensitive adhesive sheets are laminated by abutting the pressure-sensitive adhesive layer surface of one pressure-sensitive adhesive sheet against the back surface of another pressure-sensitive adhesive sheet, thereby protecting the adhesive surface 20A. Alternatively, the surface 20A of the pressure-sensitive adhesive sheet 1 before use may be protected by a release liner, rather than by the back surface of the substrate constituting the pressure-sensitive adhesive sheet.

[0023] In a preferred aspect of the pressure-sensitive adhesive sheet 1 of this embodiment, the resin film 10 includes a backing layer 11 constituting the other surface (second surface) 10B of the resin film 10, and a support layer 12 disposed on the inner side of the backing layer 11 (the side on which the pressure-sensitive adhesive layer 20 is provided), as shown in FIG. 3 . In a preferred aspect, the backing layer 11 is formed from a resin composition containing a release agent, such that the surface of the backing layer 11 (which also serves as the second surface 10B of the resin film 10) serves as a release surface. The support layer 12 may be a layer made of a resin composition that does not contain a release agent, or may be a layer made of a resin composition that contains a release agent. In an aspect in which one surface 10A of the resin film 10 is formed from the support layer 12, as in the example shown in FIG. 3 , from the viewpoint of the anchoring ability of the pressure-sensitive adhesive layer 20 to the resin film 10, it is preferable that the support layer 12 be a layer made of a resin composition that does not contain a release agent. In the adhesive sheet 2 shown in FIG. 3, the resin film 10 has a two-layer structure consisting of the back layer 11 and the support layer 12, but the structure of the resin film 10 is not limited to a two-layer structure.

[0024] <Adhesive layer> The PSA layer in the technology disclosed herein comprises a base polymer containing natural rubber, at least two tackifiers that differ in their compatibility with natural rubber, and a crosslinking agent (e.g., an isocyanate-based crosslinking agent). PSA layers composed of PSAs containing natural rubber tend to exhibit excellent high-speed peel strength. Furthermore, the use of natural rubber in combination with a tackifier that exhibits specific compatibility with natural rubber tends to favorably improve the adhesiveness of the PSA layer.

[0025] The PSA layer in the technology disclosed herein is not particularly limited as long as it contains natural rubber, a tackifier that exhibits a specific compatibility with natural rubber, and a crosslinking agent (e.g., an isocyanate-based crosslinking agent). For example, it may be composed of a known rubber-based PSA, acrylic-based PSA, polyester-based PSA, polyurethane-based PSA, silicone-based PSA, etc. From the viewpoint of adhesive performance, rubber-based PSAs are preferably used. Here, a rubber-based PSA refers to a PSA in which the main component of the polymer component contained in the PSA (typically, a component contained in an amount exceeding 50% by weight) is a rubber-based polymer. The same applies to acrylic-based PSA, polyester-based PSA, polyurethane-based PSA, silicone-based PSA, etc. The pressure-sensitive adhesive layer may have a single-layer structure or a laminate structure having two or more layers with the same or different compositions. From the viewpoint of improving the uniformity of the pressure-sensitive adhesive layer and exhibiting stable adhesiveness, a pressure-sensitive adhesive layer with a single-layer structure is preferred.

[0026] As the adhesive constituting the adhesive layer of the adhesive sheet disclosed herein, a rubber-based adhesive is particularly preferably used from the viewpoint of exhibiting better high-speed peel strength. Examples of the rubber-based adhesive include natural rubber-based adhesives and synthetic rubber-based adhesives.

[0027] The concept of the natural rubber-based PSA includes those in which the base polymer is natural rubber and those in which the base polymer is modified natural rubber. The natural rubber is not particularly limited, and examples thereof include standard Malaysian rubber (SMR), standard Vietnamese rubber (SVR), ribbed smoked sheet (RSS), pale crepe, etc. The modified natural rubber is preferably one in which 50% by weight or more (e.g., 60% by weight or more) of the structural moiety is derived from natural rubber. Specific examples of the modified natural rubber include, but are not limited to, acrylic-modified natural rubber. The "base polymer" of a PSA refers to the main rubbery polymer component contained in the PSA. The rubbery polymer is a polymer that exhibits rubber elasticity in a temperature range around room temperature. In this specification, the term "main component" refers to a component that accounts for more than 50% by weight, unless otherwise specified.

[0028] Specific examples of rubber-based polymers that serve as the base polymer of the synthetic rubber-based adhesive include polybutadiene, polyisoprene, butyl rubber, polyisobutylene, styrene-butadiene rubber (SBR), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), and the like.

[0029] In a preferred embodiment, the base polymer of the rubber-based pressure-sensitive adhesive layer is natural rubber. For example, natural rubber having a Mooney viscosity of approximately 10 to 60 under measurement conditions of MS(1+4)100°C (using an L-type rotor, preheating for 1 minute, viscosity measurement time for 4 minutes, test temperature 100°C) is preferred. Pressure-sensitive adhesive sheets having a natural rubber-based pressure-sensitive adhesive layer tend to exhibit a more rapid increase in adhesion to an adherend than pressure-sensitive adhesive sheets having a synthetic rubber-based pressure-sensitive adhesive layer. This can effectively prevent lifting or peeling of the pressure-sensitive adhesive sheet due to assist gas pressure, even if the time between attaching the pressure-sensitive adhesive sheet to the workpiece (adherend) and subjecting the workpiece to laser processing is shortened.

[0030] The rubber-based pressure-sensitive adhesive layer in the technology disclosed herein may have a composition in which a base polymer is blended with another polymer (hereinafter also referred to as a secondary polymer). Such secondary polymers may be, for example, acrylic polymers, polyester polymers, polyurethane polymers, silicone polymers, etc., which can serve as base polymers for acrylic pressure-sensitive adhesives, polyester pressure-sensitive adhesives, polyurethane pressure-sensitive adhesives, silicone pressure-sensitive adhesives, etc. Alternatively, the secondary polymers may be any of the rubber-based polymers described above other than the base polymers. Such secondary polymers may be used alone or in combination of two or more types.

[0031] Such a secondary polymer is used in an amount of 100 parts by weight or less (when two or more secondary polymers are used, this refers to the total amount) per 100 parts by weight of the base polymer. Typically, the amount of secondary polymer used per 100 parts by weight of the base polymer is suitably 70 parts by weight or less, and preferably 50 parts by weight or less. The rubber-based PSA layer may be substantially free of secondary polymers (i.e., substantially 100% by weight of the polymer components is the base polymer). Alternatively, the rubber-based PSA layer may be substantially free of polymer components other than rubber-based polymers (for example, a rubber-based PSA layer substantially free of polymer components other than natural rubber and modified natural rubber).

[0032] The pressure-sensitive adhesive sheet disclosed herein may have an acrylic pressure-sensitive adhesive layer composed of an acrylic pressure-sensitive adhesive. Examples of preferred acrylic pressure-sensitive adhesives include those in which the base polymer (the main component of the polymer) is an acrylic polymer having a monomer composition in which an alkyl (meth)acrylate such as butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate is the main component, and a modifying monomer copolymerizable with the alkyl (meth)acrylate is added as needed. Examples of the modifying monomer include hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate; carboxyl group-containing monomers such as (meth)acrylic acid; styrene-based monomers such as styrene; and vinyl esters such as vinyl acetate. Such acrylic pressure-sensitive adhesives can be obtained by conventional polymerization methods such as solution polymerization, emulsion polymerization, and ultraviolet (UV) polymerization.

[0033] The adhesive layer (e.g., a rubber-based adhesive layer) may contain a laser beam absorbent as needed. That is, the adhesive layer may be a laser beam absorbing layer. In an adhesive layer consisting of multiple layers, the laser beam absorbent may be contained in at least one of the layers. As the laser beam absorbent to be contained in the adhesive layer, one or more types may be appropriately selected from the laser beam absorbents exemplified above. The content of the laser beam absorbent in the adhesive layer is usually 5 wt % or less of the adhesive layer, and from the viewpoint of adhesive performance, 3 wt % or less is preferable, and it may be 1 wt % or less. The technology disclosed herein may also be preferably implemented in an embodiment in which the adhesive layer does not substantially contain a laser beam absorbent.

[0034] <Tackifier> The pressure-sensitive adhesive layer disclosed herein contains a tackifier. The tackifier may be selected from various known tackifier resins, such as rosin-based resins, rosin derivative resins, petroleum resins (C5-based, C9-based, etc.), terpene-based resins, ketone-based resins, and xylene-based resins. Examples of the rosin-based resins include gum rosin, wood rosin, and tall oil rosin, as well as stabilized rosin, polymerized rosin, and modified rosin. Examples of the rosin derivative resins include esters of the rosin-based resins, phenol-modified resins, and esters thereof. Examples of the petroleum resins include aliphatic petroleum resins, aromatic petroleum resins, copolymerized petroleum resins, alicyclic petroleum resins, and hydrogenated versions of these. Examples of the terpene-based resins include α-pinene resins, β-pinene resins, aromatic-modified terpene resins, and terpene-phenol resins. Examples of the ketone-based resins include ketone-based resins obtained by condensation of ketones with formaldehyde. Among these, preferred tackifiers include rosin resins, rosin derivative resins, aliphatic (C5) petroleum resins, and terpene resins. These tackifier resins can be suitably used in certain embodiments, such as a rubber-based pressure-sensitive adhesive layer.

[0035] The Hansen solubility parameter (HSP) is widely known as an index of the solubility of a substance. The Hansen solubility parameter (HSP) is a three-dimensional representation of the Hildebrand solubility parameter δ, which is divided into three components: the dispersion term δd, the polar term δp, and the hydrogen bonding term δh. δ2 = δd 2 +δp 2 +δh 2 The dispersion term δd indicates the effect of dispersion force, the polar term δp indicates the effect of dipole-dipole force, and the hydrogen bond term δh indicates the effect of hydrogen bond force. The HSP distance Ra between two substances is calculated as Ra = {4 × Δδd 2 +Δδp 2 +Δδh 2} 1 / 2 The Hansen solubility parameters are expressed as follows: the smaller the Ra, the higher the compatibility, and the larger the Ra, the lower the compatibility. Details of the Hansen solubility parameters are described in Charles M. Hansen, Hansen Solubility Parameters: A Users Handbook (CRC Press, 2007), and for substances for which literature values ​​are unknown, they can be calculated using known computer software such as Hansen Solubility Parameters in Practice (HSPiP).

[0036] The PSA layer disclosed herein contains, as a tackifier, a tackifier A that has relatively high compatibility with natural rubber. Specifically, the HSP distance between tackifier A and natural rubber (hereinafter also referred to as "Ra(NR-A)") is 1.5 or less. Such tackifiers A tend to have high compatibility with natural rubber, and by using them in combination with natural rubber, the PSA layer tends to maintain high uniformity and improve adhesion properties (e.g., low-speed peel strength) even when a relatively large amount of tackifier is contained.

[0037] From the viewpoint of improving low-speed peel strength, Ra(NR-A), which is the HSP distance between tackifier A and natural rubber, is more preferably 1.2 or less (e.g., 1.0 or less), even more preferably 0.9 or less, and may be 0.88 or less, 0.87 or less, 0.86 or less, or 0.85 or less. The lower limit of Ra(NR-A) is not particularly limited, but from the viewpoint of adhesive properties, it is usually appropriate that it is 0.3 or more, preferably 0.5 or more, more preferably 0.6 or more, even more preferably 0.7 or more, and may be 0.75 or more, or 0.8 or more.

[0038] In addition, when the adhesive layer disclosed herein contains two or more types of tackifier A, the HSP distance between tackifier A and natural rubber, Ra(NR-A), is the weighted average of the HSP distances between each tackifier A and natural rubber, calculated by the weight-based content of each tackifier A.

[0039] An example of a tackifier that can be suitably used as tackifier A is a C5 petroleum resin. Examples of the C5 petroleum resin include aliphatic petroleum resins, alicyclic petroleum resins, and hydrogenated versions of these. As tackifier A, one of these can be used alone or two or more can be used in combination.

[0040] The amount of tackifier A used (when two or more types of tackifiers A are used, the total amount) is typically approximately 20 to 170 parts by weight (preferably approximately 30 to 150 parts by weight) per 100 parts by weight of base polymer. From the viewpoint of improving high-speed peel strength, in some embodiments, the amount of tackifier A used may be, for example, 35 parts by weight or more, 40 parts by weight or more, or even 45 parts by weight or more per 100 parts by weight of base polymer. Furthermore, from the viewpoint of avoiding adhesive residue due to reduced cohesive strength, in some embodiments, the amount of tackifier A used per 100 parts by weight of base polymer may be, for example, 120 parts by weight or less, or even less than 100 parts by weight. In some embodiments, the amount of tackifier A used per 100 parts by weight of base polymer may be, for example, 95 parts by weight or less, 80 parts by weight or less, 70 parts by weight or less, 60 parts by weight or less, or 55 parts by weight or less. Reducing the amount of tackifier A used can be advantageous, for example, from the standpoint of reducing the workload when peeling the PSA sheet from the adherend and preventing the PSA sheet from tearing.

[0041] The PSA layer disclosed herein further contains, as a tackifier, a tackifier B that has relatively low compatibility with natural rubber. Specifically, the HSP distance between tackifier B and natural rubber (hereinafter also referred to as "Ra(NR-B)") is 2.5 or greater. Such tackifier B tends to have high affinity for residues (polishing residues) of abrasives, detergents, etc., which can be a factor in reducing peel strength. Therefore, a PSA layer containing tackifier B tends to improve both low-speed peel strength and high-speed peel strength, even for workpieces with polishing residues attached to their surfaces. From the viewpoint of maintaining the uniformity of the PSA layer, it is preferable that Ra(NR-B), the HSP distance between tackifier B and natural rubber, is not too large. From this viewpoint, Ra(NR-B) is preferably 5.0 or less. For example, when Ra(NR-B) is 2.5 or more and 5.0 or less, the adhesive has a sufficiently high affinity for both natural rubber and polishing residues, and therefore when used together with natural rubber, the adhesive tends to improve the peel strength (low-speed peel strength and high-speed peel strength) even for workpieces that have polishing residues present.

[0042] From the viewpoint of improving affinity with residues present on the surface of the object to be processed, Ra(NR-B), which is the HSP distance between tackifier B and natural rubber, is more preferably 2.6 or more (e.g., 2.65 or more), even more preferably 2.7 or more, and particularly preferably 2.8 or more (e.g., 2.85 or more). From the viewpoint of uniformity of the pressure-sensitive adhesive layer, Ra(NR-B) is more preferably 4.5 or less, even more preferably 4.0 or less, and particularly preferably 3.0 or less (e.g., 2.9 or less).

[0043] In addition, when the adhesive layer disclosed herein contains two or more types of tackifier B, the HSP distance between tackifier B and natural rubber, Ra(NR-B), is the weighted average of the HSP distances between each tackifier B and natural rubber, calculated by the weight-based content of each tackifier B.

[0044] Examples of tackifiers that can be suitably used as tackifier B include rosin-based resins, rosin derivative resins, C9 petroleum resins, terpene-based resins, ketone-based resins, and xylene-based resins. Examples of the rosin-based resins include rosins such as gum rosin, wood rosin, and tall oil rosin, as well as stabilized rosin, polymerized rosin, and modified rosin. Examples of the rosin derivative resins include esters of the rosin-based resins, phenol-modified resins, and esterified products thereof. Examples of the C9 petroleum resins include aromatic petroleum resins, copolymerized petroleum resins, and hydrogenated versions of these. Examples of the terpene-based resins include α-pinene resins, β-pinene resins, aromatic-modified terpene resins, and terpene phenol-based resins. Examples of the ketone-based resins include ketone-based resins obtained by condensation of ketones with formaldehyde. Examples of the xylene-based resin include xylene resins formed by crosslinking m-xylene with methylene bonds or ether bonds, and resins obtained by modifying these with phenols or polyhydric alcohols. Among these, rosin-based resins, rosin derivative resins, terpene-based resins, and xylene-based resins are preferred, with rosin-based resins, rosin derivative resins, and terpene-based resins being particularly preferred. As the tackifier B, one of these resins can be used alone, or two or more can be used in combination.

[0045] The amount of tackifier B used (when two or more types of tackifiers B are used, the total amount) is typically approximately 0.5 to 75 parts by weight (preferably approximately 1 to 60 parts by weight) per 100 parts by weight of base polymer. From the viewpoint of improving low-speed peel strength, in some embodiments, the amount of tackifier B used may be, for example, 3 parts by weight or more, 5 parts by weight or more, or 7 parts by weight or more per 100 parts by weight of base polymer. Furthermore, from the viewpoint of avoiding adhesive residue due to reduced cohesive strength, in some embodiments, the amount of tackifier B used per 100 parts by weight of base polymer may be, for example, 50 parts by weight or less, 40 parts by weight or less, or less than 35 parts by weight. In some embodiments, the amount of tackifier B used per 100 parts by weight of base polymer may be, for example, 32 parts by weight or less, 30 parts by weight or less, 25 parts by weight or less, 20 parts by weight or less, or 15 parts by weight or less. Reducing the amount of tackifier B used can be advantageous, for example, from the standpoint of reducing the workload when peeling the PSA sheet from the adherend and preventing the PSA sheet from tearing.

[0046] The relationship between Ra(NR-A) and Ra(NR-B) is not particularly limited. From the viewpoint of imparting affinity to both natural rubber and polishing residue, it is effective to use a combination of two or more tackifiers that differ in compatibility with natural rubber. From this viewpoint, it is preferable to use a combination of tackifier A and tackifier B, where the difference between Ra(NR-A) and Ra(NR-B) is 1.2 or more. The difference between Ra(NR-A) and Ra(NR-B) is more preferably 1.5 or more, even more preferably 1.8 or more, and particularly preferably 2.0 or more. Furthermore, from the viewpoint of improving compatibility in the pressure-sensitive adhesive layer and improving adhesive properties, the difference between Ra(NR-A) and Ra(NR-B) is preferably 4.5 or less, more preferably 3.5 or less (for example, 3.0 or less), even more preferably 2.5 or less, and may be 2.3 or less.

[0047] The PSA layer disclosed herein may further contain a tackifier other than tackifier A and tackifier B, provided that the effects of the present invention are not significantly impaired. Examples of such other tackifiers include those having an HSP distance from natural rubber of more than 1.5 and less than 2.5, or more than 5.0. From the perspective of maintaining the uniformity of the PSA layer, it is preferable to select as the other tackifier a tackifier having an HSP distance from natural rubber of more than 1.5 and less than 2.5.

[0048] The amount of the other tackifier used is not particularly limited. The amount of the other tackifier used is usually 20 parts by weight or less per 100 parts by weight of the base polymer, and may be 10 parts by weight or less, 5 parts by weight or less, 3 parts by weight or less, or 1 part by weight or less. From the viewpoint of simplifying the composition, in a preferred embodiment, the PSA layer disclosed herein does not contain any other tackifiers other than tackifier A and tackifier B.

[0049] The total amount of tackifier used is typically approximately 20 to 200 parts by weight (preferably approximately 30 to 100 parts by weight) per 100 parts by weight of base polymer. From the viewpoint of improving high-speed peel strength, in some embodiments, the amount of tackifier used may be, for example, 30 parts by weight or more, 40 parts by weight or more, or 45 parts by weight or more per 100 parts by weight of base polymer. Furthermore, from the viewpoint of avoiding adhesive residue due to reduced cohesive strength, in some embodiments, the amount of tackifier used per 100 parts by weight of base polymer may be, for example, 85 parts by weight or less, or 75 parts by weight or less. In some embodiments, the amount of tackifier used per 100 parts by weight of base polymer may be, for example, less than 70 parts by weight, 65 parts by weight or less, 55 parts by weight or less, or 50 parts by weight or less. Reducing the amount of tackifier used can be advantageous, for example, from the viewpoint of reducing the workload when peeling the PSA sheet from the adherend and preventing the PSA sheet from tearing.

[0050] The pressure-sensitive adhesive layer disclosed herein contains a crosslinking agent. The use of a crosslinking agent can impart appropriate cohesive strength to the pressure-sensitive adhesive layer. A pressure-sensitive adhesive layer containing a crosslinking agent can be obtained, for example, by forming a pressure-sensitive adhesive layer using a pressure-sensitive adhesive composition containing the crosslinking agent. The crosslinking agent can be contained in the pressure-sensitive adhesive layer in a form after crosslinking reaction, a form before crosslinking reaction, a partially crosslinked form, an intermediate or composite form thereof, or the like. The crosslinking agent is typically contained in the pressure-sensitive adhesive layer exclusively in a form after crosslinking reaction.

[0051] The amount of crosslinking agent used can be, for example, in the range of 0.005 parts by weight or more and 10 parts by weight or less per 100 parts by weight of base polymer. The amount of crosslinking agent used per 100 parts by weight of base polymer may be, for example, 0.01 parts by weight or more, 0.1 parts by weight or more, or 0.5 parts by weight or more. Furthermore, from the viewpoint of improving adhesion to the surface of the adherend (object to be processed), the amount of crosslinking agent used per 100 parts by weight of base polymer may be, for example, less than 5.0 parts by weight, less than 4.0 parts by weight, 3.5 parts by weight or less, or 2.5 parts by weight or less. The technology disclosed herein can also be suitably implemented in an embodiment in which the amount of crosslinking agent used per 100 parts by weight of base polymer is less than 2.0 parts by weight or 1.5 parts by weight or less.

[0052] Examples of crosslinking agents that can be used include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, peroxide-based crosslinking agents, and the like. Preferred examples of the crosslinking agents include isocyanate-based crosslinking agents and epoxy-based crosslinking agents. The crosslinking agents can be used alone or in combination of two or more. In some embodiments, isocyanate-based crosslinking agents can be preferably used. The isocyanate-based crosslinking agents can be used alone or in combination of two or more. The isocyanate-based crosslinking agent may be used in combination with another crosslinking agent, for example, an epoxy-based crosslinking agent.

[0053] The isocyanate crosslinking agent can be a compound having two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate group is temporarily protected by a blocking agent or oligomerization, etc.) per molecule. Examples of the isocyanate crosslinking agent include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

[0054] More specifically, examples of the isocyanate crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate and isophorone diisocyanate, aromatic diisocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate and polymethylene polyphenyl isocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name: Coronate L), trimethylolpropane / hexamethylene diisocyanate trimer adduct (manufactured by Tosoh Corporation, trade name: Coronate HL), and isocyanurate of hexamethylene diisocyanate (manufactured by Tosoh Corporation). Examples of suitable isocyanate adducts include those manufactured by Thor Chemicals under the trade name of Coronate HX, trimethylolpropane adduct of xylylene diisocyanate (manufactured by Mitsui Chemicals, Inc. under the trade name of Takenate D110N), trimethylolpropane adduct of xylylene diisocyanate (manufactured by Mitsui Chemicals, Inc. under the trade name of Takenate D120N), trimethylolpropane adduct of isophorone diisocyanate (manufactured by Mitsui Chemicals, Inc. under the trade name of Takenate D140N), trimethylolpropane adduct of hexamethylene diisocyanate (manufactured by Mitsui Chemicals, Inc. under the trade name of Takenate D160N), polyether polyisocyanates, polyester polyisocyanates, and adducts of these with various polyols, and polyisocyanates multifunctionalized with isocyanurate bonds, biuret bonds, allophanate bonds, etc. Among these, aromatic isocyanates and alicyclic isocyanates are preferred.

[0055] The amount of the isocyanate crosslinking agent used may be, for example, about 0.1 parts by weight or more, about 0.5 parts by weight or more, about 1.0 parts by weight or more, or even more than 1.5 parts by weight, per 100 parts by weight of the base polymer. From the viewpoint of obtaining a higher usage effect, in some preferred embodiments of the pressure-sensitive adhesive layer, the amount of the isocyanate crosslinking agent used per 100 parts by weight of the base polymer may be, for example, more than 2.0 parts by weight, about 2.5 parts by weight or more, more than 2.5 parts by weight, or about 2.7 parts by weight or more. Furthermore, the amount of the isocyanate crosslinking agent used per 100 parts by weight of the base polymer may be, for example, 10 parts by weight or less, 7 parts by weight or less, or 5 parts by weight or less.

[0056] As the epoxy-based crosslinking agent, a polyfunctional epoxy compound having two or more epoxy groups in one molecule can be used. Examples of the epoxy-based crosslinking agent include N,N,N',N'-tetraglycidyl-m-xylylenediamine, diglycidylaniline, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, and sorbitol polyglycidyl ether. Examples of epoxy crosslinking agents include glycerol, glycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitan polyglycidyl ether, trimethylolpropane polyglycidyl ether, adipic acid diglycidyl ester, o-phthalic acid diglycidyl ester, triglycidyl-tris(2-hydroxyethyl)isocyanurate, resorcinol diglycidyl ether, bisphenol-S-diglycidyl ether, and epoxy resins having two or more epoxy groups in the molecule. Commercially available epoxy crosslinking agents include, for example, "Tetrad C" and "Tetrad X" manufactured by Mitsubishi Gas Chemical Company, Inc.

[0057] The epoxy-based crosslinking agent can be used alone or in combination with two or more types. The epoxy-based crosslinking agent may be used alone or in combination with another crosslinking agent, such as an isocyanate-based crosslinking agent. The amount of the epoxy-based crosslinking agent used can be, for example, about 0.005 to 5 parts by weight, or may be 0.01 to 5 parts by weight, or may be 0.1 to 3 parts by weight, per 100 parts by weight of the base polymer.

[0058] In addition, the pressure-sensitive adhesive layer may contain, as necessary, various additives commonly used in the field of pressure-sensitive adhesives, such as crosslinking aids, plasticizers, softeners, fillers, antistatic agents, antioxidants, ultraviolet absorbers, antioxidants, light stabilizers, etc. As such additives, conventionally known ones can be used in the usual manner, and they do not particularly characterize the present invention, so detailed explanations thereof will be omitted.

[0059] The method for providing such a pressure-sensitive adhesive layer on the first surface of the substrate is not particularly limited. For example, known methods can be appropriately employed, such as a method in which a pressure-sensitive adhesive composition containing pressure-sensitive adhesive layer-forming components in an appropriate medium (e.g., a solution in which the pressure-sensitive adhesive layer-forming components are dissolved in an organic solvent, or a dispersion in which the components are dispersed in an aqueous solvent) is applied to the substrate and dried or cured to form a pressure-sensitive adhesive layer directly on the substrate; a method in which a pressure-sensitive adhesive layer formed on a surface having releasability is transferred to the substrate; or a method in which the pressure-sensitive adhesive layer-forming components are melt-heated together with the substrate-forming components and laminated by co-extrusion molding. To form a pressure-sensitive adhesive layer that constitutes a pressure-sensitive adhesive sheet with higher high-speed peel strength, a method in which a pressure-sensitive adhesive composition is applied is preferably employed from the viewpoint of ease of handling of the pressure-sensitive adhesive layer-forming components. The pressure-sensitive adhesive composition can be prepared, for example, by mixing a polymer component, typically a tackifier, other components used as necessary, and the medium using a conventional method. Various conventionally known methods can be used to apply the pressure-sensitive adhesive composition. Specific examples of the coating method include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and extrusion coating using a die coater or the like.

[0060] (gel fraction) The pressure-sensitive adhesive layer disclosed herein preferably has a gel fraction of a predetermined value or higher. A pressure-sensitive adhesive layer with too low a gel fraction tends to leave the pressure-sensitive adhesive on the surface of the adherend after the processing of the object to be processed (adherend) and the peeling off of the unnecessary pressure-sensitive adhesive sheet (so-called "adhesive residue"). From the viewpoints of suppressing adhesive residue and exhibiting good adhesive properties, the gel fraction of the pressure-sensitive adhesive layer is usually 10% or higher, preferably 15% or higher, more preferably 17% or higher, even more preferably 20% or higher, and particularly preferably 25% or higher, and may be 28% or higher, 30% or higher, or even 32% or higher. From the viewpoints of improving adhesion to the adherend and improving adhesive strength, the gel fraction is usually 70% or lower, preferably less than 60%, more preferably 55% or lower, even more preferably 50% or lower, and may be 40% or lower, 38% or lower, or 35% or lower. The gel fraction can be adjusted by the molecular weight, molecular structure, concentration, degree of crosslinking, etc. of the base polymer. The gel fraction is measured by the following method, which is also used in the examples described below.

[0061] [Gel fraction] A predetermined amount of adhesive sample (weight Wg1) is wrapped in a porous polytetrafluoroethylene membrane (weight Wg2) with an average pore size of 0.2 μm, and the opening is tied with string (weight Wg3). The porous polytetrafluoroethylene (PTFE) membrane is available from Nitto Denko Corporation under the trade name "Nitoflon (registered trademark) NTF1122" (average pore size 0.2 μm, porosity 75%, thickness 85 μm) or an equivalent. The package is immersed in a sufficient amount of ethyl acetate and kept at room temperature (typically 23°C) for 7 days to elute only the sol component in the adhesive layer outside the film, and then the package is taken out and the ethyl acetate adhering to the outer surface is wiped off, and the package is dried at 130°C for 2 hours, and the weight of the package (Wg4) is measured. The gel fraction of the adhesive layer can be calculated by substituting each value into the following formula. Gel fraction (%) = [(Wg4 - Wg2 - Wg3) / Wg1] x 100

[0062] The thickness of the pressure-sensitive adhesive layer can be appropriately set so as to obtain appropriate adhesive performance depending on the application of the pressure-sensitive adhesive sheet. The thickness of the pressure-sensitive adhesive layer is usually suitably set to 0.5 μm to 50 μm. From the viewpoint of improving adhesion to the adherend, in some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 1.5 μm or more, 3 μm or more, 5 μm or more, 7 μm or more, or 10 μm or more. Furthermore, the thickness of the pressure-sensitive adhesive layer may be, for example, 30 μm or less, 20 μm or less, 18 μm or less, 16 μm or less, or 15 μm or less. A small thickness of the pressure-sensitive adhesive layer can be advantageous, for example, in a pressure-sensitive adhesive sheet that can be used in an embodiment in which it is laser-cut together with the adherend (workpiece), from the viewpoint of speed and precision of laser processing.

[0063] <Adhesive sheet> The adhesive sheet disclosed herein is an adhesive sheet comprising a resin film as a substrate and an adhesive layer provided on a first surface of the substrate. The adhesive sheet has excellent high-speed peel strength against stainless steel (SUS) plates. Furthermore, the adhesive sheet is characterized by having excellent high-speed peel strength even against a polishing plate (hereinafter simply referred to as "polishing plate") having polishing residues attached to its surface.

[0064] (High-speed peel strength (against polished plate)) The adhesive sheet disclosed herein preferably has a high-speed peel strength (against the polishing plate) of 2.0 N / 10 mm or more when measured 30 minutes after being attached to the polishing plate at a tensile speed of 30 m / min. Here, a tensile speed of 30 m / min is a measurement condition set assuming a situation in which an assist gas is blown onto the adhesive sheet attached to the workpiece when the workpiece is processed, for example, with a short-wavelength laser beam. If the assist gas supplied during laser processing causes the adhesive sheet to float (typically, partial peeling occurs when the assist gas enters the adhesive interface between the workpiece and the adhesive sheet due to the wind pressure from the cut portion caused by the laser beam), the adhesive sheet will be exposed to heat in a state in which it is no longer fixed to the workpiece (bonded by the adhesive), resulting in increased thermal shrinkage, which can lead to inconveniences such as the surface of the workpiece being more likely to be exposed on both sides of the cut portion. An adhesive sheet with a high-speed peel strength (against abrasive plate) of 2.0 N / 10 mm or more can effectively prevent the adhesive sheet from lifting when cut, even when applied to a workpiece with abrasive residue adhering to its surface.

[0065] The high-speed peel strength (against polished plate) can be measured by the following method. Specifically, the surface of a stainless steel (SUS304) plate is buffed, and after polishing, the polished surface is wiped with a dry cloth to prepare a polished plate as an adherend. Buffing can be performed using a No. 400 buff together with an abrasive. In preparing the polished plate, the polished surface after polishing is not intentionally washed with a solvent or the like. Therefore, residues from the abrasives used in polishing adhere to the surface of the polished plate. The polished plate as an adherend used in measuring the low-speed peel strength (against polished plate) described below is prepared in the same manner. The adhesive sheet is cut into strips measuring 10 mm wide and 100 mm long to prepare test specimens. The adhesive surface of the test specimen is pressed against a polished plate as an adherend by rolling a 2 kg rubber roller specified in JIS Z0237:2000 back and forth once. The sample is left for 30 minutes under a standard environment of 23°C and 50% RH, and then the peel strength (unit: N / 10 mm) is measured under the same standard environment using a universal tensile tester at a tensile speed of 30 m / min and a peel angle of 180°. A universal tensile / compression tester (TCM-1kNB, manufactured by Minebea Co., Ltd.) can be used as the tensile tester.

[0066] From the viewpoint of obtaining a higher effect, in some embodiments, the high-speed peel strength (against abrasive plate) of the PSA sheet may be, for example, 2.4 N / 10 mm or more, 3.5 N / 10 mm or more, 4.5 N / 10 mm or more, 5.5 N / 10 mm or more, or 6.0 N / 10 mm or more. There is no particular upper limit to the high-speed peel strength (against abrasive plate). However, from the viewpoint of reducing the workload when peeling the PSA sheet from the workpiece and preventing the PSA sheet from tearing, in some embodiments, the high-speed peel strength (against abrasive plate) of the PSA sheet may be, for example, 20 N / 10 mm or less, 15 N / 10 mm or less, 10 N / 10 mm or less, 8.0 N / 10 mm or less, or 7.0 N / 10 mm or less. The high-speed peel strength (against abrasive plate) is specifically measured by the method described in the Examples below. The high-speed peel strength (against abrasive plate) can be adjusted, for example, by selecting the type and thickness of the adhesive layer, selecting the type and amount of crosslinking agent used, selecting the type and amount of release agent used, or using optional components such as a tackifying resin.

[0067] (High-speed peel strength (against SUS plate)) The pressure-sensitive adhesive sheet disclosed herein preferably has a high-speed peel strength (vs. SUS plate) of 2.0 N / 10 mm or more, measured 30 minutes after application to a stainless steel (SUS) plate at a tensile speed of 30 m / min. Pressure-sensitive adhesive sheets with high high-speed peel strength (vs. SUS plate) tend to be able to effectively prevent the pressure-sensitive adhesive sheet from lifting when cut. From the viewpoint of achieving a higher effect, in some embodiments, the high-speed peel strength (vs. SUS plate) of the pressure-sensitive adhesive sheet may be, for example, 2.5 N / 10 mm or more, 3.0 N / 10 mm or more, or even 3.5 N / 10 mm or more. There is no particular upper limit to the high-speed peel strength (vs. SUS plate). However, from the viewpoint of reducing the workload when peeling the pressure-sensitive adhesive sheet from the workpiece and preventing the pressure-sensitive adhesive sheet from tearing, in some embodiments, the high-speed peel strength (vs. SUS plate) of the pressure-sensitive adhesive sheet may be, for example, 10 N / 10 mm or less, 9.5 N / 10 mm or less, 9.0 N / 10 mm or less, or 8.5 N / 10 mm or less. The high-speed peel strength (against SUS plate) can be adjusted, for example, by selecting the type and thickness of the pressure-sensitive adhesive layer, selecting the type and amount of crosslinking agent used, selecting the type and amount of release agent used, or using optional components such as a tackifying resin.

[0068] The high-speed peel strength (against SUS plate) can be measured by the following method. Specifically, a test piece is prepared by cutting the pressure-sensitive adhesive sheet into a strip measuring 10 mm wide and 100 mm long. The adhesive surface of this test piece is pressed against a stainless steel plate (SUS304BA plate) as an adherend by rolling it back and forth once using a 2 kg rubber roller specified in JIS Z0237:2000. The sample is left for 30 minutes under a standard environment of 23°C and 50% RH, and then the peel strength (unit: N / 10 mm) is measured under the same standard environment at a tensile speed of 30 m / min and a peel angle of 180° using a universal tensile tester. A universal tensile / compression tester (model name "Tension / Compression Tester, TCM-1kNB" manufactured by Minebea Co., Ltd.) can be used as the tensile tester. The stainless steel plate (SUS304BA plate) used as the adherend has been cleaned using the method specified in JIS Z0237:2000. The same applies to the stainless steel plate (SUS304BA plate) used as the adherend in the measurement of low-speed peel strength (against SUS plate) described later.

[0069] The pressure-sensitive adhesive sheet disclosed herein has excellent low-speed peel strength against stainless steel (SUS) plates, and furthermore, the pressure-sensitive adhesive sheet has excellent low-speed peel strength even against SUS plates having polishing residues attached to the surface.

[0070] (Low speed peel strength (against polished plate)) The adhesive sheet disclosed herein preferably has a low-speed peel strength (against polishing plate) of 1.0 N / 10 mm or more, measured 30 minutes after application to the polishing plate at a tensile speed of 0.3 m / min. An adhesive sheet having a low-speed peel strength (against polishing plate) of 1.0 N / 10 mm or more can effectively prevent peeling of the adhesive sheet during post-laser processing (e.g., bending, drilling, etc.).

[0071] The low-speed peel strength (against abrasive plate) can be measured by the following method. Specifically, a test piece is prepared by cutting the pressure-sensitive adhesive sheet into a strip measuring 10 mm wide and 100 mm long. The adhesive surface of this test piece is pressed against abrasive plate (adherend) by rolling a 2 kg rubber roller specified in JIS Z0237:2000 back and forth once. The sample is left for 30 minutes under a standard environment of 23°C and 50% RH, and then the peel strength (unit: N / 10 mm) is measured under the same standard environment at a tensile speed of 0.3 m / min and a peel angle of 180° using a universal tensile tester. A universal tensile / compression tester (TCM-1kNB, manufactured by Minebea Co., Ltd.) can be used as the tensile tester.

[0072] In some embodiments, the low-speed peel strength (against abrasive plate) of the PSA sheet may be, for example, 1.1 N / 10 mm or more, 1.2 N / 10 mm or more, 1.3 N / 10 mm or more, 1.4 N / 10 mm or more, 1.5 N / 10 mm or more, or 1.6 N / 10 mm or more. There are no particular upper limits to the low-speed peel strength (against abrasive plate), but from the viewpoint of reducing the effort required to peel off an unnecessary PSA sheet after processing an object to be processed (adherend) and improving workability, and from the viewpoint of preventing PSA from adhering to the surface of the adherend after peeling the PSA sheet (so-called "adhesive residue"), in some embodiments, the low-speed peel strength (against abrasive plate) of the PSA sheet may be, for example, 10 N / 10 mm or less, 5.0 N / 10 mm or less, 3.0 N / 10 mm or less, 2.0 N / 10 mm or less, or 1.8 N / 10 mm or less. The low-speed peel strength (against abrasive plate) is specifically measured by the method described in the Examples below. The low-speed peel strength (against abrasive plate) can be adjusted, for example, by selecting the type and thickness of the pressure-sensitive adhesive layer, the type and amount of crosslinking agent used, the type and amount of release agent used, or the use of optional components such as a tackifying resin.

[0073] (Low speed peel strength (against SUS plate)) The pressure-sensitive adhesive sheet disclosed herein preferably has a low-speed peel strength (vs. SUS plate) of 0.5 N / 10 mm or more, measured 30 minutes after application to a stainless steel (SUS) plate at a tensile speed of 0.3 m / min. Pressure-sensitive adhesive sheets with high low-speed peel strength (vs. SUS plate) tend to be able to effectively prevent peeling of the pressure-sensitive adhesive sheet during subsequent processes such as bending or drilling. From the viewpoint of achieving even greater effectiveness, in some embodiments, the low-speed peel strength (vs. SUS plate) of the pressure-sensitive adhesive sheet may be, for example, 1.0 N / 10 mm or more, 1.5 N / 10 mm or more, or 2.0 N / 10 mm or more. Although there is no particular upper limit to the low-speed peel strength (against SUS plate), from the viewpoint of reducing the effort required to peel off an unnecessary PSA sheet after processing an object to be processed (adherend) and improving workability, and from the viewpoint of suppressing adhesive residue on the adherend surface after peeling the PSA sheet, in some embodiments, the low-speed peel strength (against SUS plate) of the PSA sheet may be, for example, 10 N / 10 mm or less, 8.0 N / 10 mm or less, 6.0 N / 10 mm or less, or 5.0 N / 10 mm or less. The low-speed peel strength (against SUS plate) can be adjusted, for example, by selecting the type and thickness of the PSA layer, the type and amount of crosslinking agent used, the type and amount of release agent used, the use of optional components such as a tackifying resin, etc.

[0074] The low-speed peel strength (against SUS plate) can be measured by the following method. Specifically, a test piece is prepared by cutting the pressure-sensitive adhesive sheet into a strip measuring 10 mm wide and 100 mm long. The adhesive surface of this test piece is pressed against a stainless steel plate (SUS304BA plate) as an adherend by rolling a 2 kg rubber roller specified in JIS Z0237:2000 back and forth once. This sample is left for 30 minutes under a standard environment of 23°C and 50% RH, and then the peel strength (unit: N / 10 mm) is measured under the same standard environment using a universal tensile tester at a tensile speed of 0.3 m / min and a peel angle of 180°. A universal tensile / compression tester (TCM-1kNB, manufactured by Minebea Co., Ltd.) can be used as the tensile tester.

[0075] In some embodiments of the pressure-sensitive adhesive sheet disclosed herein, the pressure-sensitive adhesive sheet preferably has a laser light absorptance of 20% or more in the wavelength range of the laser light used for processing (typically, the laser light absorptance at the main wavelength of the laser light). This laser light absorptance refers to the proportion of laser light that is actually absorbed by the pressure-sensitive adhesive sheet out of the laser light irradiated onto the pressure-sensitive adhesive sheet. A pressure-sensitive adhesive sheet with a laser light absorptance of 20% or more can efficiently absorb laser light.

[0076] In some embodiments, the laser light absorptivity of the pressure-sensitive adhesive sheet may be, for example, 25% or more, 30% or more, 45% or more, 60% or more, or 75% or more. The laser light absorptivity of the pressure-sensitive adhesive sheet may be 100%, but in practice, 95% or less is preferred, and may be 90% or less.

[0077] In this specification, the term "laser light absorptance" refers to a value calculated from the transmittance T (%) and reflectance R (%) of a sample measured using a spectrophotometer (for example, a spectrophotometer manufactured by Hitachi High-Technologies Corporation, model "U-4100" or an equivalent), using the following formula (I): Absorption rate A (%) = 100 (%) - T (%) - R (%) (I)

[0078] In this specification, for example, "laser light absorptance in the wavelength range of 900 nm to 1100 nm" refers to the minimum laser light absorptance in that wavelength range. Furthermore, unless otherwise specified, laser light absorptance in this specification refers to the laser light absorptance on the back side of the adhesive sheet or substrate (the side on which the laser light is irradiated, i.e., the side opposite the side attached to the workpiece).

[0079] The transmittance and reflectance of the pressure-sensitive adhesive sheet are not particularly limited. In some embodiments, the pressure-sensitive adhesive sheet may have a laser light transmittance of less than 70%, for example, less than 50%, at the wavelength at which the laser light absorptance is minimum within the wavelength range of the laser light used for processing. In some embodiments, the pressure-sensitive adhesive sheet may have a laser light reflectance of less than 50%, for example, less than 40%, less than 20%, or less than 10%, at the wavelength at which the laser light absorptance is minimum. Pressure-sensitive adhesive sheets that satisfy at least one of the above transmittance and reflectance (preferably both) tend to have the preferred laser light absorptance disclosed herein.

[0080] In order to adjust the laser beam absorption rate, a laser beam absorbent can be used as needed. As the laser beam absorbent, various materials that can exhibit the effect of increasing the absorption rate of the laser beam used in processing (typically, the absorption rate at least at the main wavelength) can be preferably used. The type of laser beam absorbent contained in the pressure-sensitive adhesive sheet may be one type, or two or more types. In a pressure-sensitive adhesive sheet containing two or more types of laser beam absorbents, the laser beam absorbents may be used as a blend, or may be contained in different layers within the pressure-sensitive adhesive sheet.

[0081] In this specification, the term "laser beam absorbent" refers to a material that can increase the laser beam absorption rate compared to when the laser beam absorbent is not used. In addition, in this specification, the term "specific absorbent" refers to the above-mentioned laser beam absorbent that contains, as a constituent element, a metal with a specific heat of less than 900 J / kg·K and a thermal conductivity of less than 200 W / m·K. In this specification, a layer containing a laser beam absorbent (which may be a specific absorbent) may be referred to as a "laser beam absorbing layer."

[0082] Examples of laser beam absorbents that can be used in the pressure-sensitive adhesive sheet disclosed herein include metals such as aluminum, stainless steel, titanium, nickel, zirconium, tungsten, copper, silver, gold, zinc, molybdenum, chromium, and alloys containing these as main components; metal compounds such as oxides, nitrides, and carbides of the above metals (e.g., titanium oxide, aluminum oxide, etc.); carbon materials such as carbon black and carbon fiber; organic compounds such as phthalocyanine compounds, cyanine compounds, aminium compounds, naphthalocyanine compounds, naphthoquinone compounds, diimonium compounds, anthraquinone compounds, and aromatic dithiol metal complexes (e.g., nickel complexes); etc. In a laser beam absorbing layer containing a laser beam absorbent in a resin composition, it is preferable to use a material with a higher thermal decomposition temperature than the resin component constituting the laser beam absorbing layer as the laser beam absorbent.

[0083] When a powdered laser beam absorbent is used, the shape of the particles constituting the powder is not particularly limited and may be, for example, flaky, spherical, acicular, polyhedral, irregular, or the like. Typically, a flaky, spherical, or acicular laser beam absorbent is preferably employed. The average particle size of the laser beam absorbent is not particularly limited and may be, for example, 0.005 μm or more and 20 μm or less. From the viewpoint of dispersibility, typically, a laser beam absorbent having an average particle size of 10 μm or less or 5 μm or less is preferably used. From the viewpoint of efficiently increasing the laser beam absorptance with a small amount of laser beam absorbent, in some embodiments, the average particle size of the laser beam absorbent may be, for example, 3 μm or less, 1 μm or less, 0.6 μm or less, 0.4 μm or less, or 0.3 μm or less. Furthermore, from the viewpoint of powder handling ease and ease of uniform dispersion, in some embodiments, the average particle size of the laser beam absorbent may be, for example, 0.008 μm or more, 0.01 μm or more, 0.05 μm or more, 0.1 μm or more, 0.15 μm or more, or 0.2 μm or more. In this specification, unless otherwise specified, the term "average particle size" refers to the particle size at 50% of the cumulative value in the particle size distribution measured with a particle size distribution measuring device based on a laser scattering / diffraction method (50% volume average particle size).

[0084] In some embodiments, the laser beam absorbing layer may contain carbon black as the laser beam absorbent. For example, carbon black having an average particle size of 10 nm to 500 nm (more preferably 10 nm to 120 nm) may be used. Carbon black may be used alone or in combination with other laser beam absorbents.

[0085] In some embodiments, the laser beam absorbing layer may contain at least one of a metal powder and a metal compound powder as a laser beam absorbent. Such a laser beam absorbent is preferable because it can withstand heat generation accompanying absorption of the specific laser beam and appropriately maintain the property of absorbing the specific laser beam. Suitable examples of this type of laser beam absorbent include titanium oxide powder, aluminum oxide powder, and metallic aluminum powder.

[0086] The laser beam absorbing layer is typically a layer containing a laser beam absorbent in a resin component. Non-limiting examples of materials that can be used as such a resin component include polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and polypropylene-polyethylene blend resin; and vinyl chloride resins, vinyl acetate resins, polyamide resins, and the like. The laser beam absorbing layer can be formed by molding a resin composition obtained by blending a laser beam absorbent with such a resin material into a typically film-like shape.

[0087] When a laser beam absorbent is used, the amount used is not particularly limited. In some embodiments, the amount of the laser beam absorbent used may be, for example, 0.01 wt % or more, 0.05 wt % or more, or 0.1 wt % or more of the laser beam absorbing layer containing the laser beam absorbent. Furthermore, from the viewpoint of reducing laser cutting residues and suppressing reflectance, in some embodiments, the content of the laser beam absorbent in the laser beam absorbing layer containing the laser beam absorbent may be, for example, 10 wt % or less, 5 wt % or less, 3 wt % or less, or 2 wt % or less.

[0088] In some embodiments, the PSA sheet disclosed herein may preferably use, as the laser beam absorbent, a specific absorbent, i.e., a laser beam absorbent having as a constituent element a metal with a specific heat of less than 900 J / kg·K and a thermal conductivity of less than 200 W / m·K. The specific absorbent may be selected from the group consisting of: a simple metal of any one of the metals satisfying the above specific heat and thermal conductivity; an alloy containing more than 50 wt%, more than 70 wt%, or more than 90 wt% of a metal satisfying the above specific heat and thermal conductivity; an alloy containing two or more metals satisfying the above specific heat and thermal conductivity in a total amount of more than 50 wt%, more than 70 wt%, or more than 90 wt%; a metal compound containing, as a constituent element, a metal corresponding to such a simple metal or alloy; and the like. Examples of specific absorbents include iron, iron alloys (e.g., iron alloys containing at least one element selected from the group consisting of Cr, Ni, Si, W, Mn, Si, and C), and metal compounds (iron-based compounds) containing, as a constituent element, a metal corresponding to the iron or iron alloy (an iron-based metal). Preferred examples of the iron-based compounds include oxides of the iron-based metals (iron-based oxides). Other examples of specific absorbents include Mn-based compounds containing, as a constituent element, a metal corresponding to Mn or a Mn alloy (a Mn-based metal), with Mn-based oxides being preferred. The specific absorbents can be used alone or in combination of two or more. In a pressure-sensitive adhesive sheet containing two or more types of specific absorbents, the specific absorbents may be blended or may be contained in different layers within the pressure-sensitive adhesive sheet.

[0089] Generally, the specific heat and thermal conductivity of a metal compound containing a metal as a constituent element tend to be smaller than those of a single metal. Therefore, in some embodiments of the pressure-sensitive adhesive sheet disclosed herein, a metal compound containing a metal as a constituent element that satisfies the preferred specific heat and thermal conductivity disclosed herein can be preferably used as a specific absorbent. Metal compounds that can be used as specific absorbents include, for example, oxides, sulfides, carbides, nitrides, hydroxides, oxyhydroxides, etc. of metals that satisfy the preferred specific heat and thermal conductivity disclosed herein. Other examples of metal compounds that can be used as specific absorbents include metal organic compounds (complexes, etc.) containing ions of the metal. From the viewpoint of withstanding the heat generated by absorbing specific laser light and appropriately maintaining the property of absorbing the specific laser light, oxides, sulfides, carbides, and nitrides of the above metals are preferred, and oxides are particularly preferred. Examples of the oxides include iron oxides (FeO, Fe3O4, Fe2O3, etc.), manganese dioxide, titanium black, chromium oxides (CrO, Cr2O3, etc.), ferrite, etc., and examples of the sulfides include iron sulfide, molybdenum sulfide, etc., but are not limited to these.

[0090] When the PSA sheet disclosed herein contains a specific absorbent, the content of the specific absorbent is not particularly limited and can be appropriately selected, for example, from a range of 0.01 wt % to 20 wt % of the PSA sheet. In some embodiments, the content of the specific absorbent may be, for example, 0.05 wt % or more, 0.1 wt % or more, 0.3 wt % or more, 0.5 wt % or more, or 0.8 wt % or more. As the content of the specific absorbent increases, the absorption rate of the specific laser light tends to increase. On the other hand, if the content of the specific absorbent is too high, the energy of the absorbed specific laser light tends to diffuse in the plane direction, which may result in increased energy loss. From this perspective, the content of the specific absorbent is usually 15 wt % or less of the PSA sheet, preferably 10 wt % or less, more preferably 7 wt % or less, and may be 5 wt % or less or less than 5 wt %.

[0091] The PSA sheet disclosed herein may, in addition to the specific absorbent, optionally contain a laser beam absorbent other than the specific absorbent. Hereinafter, such auxiliary laser beam absorbents other than the specific absorbent are also referred to as "auxiliary absorbents." Auxiliary absorbents can be used, for example, to improve the absorbance of the PSA sheet, adjust the transmittance or reflectance, or adjust the appearance. Examples of auxiliary absorbents that can be used include metals such as aluminum, copper, silver, and gold; metal compounds such as oxides, nitrides, and carbides of the above metals; carbon black; and organic compounds such as phthalocyanine compounds, cyanine compounds, aminium compounds, naphthalocyanine compounds, naphthoquinone compounds, diimonium compounds, and anthraquinone compounds.

[0092] The amount of auxiliary absorbent used is preferably less than 50% by weight of the total amount of laser beam absorbent contained in the pressure-sensitive adhesive sheet (i.e., the total amount of the specific absorbent and auxiliary absorbent), and may be less than 25%, less than 10%, or less than 5%. The pressure-sensitive adhesive sheet may also be substantially free of auxiliary absorbent. Here, "substantially free of auxiliary absorbent" means that auxiliary absorbent is not used at least intentionally. The total amount of laser beam absorbent contained in the pressure-sensitive adhesive sheet is suitably 25% by weight or less of the pressure-sensitive adhesive sheet, and more preferably 20% by weight or less, 15% by weight or less, or 10% by weight or less.

[0093] When the PSA sheet disclosed herein contains a specific absorbent, the carbon black (CB) content of the PSA sheet is preferably less than 0.3 wt %, more preferably less than 0.1 wt %, even more preferably less than 0.05 wt %, and particularly preferably 0.02 wt % or less. Reducing the CB content tends to improve the non-contaminating properties of the PSA sheet. The PSA sheet may be substantially free of CB, i.e., a PSA sheet in which CB is not used at least intentionally. By containing a specific absorbent, the PSA sheet disclosed herein can efficiently process workpieces even without using CB or with the amount of CB used limited as described above. Such a PSA sheet can advantageously achieve both improved workpiece processing efficiency and non-contaminating properties.

[0094] In some embodiments, a black metal compound may be preferably used as the specific absorbent. The use of a black metal compound can efficiently increase the laser light absorption rate of the pressure-sensitive adhesive sheet. This makes it possible to preferably achieve a pressure-sensitive adhesive sheet having the above-mentioned preferred laser light absorption rate even if CB is not used or the amount used is limited. The inventors' studies have surprisingly revealed that such black metal compounds, unlike CB, are less likely to produce black residues. Therefore, the use of a black metal compound can preferably achieve both improved workpiece processing efficiency and non-contamination.

[0095] Examples of black metal compounds include, but are not limited to, iron oxide, manganese dioxide, titanium black, chromium oxide, iron sulfide, molybdenum sulfide, etc. Iron oxide (e.g., FeO, Fe3O4, etc.), titanium black, manganese dioxide, etc. are preferred black metal compounds from the viewpoint of availability. The titanium black is black particles containing titanium atoms, and is preferably black particles such as titanium oxynitride or low-order titanium oxide. Among these, iron oxide and titanium black are preferred black metal compounds.

[0096] The content of the black metal compound in the pressure-sensitive adhesive sheet can be, for example, 0.05% by weight or more of the pressure-sensitive adhesive sheet, and from the viewpoint of improving laser light absorption, it may be 0.1% by weight or more, 0.3% by weight or more, 0.5% by weight or more, or 0.8% by weight or more. Furthermore, from the viewpoint of reducing energy loss due to diffusion in the plane direction of the pressure-sensitive adhesive sheet, the content of the black metal compound is usually suitably 15% by weight or less of the pressure-sensitive adhesive sheet, preferably 10% by weight or less, more preferably 7% by weight or less, and may be 5% by weight or less or less than 5% by weight. The proportion of the black metal compound in the specific absorber may be, for example, more than 50% by weight, 70% by weight or more, 90% by weight or more, or substantially 100% by weight.

[0097] Brightness L of the back of the adhesive sheet * Preferably, the lightness L of the back surface of the pressure-sensitive adhesive sheet is less than 95. * For example, the lightness L of the back surface may be less than 90, less than 70, less than 60, less than 50, less than 45, or less than 40. * By setting the lightness L low, it becomes easier to increase the laser light absorption rate of the adhesive sheet. * The lower limit of the brightness L of the back surface of the PSA sheet is not particularly limited, but from the viewpoint of the design, surface printability, weather resistance, and identifiability of the PSA sheet, it is usually appropriate to set the brightness L to 20 or more, and may be set to 30 or more. * may be, for example, 40 or more, or 50 or more.

[0098] Chromaticity a of the back of the adhesive sheet * In some embodiments, the lightness L * From the same viewpoint, the chromaticity a of the back of the adhesive sheet * The chromaticity b of the back surface of the pressure-sensitive adhesive sheet may be, for example, in the range of -15 to +15, -10 to +10, -5 to +7, -3 to +5, -1.5 to +3, or 0 to +2. *is not particularly limited, and may be, for example, in the range of -15 to +15, -10 to +10, -5 to +5, -3 to +2, or -1.5 to +1.

[0099] Brightness L of the front surface of the adhesive sheet * , chromaticity a * , chromaticity b * is the brightness L of the back surface of the adhesive sheet mentioned above. * , chromaticity a * , chromaticity b * The lightness L can be appropriately selected from the same range as above. * , chromaticity a * , chromaticity b * Each of the above may be the same on the front and back surfaces of the pressure-sensitive adhesive sheet, or may be different.

[0100] In this specification, the lightness L * , chromaticity a * and chromaticity b * L * a * b * Lightness L specified in the color system * , chromaticity a * , chromaticity b * This means that the lightness L is in accordance with the standards recommended by the International Commission on Illumination in 1976 or the standards of JIS Z 8729. * , chromaticity a * , chromaticity b * The lightness L can be measured using a color difference meter (for example, a Minolta color difference meter under the trade name "CR-400"). * , chromaticity a * , chromaticity b * can be adjusted by selecting the type of laser beam absorbent, selecting the amount of laser beam absorbent used, whether or not a colorant other than the laser beam absorbent is used, and selecting the type and amount of the colorant used when a colorant is used, etc.

[0101] The thickness of the pressure-sensitive adhesive sheet is not particularly limited, but is usually approximately 10 μm to 200 μm. From the viewpoint of the handleability of the pressure-sensitive adhesive sheet, in some embodiments, the thickness of the pressure-sensitive adhesive sheet may be, for example, 20 μm or more, 25 μm or more, 40 μm or more, 55 μm or more, or 80 μm or more. Furthermore, from the viewpoint of, for example, the speed and precision of laser processing, the thickness of the pressure-sensitive adhesive sheet may be, for example, 150 μm or less, 120 μm or less, or 100 μm or less. In some cases, the thickness of the pressure-sensitive adhesive sheet may be 80 μm or less, 60 μm or less, or 50 μm or less.

[0102] <Base material> The pressure-sensitive adhesive sheet disclosed herein includes a resin film as a substrate. Examples of resin materials constituting the resin film include, but are not limited to, polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymers, and polypropylene-polyethylene blend resins; vinyl chloride resins (typically soft vinyl chloride resins), vinyl acetate resins, and polyamide resins.

[0103] In some embodiments, from the viewpoint of various processability due to the flexibility of the substrate, or, for example, from the viewpoint of the cuttability and non-contamination of the adhesive sheet with specific laser light, a polyolefin-based resin film or a polyester-based resin film can be preferably used as the resin film.

[0104] Here, a polyolefin-based resin film refers to a resin film whose main component is a polyolefin-based resin. Unless otherwise specified, the term "main component" in this specification refers to a component that accounts for more than 50% by weight. For example, when a resin film's main component is a polyolefin-based resin, it means that the resin film contains more than 50% by weight of the polyolefin-based resin. A suitable example of a polyolefin-based resin film is a resin film whose main component is a polyethylene (PE) resin and / or a polypropylene (PP) resin. A polyolefin-based resin film may contain PE resin and / or PP resin, with the total amount of PE resin and PP resin accounting for more than 50% by weight of the polyolefin resin film, preferably 70% by weight or more, for example 85% by weight or more. In a resin film that contains PE resin but not PP resin, the total amount corresponds to the PE resin content.

[0105] The PE resin may be primarily composed of various polymers (ethylene-based polymers) containing ethylene as the main constituent monomer unit. It may also be a PE resin substantially composed of one or more ethylene-based polymers. The ethylene-based polymer may be an ethylene homopolymer, or may be a copolymer (random copolymer, block copolymer, etc.) of ethylene as the main monomer with another α-olefin as a secondary monomer. Suitable examples of the α-olefin include α-olefins having 3 to 10 carbon atoms, such as propylene, 1-butene (which may be branched 1-butene), 1-hexene, 4-methyl-1-pentene, and 1-octene. For example, a PE resin primarily composed of an ethylene-based polymer copolymerized with the α-olefin as a secondary monomer at a ratio of 10% by weight or less (typically 5% by weight or less) can be preferably used.

[0106] The PE resin may also be a PE resin containing a copolymer of ethylene with a monomer (functional group-containing monomer) having another functional group in addition to the polymerizable functional group, or a PE resin in which such a functional group-containing monomer is copolymerized with an ethylene polymer. Examples of copolymers of ethylene and functional group-containing monomers include ethylene-vinyl acetate copolymer (EVA), ethylene-acrylic acid copolymer (EAA), ethylene-methacrylic acid copolymer (EMAA), ethylene-methyl acrylate copolymer (EMA), ethylene-ethyl acrylate copolymer (EEA), ethylene-methyl methacrylate copolymer (EMMA), and ethylene-(meth)acrylic acid (i.e., acrylic acid and / or methacrylic acid) copolymers crosslinked with metal ions.

[0107] The density of the PE resin is not particularly limited. The concept of PE resin here includes high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE). In one embodiment, the density of the PE resin is, for example, 0.90 to 0.94 g / cm. 3 Preferred PE resins include LDPE and LLDPE.

[0108] The PP resin may be a polymer (propylene-based polymer) having propylene as the main constituent monomer unit, i.e., a polymer in which more than 50% by weight of all constituent monomer units is propylene as the main component. It may also be a PP resin substantially composed of one or more propylene-based polymers. The concept of propylene-based polymer here includes not only homopolypropylene, but also random copolymers (random polypropylenes) and block copolymers (block polypropylenes) of propylene and other monomers.

[0109] The first surface of the substrate (i.e., the surface on which the pressure-sensitive adhesive layer is provided) may be subjected to an appropriate surface treatment, if necessary, to enhance adhesion to the pressure-sensitive adhesive layer. Examples of surface treatments to enhance adhesion include corona discharge treatment, acid treatment, ultraviolet irradiation treatment, plasma treatment, and application of a primer.

[0110] In a preferred embodiment of the PSA sheet disclosed herein, the second surface of the substrate is a release surface. "The second surface of the substrate is a release surface" typically means that a PSA sheet with the surface (adhesive surface) of the PSA layer provided on the first surface of the substrate in contact with the release surface can be peeled off without leaving any adhesive residue (residual adhesive) on the release surface.

[0111] In some embodiments, the resin composition constituting the second surface (hereinafter also referred to as "second surface forming material") preferably contains a release agent. A substrate having such a second surface can be understood as a substrate having the release agent kneaded into at least the second surface. The second surface forming material may constitute at least the second surface of the substrate, and may, for example, constitute only the second surface side of the substrate, or may constitute the entire substrate.

[0112] As the second surface forming material, a resin composition containing at least a release agent and a resin material can be preferably used. Examples of the resin material include, but are not limited to, the various materials exemplified as the resin material constituting the resin film as the substrate, such as polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT); polyolefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and polypropylene-polyethylene blend resin; and other vinyl chloride resins (typically soft vinyl chloride resins), vinyl acetate resins, and polyamide-based resins.

[0113] Examples of release agents that can be used as a component of the second surface forming material (i.e., release agents for kneading into the second surface) include ethylene-vinyl alcohol copolymers, fatty acid amide-based additives, low-molecular-weight polyolefin waxes, long-chain alkyl-based additives, and silicone-based release agents. The release agents can be used alone or in appropriate combinations of two or more. It is preferable to select a release agent that has good miscibility with the resin component contained in the second surface forming material.

[0114] As the ethylene-vinyl alcohol copolymer, for example, an ethylene-vinyl alcohol copolymer obtained by saponifying a copolymer of ethylene with vinyl acetate, vinyl formate, vinyl propionate, or vinyl acetate can be used. Examples of fatty acid amide additives include saturated fatty acid bisamides, unsaturated fatty acid bisamides, aromatic bisamides, and substituted ureas. More specifically, examples of fatty acid amide additives include methylene bisstearic acid amide, ethylene bisstearic acid amide, ethylene bisoleic acid amide, N,N-dioleyl adipamide, N-stearyl-N'-stearyl urea, and other N-stearyl-N'-stearyl acid amides. These fatty acid amide additives may be used alone or in combination of two or more. As the low molecular weight polyolefin wax, for example, low molecular weight waxes such as polyethylene wax and polypropylene wax can be suitably used. As the long-chain alkyl additive, low molecular weight additives having alkyl chains, such as Peloil (registered trademark) 1010 and Peloil (registered trademark) 1010S (both manufactured by Ipposha Yushi Kogyo Co., Ltd.), can be used appropriately. Examples of silicone-based release agents include silylated polyolefins, silicone resins, silicone alkoxy oligomers, silicone oligomers, silicone master pellets, silicone rubber powders, silicone emulsions, etc. As the silylated polyolefins, for example, silylated polyolefins prepared by the method shown in the examples of JP 2011-26448 A can be used.

[0115] Suitable examples of the release agent for the second surface kneading include the long-chain alkyl additives and silicone-based release agents. Of these, silicone-based release agents are particularly preferred. As the silicone-based release agent, silylated polyolefins are particularly preferred.

[0116] The content of the release agent in the second-surface-forming material is not particularly limited and can be, for example, about 0.01 to 80% by weight of the entire second-surface-forming material. In some embodiments, the content of the release agent in the second-surface-forming material may be, for example, 0.1% by weight or more, 0.3% by weight or more, 0.5% by weight or more, 0.7% by weight or more, or 1% by weight or more. From the viewpoint of compatibility with the resin material, the content of the release agent in the second-surface-forming material may be, for example, 70% by weight or less, 50% by weight or less, 30% by weight or less, or 10% by weight or less.

[0117] The substrate may have a single layer structure or a multilayer structure of two or more layers. In some embodiments, a substrate with a multilayer structure may be preferably used. A substrate with a multilayer structure has the advantage that it is easy to make the first surface and the second surface of the substrate different in function and appearance. In a substrate with a multilayer structure, the types of resin materials constituting each layer may be the same or different. The substrate with a multilayer structure may have, for example, a two-layer to five-layer structure, or may have a two-layer or three-layer structure. In some other embodiments, the substrate may have a single layer structure. A substrate with a single layer structure may be advantageous in terms of the productivity and quality stability of the substrate.

[0118] The method for forming the substrate is not particularly limited, and a conventionally known extrusion molding method, such as inflation extrusion molding or cast molding, can be appropriately adopted. The substrate may be unstretched, or may be stretched uniaxially or biaxially. A multilayer substrate can be obtained by simultaneously molding resin compositions corresponding to each layer (for example, by multilayer inflation molding), by laminating each layer after molding, or by casting another layer on a previously molded layer, either alone or in appropriate combination.

[0119] In some embodiments, the substrate may be a substrate with a multilayer structure of two or more layers, including a back layer formed from the second-surface-forming material described above and a support layer disposed inside the back layer (i.e., closer to the first surface). Hereinafter, the resin composition (i.e., the second-surface-forming material) that forms the back layer in a substrate having such a configuration may be referred to as the "back-layer-forming material." As with the second-surface-forming material described above, a resin composition containing a release agent may be preferably used as the back-layer-forming material. The back-layer-forming material may be, for example, a resin composition containing at least a release agent and a resin material. The release agent that can be used as a component of the back-layer-forming material, the content of the release agent in the back-layer-forming material, and examples of resin materials that can be used as a component of the back-layer-forming material are the same as those for the second-surface-forming material described above, and therefore, redundant explanations will be omitted.

[0120] The support layer may be a layer formed from a resin composition. Hereinafter, the resin composition forming the support layer may be referred to as the "support layer-forming material." Resin components that can be used as constituents of the support layer-forming material include, but are not limited to, polyester resins, polyolefin resins, vinyl chloride resins, vinyl acetate resins, polyamide-based resins, and the like, similar to the resin materials constituting the resin film described above. The support layer-forming material may contain one type selected from such resin materials alone, or an appropriate combination of two or more types. The support layer-forming material may not contain a release agent similar to the release agent that can be used in the second surface-forming material, or it may contain a release agent. In an embodiment in which one surface of the support layer also serves as the first surface of the substrate, it is preferable that the support layer-forming material does not contain a release agent, from the viewpoint of improving the anchoring ability of the pressure-sensitive adhesive layer to the support layer. The resin material constituting the back layer-forming material and the resin material constituting the support layer-forming material may be the same or different. From the viewpoint of adhesion between the back layer and the support layer, in some embodiments, the resin material constituting the back layer-forming material is preferably the same type of resin as the resin material constituting the support layer-forming material.

[0121] A substrate including a back layer and a support layer disposed therein can be obtained, for example, by laminating a support layer-forming material and a back layer-forming material by co-extrusion molding. The support layer-forming material may be co-extruded with the back layer-forming material in the form of a pre-formed base resin film. The number of layers to be laminated in each of the layers is not particularly limited, and the back layer and the support layer may each be a single layer, or may have a multi-layer laminate structure as needed.

[0122] The co-extrusion molding can be any method commonly used for producing films, sheets, etc., and is not particularly limited. Specifically, a two-layer, three-layer, four-layer or more multilayer structure can be formed, and for example, an inflation method, a co-extrusion T-die method, etc. can be used. The use of these co-extrusion molding methods is preferred in terms of cost and productivity.

[0123] In the pressure-sensitive adhesive sheet disclosed herein, a preferred method for forming the second surface as a release surface is to form the second surface of the substrate using a second-surface-forming material containing a release agent in a resin composition, as described above, but this is not limited to this. The second surface of the substrate may be, for example, a release surface formed by applying a release treatment agent to a surface formed from a resin composition that does not contain a release agent. Such surface treatment can be carried out using, for example, a general silicone-based, long-chain alkyl-based, or fluorine-based release treatment agent. The surface formed from a resin composition containing a release agent (i.e., the surface into which the release agent has been incorporated) may also be further surface-treated by applying a release treatment agent.

[0124] The substrate may contain a laser beam absorbent as needed. In some embodiments, the laser beam absorbent preferably includes a specific absorbent. A suitable example of a substrate containing a laser beam absorbent is a substrate containing a laser beam absorbing layer (which may be a specific absorbent). In a multilayer substrate, at least one layer is preferably a laser beam absorbing layer containing a laser beam absorbent. The laser beam absorptivity of the substrate containing a laser beam absorbing layer can be set so that the laser beam absorptivity of the pressure-sensitive adhesive sheet is 20% or more. In some embodiments, the laser beam absorptivity of the substrate may be, for example, 15% or more, typically 20% or more is appropriate, but may also be 25% or more, 30% or more, 45% or more, 60% or more, or 75% or more. The laser beam absorptivity of the substrate may be 100%, but in practice, 95% or less is preferable, and may be 90% or less. The transmittance and reflectance of the substrate may be appropriately selected from the same ranges as the transmittance and reflectance of the pressure-sensitive adhesive sheet described above.

[0125] The laser beam absorbent contained in the substrate can be selected from the above-mentioned examples of laser beam absorbents that can be used in pressure-sensitive adhesive sheets, and can be used alone or in combination of two or more. In an embodiment in which the laser beam absorbent contains a specific absorbent, the specific absorbent can be selected from the above-mentioned examples of specific absorbents that can be used in pressure-sensitive adhesive sheets, and can be used alone or in combination of two or more. The content of the laser beam absorbent and the content of the specific absorbent in the substrate can be determined by the examples of the content of the laser beam absorbent and the content of the specific absorbent in the pressure-sensitive adhesive sheet, respectively.

[0126] Back surface brightness L of the substrate * , chromaticity a * , chromaticity b * is the brightness L of the back surface of the adhesive sheet mentioned above. * , chromaticity a * , chromaticity b * Similarly, the lightness L of the front surface of the substrate can be appropriately selected from the same range. * , chromaticity a * , chromaticity b * is the brightness L of the front surface of the adhesive sheet mentioned above. * , chromaticity a * , chromaticity b * It can be appropriately selected from the same range.

[0127] The substrate may contain any additives as needed, such as flame retardants, antistatic agents, light stabilizers (radical scavengers, ultraviolet absorbers, etc.), and antioxidants.

[0128] The thickness of the substrate is not particularly limited and can be, for example, about 5 μm to 150 μm. From the viewpoint of the handleability of the substrate or a pressure-sensitive adhesive sheet including the substrate, in some embodiments, the thickness of the substrate may be, for example, 15 μm or more, 20 μm or more, 35 μm or more, 50 μm or more, or 75 μm or more. Furthermore, from the viewpoint of the speed and precision of laser processing, in some embodiments, the thickness of the substrate may be, for example, 130 μm or less, 110 μm or less, or 90 μm or less. In some cases, the thickness of the substrate may be 70 μm or less, 50 μm or less, or 40 μm or less.

[0129] In a substrate including a back layer (preferably a back layer made of a resin composition containing a release agent) and a support layer, the thickness of the back layer (if the back layer has a laminated structure, the total thickness of these layers) is not particularly limited. From the viewpoint of facilitating the formation of a back layer with minimal thickness unevenness, the thickness of the back layer is advantageously, for example, 1 μm or more, and may be 3 μm or more, or 5 μm or more. The technology disclosed herein can also be suitably implemented in the form of a pressure-sensitive adhesive sheet including a substrate in which the back layer has a thickness of more than 7 μm, more than 10 μm, more than 15 μm, more than 20 μm, or more than 25 μm. The upper limit of the thickness of the back layer is not particularly limited, as long as it is less than the thickness of the entire substrate including the back layer. The thickness of the back layer of the entire thickness of the substrate can be, for example, 1% or more, 3% or more, 5% or more, or 8% or more, or, for example, 95% or less, 70% or less, 50% or less, 20% or less, or 15% or less. The thickness of the backing layer can be, for example, 60 μm or less, 40 μm or less, 30 μm or less, 20 μm or less, 10 μm or less, etc., depending on the thickness of the entire substrate. Reducing the thickness of the backing layer can be advantageous from the viewpoint of making the pressure-sensitive adhesive sheet thinner.

[0130] From the viewpoints of suppressing unevenness in the thickness of the support layer and of the ease of handling of a preformed resin film when the support layer is used, the thickness of the support layer is usually 5 μm or more, preferably 10 μm or more, and may be 25 μm or more, 40 μm or more, or 60 μm or more. The upper limit of the thickness of the support layer is not particularly limited, as long as it is less than the thickness of the entire substrate including the back layer.

[0131] In a substrate including a laser beam absorbing layer, the thickness of the laser beam absorbing layer (in a substrate including a plurality of laser beam absorbing layers, the total thickness of these layers) may be, for example, 3 μm or more, 5 μm or more, or 10 μm or more. From the viewpoint of speed and precision of laser processing, in some embodiments, the thickness of the laser beam absorbing layer (in other words, the portion where the laser beam absorbent is disposed) of the entire thickness of the substrate may be, for example, 20% or more, 50% or more, 70% or more, or 90% or more. Note that in a substrate consisting of a single layer of a laser beam absorbing layer or a substrate consisting of a plurality of laser beam absorbent layers, the thickness of the laser beam absorbing layer accounts for 100% of the entire thickness of the substrate.

[0132] <Roll body> According to this specification, a roll body can be provided that includes the PSA sheet disclosed herein in a wound form. Such a roll body typically includes a core (winding core) and a PSA sheet wound around the core. The shape of the core is not particularly limited, and may be, for example, a solid cylindrical shape, a hollow cylindrical shape (i.e., a cylindrical shape), a hollow or solid polygonal prism shape, etc. From the viewpoint of improving the handleability of the roll body, a hollow cylindrical or hollow polygonal prism-shaped core can be preferably used. A cylindrical core is particularly preferred.

[0133] The material for the core is not particularly limited, and known materials can be used, such as paper such as cardboard, plastic materials such as PE resin, PP resin, vinyl chloride resin, polyester, epoxy resin, phenolic resin, melamine resin, silicon resin, polyurethane, polycarbonate, and acrylonitrile-butadiene-styrene copolymer resin (ABS resin), composite materials such as fiber-reinforced plastic (FRP), and metal materials such as iron, stainless steel (SUS), and aluminum.

[0134] The outer diameter of the core is not particularly limited. In some embodiments, the outer diameter of the core may be, for example, 30 mm or more, 50 mm or more, 70 mm or more, 80 mm or more, or 85 mm or more. For purposes such as improving productivity, there is a demand for increasing the length of the laminate sheet contained in the roll to reduce the frequency of roll replacement. To increase the length of the laminate sheet contained in the roll, a smaller outer diameter of the core is advantageous. From this perspective, the outer diameter of the core is preferably, for example, 300 mm or less, but may also be 250 mm or less, 200 mm or less, or 180 mm or less. The technology disclosed herein can also be suitably implemented in roll embodiments in which the outer diameter of the core is 150 mm or less, 100 mm or less, or even 95 mm or less. In the case of a winding core having a non-circular cross-sectional shape, the core diameter refers to the diameter of a circle approximating the cross-sectional shape.

[0135] In the case of a hollow core, the thickness of the core (i.e., the thickness of the outer wall) is not particularly limited and can be appropriately set so as to obtain the desired strength, taking into consideration the material and outer diameter of the core, etc. From the viewpoint of reducing the weight of the roll body, the thickness of the core is usually appropriate to be about 2 mm to 15 mm, and preferably about 3 mm to 10 mm.

[0136] The width of the pressure-sensitive adhesive sheet constituting the roll disclosed herein is typically 5 mm or more, for example, 10 mm or more, preferably 20 mm or more, more preferably 30 mm or more, 50 mm or more, 150 mm or more, 300 mm or more, or 500 mm or more. As the width of the pressure-sensitive adhesive sheet increases, the peeling noise generated when the pressure-sensitive adhesive sheet is unwound from the roll tends to generally increase. Therefore, it is particularly meaningful to apply the technology disclosed herein to suppress the generation of peeling noise. Furthermore, from the viewpoint of ease of handling, the width of the pressure-sensitive adhesive sheet is usually approximately 5 m or less, and may be, for example, approximately 4 m or less, approximately 3 m or less, approximately 2 m or less, or approximately 1 m or less.

[0137] In the PSA sheet constituting the roll disclosed herein, the high-speed unwinding force measured at a speed of 30 m / min is, for example, preferably 5 N / 20 mm or less, more preferably 4.5 N / 20 mm or less, and may be 4 N / 20 mm or less. A small high-speed unwinding force can be advantageous from the viewpoint of reducing the labor required for unwinding and improving workability, and from the viewpoint of preventing the PSA sheet stretched during unwinding from shrinking after application to the adherend and causing lifting from the adherend. There is no particular lower limit for the high-speed unwinding force, but from the viewpoint of easily balancing with other properties, it is preferably, for example, 0.5 N / 20 mm or more, more preferably 1 N / 20 mm or more, and may be 1.5 N / 20 mm or more. From the viewpoint of preventing inconveniences such as excessive unwinding from the roll form, it is preferable that the high-speed unwinding force is not too small. The high-speed unwinding force can be measured in accordance with JIS Z0237:2009. The high-speed unwinding force can be adjusted, for example, by selecting the type of adhesive in the adhesive layer, the type and amount of crosslinking agent used, the type and treatment method of the release agent, or the use of optional components such as a tackifying resin.

[0138] <Application> The pressure-sensitive adhesive sheet disclosed herein has high high-speed peel strength, suppresses peeling noise when the surface of the pressure-sensitive adhesive layer is exposed prior to application to an adherend, and does not slip excessively even when placed on a metal plate or the like, making it suitable for use as, for example, a surface protection material (which may also be understood as a surface-protecting pressure-sensitive adhesive sheet). The pressure-sensitive adhesive sheet disclosed herein can be used for protecting the surfaces of components such as metal plates, painted plates, aluminum sashes, resin plates, decorative steel plates, vinyl chloride-laminated steel plates, glass plates, optical films for liquid crystals such as polarizing films, optical components such as liquid crystal panels, electronic components, etc., when transporting, processing, or curing these components.

[0139] The adhesive sheet disclosed herein can be preferably used as one form of surface protection in a state where it is attached to a workpiece to be processed by various lasers and laser cut in conjunction with the laser processing of the workpiece. The laser light used for the laser processing is not particularly limited, and various conventionally known lasers can be used. For example, excimer lasers such as ArF excimer laser, KrF excimer laser, and XeCl excimer laser, solid-state lasers such as YAG laser, YLF laser, YVO4 laser, and titanium sapphire laser, semiconductor lasers (sometimes called diode lasers), fiber lasers, carbon dioxide lasers, etc. can be used. The type of laser processing performed on the workpiece with the adhesive sheet disclosed herein attached is not particularly limited, and can be, for example, cutting, drilling, cutting, engraving, etc.

[0140] The material of the workpiece is not particularly limited as long as it can be cut by laser light (e.g., laser light from a carbon dioxide laser or fiber laser). Examples of the material include metal or semimetal materials such as iron, iron alloys (carbon steel, stainless steel, chromium steel, nickel steel, etc.), aluminum, aluminum alloys, nickel, tungsten, copper, copper alloys, titanium, titanium alloys, and silicon; resin materials such as polyolefin resin, polycarbonate resin, and acrylic resin; ceramic materials such as alumina, silica, sapphire, silicon nitride, tantalum nitride, titanium carbide, silicon carbide, gallium nitride, and gypsum; glass materials such as aluminosilicate glass, soda-lime glass, soda-aluminosilicate glass, and quartz glass; cellulose-based materials such as paper, cardboard, wood, and plywood; and laminates and composites thereof. Suitable examples of the workpiece include metal materials such as iron, aluminum, copper, titanium, and alloys containing these metals as the main component (e.g., stainless steel). The shape of the workpiece is not particularly limited and may be plate-shaped, cylindrical, block-shaped, or the like. The adhesive sheet disclosed herein is preferable because it prevents lateral sliding even when it is attached to a metal plate as a workpiece and placed on top of it.

[0141] The adhesive sheet disclosed herein can be preferably used in such laser processing by adhering it to the surface of the workpiece on the side irradiated with laser light. Furthermore, for the purpose of protecting the surface of the workpiece before, during, or after laser processing, the adhesive sheet can also be attached to the surface (back surface) of the workpiece opposite the side irradiated with laser light. The adhesive sheet disclosed herein can be preferably used in such laser processing using a short-wavelength laser with a dominant wavelength of 900 to 1100 nm. Examples of such short-wavelength lasers that can be used include fiber lasers with a dominant wavelength of approximately 1050 nm and diode lasers with a dominant wavelength of approximately 950 nm.

[0142] The matters disclosed by this specification include the following: (1) A pressure-sensitive adhesive sheet comprising a resin film as a substrate and a pressure-sensitive adhesive layer provided on a first surface of the substrate, the pressure-sensitive adhesive layer comprises a base polymer containing natural rubber, a tackifier, and an isocyanate-based crosslinking agent; The tackifier contains at least a tackifier A and a tackifier B, The Hansen solubility parameter distance Ra (NR-A) between the tackifier A and natural rubber is 1.5 or less, the content of the tackifier A is 40 parts by weight or more and less than 100 parts by weight relative to 100 parts by weight of the base polymer, The Hansen solubility parameter distance Ra (NR-B) between the tackifier B and natural rubber is 2.5 or more and 5.0 or less, the content of the tackifier B is 5 parts by weight or more and less than 35 parts by weight relative to 100 parts by weight of the base polymer, The pressure-sensitive adhesive sheet for laser processing, wherein the pressure-sensitive adhesive layer has a gel fraction of 15% or more and less than 60%. (2) The adhesive sheet for laser processing described in (1) above, wherein the difference between the Hansen solubility parameter distance Ra(NR-A) between the tackifier A and natural rubber and the Hansen solubility parameter distance Ra(NR-B) between the tackifier B and natural rubber is 1.8 or more (e.g., 2.0 or more). (3) The pressure-sensitive adhesive sheet for laser processing according to (1) or (2) above, wherein the tackifier A comprises at least one selected from aliphatic petroleum resins. (4) The pressure-sensitive adhesive sheet for laser processing according to any one of (1) to (3) above, wherein the tackifier B comprises at least one selected from the group consisting of rosin resins, rosin derivative resins, and terpene resins. (5) The pressure-sensitive adhesive sheet for laser processing according to any one of (1) to (4) above, wherein the substrate is a polyolefin resin film or a polyester resin film. (6) The pressure-sensitive adhesive sheet for laser processing according to any one of (1) to (5) above, wherein the substrate contains a laser beam absorbent. (7) The pressure-sensitive adhesive sheet for laser processing according to any one of (1) to (6) above, wherein the second surface of the substrate is made of a resin composition containing a release agent. (8) The pressure-sensitive adhesive sheet according to (7), wherein the release agent comprises a silicone-based release agent. (9) The pressure-sensitive adhesive sheet according to (8) above, wherein the silicone-based release agent contains a silylated polyolefin. (10) The pressure-sensitive adhesive sheet according to any one of (7) to (9) above, wherein the substrate and a resin composition containing the release agent are integrally formed by co-extrusion molding. (11) The pressure-sensitive adhesive sheet according to any one of (7) to (10), wherein the substrate comprises a back layer made of a resin composition containing the release agent, and a support layer disposed inside the back layer. (12) The pressure-sensitive adhesive sheet according to (11) above, wherein the support layer is a polyolefin resin layer or a polyester resin layer.

[0143] (13) The pressure-sensitive adhesive sheet according to any one of (1) to (12) above, wherein the substrate contains a laser beam absorbent. (14) The pressure-sensitive adhesive sheet according to (13) above, wherein the laser beam absorbent comprises at least one selected from the group consisting of carbon black, titanium oxide, iron-based oxides, titanium black, and manganese-based oxides. (15) The pressure-sensitive adhesive sheet according to any one of (1) to (14) above, which is used by being cut with a laser beam having a dominant wavelength of 900 nm to 1100 nm. (16) The pressure-sensitive adhesive sheet according to any one of (1) to (15) above, wherein the pressure-sensitive adhesive layer has a thickness of 15 μm or less.

[0144] (17) Preparing an object to be processed to which the pressure-sensitive adhesive sheet according to any one of (1) to (16) above is attached; and Irradiating the object to be processed with the adhesive sheet attached with laser light having a dominant wavelength of 900 nm to 1100 nm, thereby laser processing the object to be processed and cutting the adhesive sheet with the laser light; A method for manufacturing a laser-machined article, comprising: (18) The method according to (17), wherein the workpiece to be processed is irradiated with the laser light has the adhesive sheet attached to at least one of the surface of the workpiece to be processed that is irradiated with the laser light and the opposite surface. (19) further post-processing the object after the laser processing; and Peeling and removing the adhesive sheet from the object to be processed; The method according to (17) or (18) above, comprising the steps of: (20) The method according to any one of (17) to (19) above, wherein the object is a metal plate. (21) A roll comprising the pressure-sensitive adhesive sheet according to any one of (1) to (16) above, wound so that the pressure-sensitive adhesive layer is in contact with the second surface of the substrate. (22) The roll body according to (21) above, wherein the high-speed unwinding force is 1 N / 20 mm or more and 5 N / 20 mm or less. [Example]

[0145] Several examples of the present invention will be described below, but it is not intended that the present invention be limited to these specific examples. In the following description, "parts" and "%" are by weight unless otherwise specified. Furthermore, unless otherwise specified, the amount of each material used is based on the amount of active ingredient.

[0146] In the following examples, the tackifiers used to prepare the pressure-sensitive adhesive sheets are as follows: Tackifier A1: Aliphatic petroleum resin (manufactured by Zeon Corporation, product name "Quintone A100", HSP distance with natural rubber 0.8) Tackifier B1: Polymerized rosin (manufactured by Arakawa Chemical Industries, Ltd., product name "Aradigm R-95", HSP distance with natural rubber 2.9) Tackifier B2: Terpene phenol (manufactured by Arakawa Chemical Industries, Ltd., product name "YS Polystar T100", HSP distance with natural rubber 2.7) Tackifier B3: Xylene resin (manufactured by Fudow Co., Ltd., product name "Nikanol H-80", HSP distance with natural rubber 4.9) Tackifier B4: Rosin ester (manufactured by Arakawa Chemical Industries, Ltd., product name "Super Ester A100")

[0147] The HSP distance between the tackifier used to prepare the PSA sheets in each example and the natural rubber was calculated using structural formula editor software (Material Studio (ver. 8.0) and Open Babel GUI (ver. 2.4.1)) and HSPiP (5th Edition 5.2.06). The calculated HSP distance between each tackifier and the natural rubber is also listed in the "HSP Distance" column in Tables 1 and 2.

[0148] The HSP of tackifier B4 could not be calculated using HSPiP due to the complexity of its molecular structure. Given its structural similarity to other rosin-based resins, the HSP distance between tackifier B4 and natural rubber is estimated to be approximately 2 to 5. The "HSP distance" column in Tables 1 and 2 lists the estimated HSP distance between tackifier B4 and natural rubber.

[0149] <Preparation of adhesive sheet> (Example 1) The adhesive composition of Example 1 was prepared by adding and mixing 50 parts of tackifier A1, 25 parts of tackifier B1, 2 parts of an antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac NS-5"), 2.5 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), and toluene to 100 parts of natural rubber.

[0150] A support layer-forming material consisting of 3 parts black masterbatch (FeO masterbatch) containing 40% FeO (iron tetroxide powder with an average particle size of 250 nm) in polyolefin (hereinafter referred to as "FeO masterbatch") and 97 parts low-density polyethylene (LDPE, manufactured by Tosoh Corporation under the trade name "Petrothene 186R") was used. This back layer-forming material consisted of 94 parts of the support layer-forming material and 6 parts silylated polyolefin masterbatch containing approximately 30% silylated polyolefin (prepared as described in the examples of JP 2011-26448 A) and approximately 70% PE resin (1.8% silicone release agent). The back layer-forming material was co-extruded at a die temperature of 180°C using an inflation molding method to obtain a two-layer resin film consisting of a support layer and a back layer. The total thickness of this resin film was 80 μm, of which the back layer was 8 μm. The first surface (the surface other than the release surface) of the resin film was subjected to a corona discharge treatment, and the pressure-sensitive adhesive composition of Example 1 was applied to the corona discharge-treated surface and dried to form a pressure-sensitive adhesive layer having a thickness of 12 μm. In this way, a pressure-sensitive adhesive sheet was obtained having a pressure-sensitive adhesive layer on the first surface of the substrate and a second surface of the substrate serving as a release surface.

[0151] (Examples 2-7, 15, 16) Pressure-sensitive adhesive sheets of Examples 2 to 7, 15, and 16 were obtained in the same manner as Example 1, except that the amounts of tackifier A1, tackifier B1, and isocyanate crosslinking agent added per 100 parts of natural rubber were changed as shown in Table 1.

[0152] (Example 8) The adhesive composition of Example 8 was prepared by adding and mixing 50 parts of tackifier A1, 25 parts of tackifier B2, 2 parts of an antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac NS-5"), 2.5 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), and toluene to 100 parts of natural rubber. An adhesive sheet of Example 8 was obtained in the same manner as in Example 1, except that the adhesive composition of Example 8 was used instead of the adhesive composition of Example 1.

[0153] (Example 9) The adhesive composition of Example 9 was prepared by adding and mixing 50 parts of tackifier A1, 25 parts of tackifier B3, 2 parts of an antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac NS-5"), 2.5 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), and toluene to 100 parts of natural rubber. An adhesive sheet of Example 9 was obtained in the same manner as in Example 1, except that the adhesive composition of Example 9 was used instead of the adhesive composition of Example 1.

[0154] (Example 10) The adhesive composition of Example 10 was prepared by adding and mixing 90 parts of tackifier B1, 2 parts of an antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac NS-5"), 3.0 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), and toluene to 100 parts of natural rubber. An adhesive sheet of Example 10 was obtained in the same manner as in Example 1, except that the adhesive composition of Example 10 was used instead of the adhesive composition of Example 1.

[0155] (Example 11) To 100 parts of natural rubber, 70 parts of tackifier B2, 2 parts of an antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac NS-5"), 3.0 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), and toluene were added and mixed to prepare the adhesive composition of Example 11. An adhesive sheet of Example 11 was obtained in the same manner as in Example 1, except that the adhesive composition of Example 11 was used instead of the adhesive composition of Example 1.

[0156] (Example 12) To 100 parts of natural rubber, 90 parts of tackifier B4, 2 parts of an antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., product name "Nocrac NS-5"), 3.0 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, product name "Coronate L"), and toluene were added and mixed to prepare the adhesive composition of Example 12. An adhesive sheet of Example 12 was obtained in the same manner as in Example 1, except that the adhesive composition of Example 12 was used instead of the adhesive composition of Example 1.

[0157] (Example 13) To 100 parts of natural rubber, 70 parts of tackifier A1, 2 parts of an antioxidant (manufactured by Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocrac NS-5"), 3.0 parts of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, trade name "Coronate L"), and toluene were added and mixed to prepare the adhesive composition of Example 13. An adhesive sheet of Example 13 was obtained in the same manner as in Example 1, except that the adhesive composition of Example 13 was used instead of the adhesive composition of Example 1.

[0158] (Example 14) A pressure-sensitive adhesive sheet of Example 14 was obtained in the same manner as in Example 13, except that the amount of isocyanate-based crosslinking agent added per 100 parts of natural rubber was changed as shown in Table 2.

[0159] <Performance evaluation> A sample of an appropriate size was cut from the pressure-sensitive adhesive sheet prepared above, and the following items were evaluated. The results are shown in Table 1.

[0160] (1) High-speed peel strength (against polished plates) The surface of a stainless steel plate (SUS304) was buffed using a No. 400 buff and an abrasive called "Sizer 46" (manufactured by Koyosha Co., Ltd.). After polishing, metal powder and other particles generated by polishing were wiped off with a dry cloth to prepare a polished plate as the adherend. The pressure-sensitive adhesive sheet according to each example was cut into a strip measuring 10 mm wide and 100 mm long to prepare a test piece. The adhesive surface of the test piece was pressed against a polished plate as an adherend by rolling a 2 kg rubber roller as specified in JIS Z0237:2000 back and forth once. The sample was left for 30 minutes under a standard environment of 23°C and 50% RH, and then, under the standard environment, the high-speed peel strength (against the polished plate) (unit: N / 10 mm) was measured using a universal tensile tester (apparatus name "Tension and Compression Tester, TCM-1kNB" manufactured by Minebea Co., Ltd.) at a tensile speed of 30 m / min and a peel angle of 180°.

[0161] (2) Low-speed peel strength (against polished plate) As the adherend, a polished plate prepared in the same manner as used in the measurement of (1) high-speed peel strength (against polished plate) above was prepared. The pressure-sensitive adhesive sheet according to each example was cut into a strip measuring 10 mm wide and 100 mm long to prepare a test piece. The adhesive surface of the test piece was pressed against a polished plate as an adherend by rolling a 2 kg rubber roller as specified in JIS Z0237:2000 back and forth once. The sample was left for 30 minutes under a standard environment of 23°C and 50% RH, and then, under the standard environment, the low-speed peel strength (against the polished plate) (unit: N / 10 mm) was measured using a universal tensile tester (apparatus name "Tension and Compression Tester, TCM-1kNB" manufactured by Minebea Co., Ltd.) at a tensile speed of 0.3 m / min and a peel angle of 180°.

[0162] (3) Laser processability (vs. polished plates) The workpiece was a 3.0 mm thick SUS304 polished plate prepared in the same manner as in the measurement of high-speed peel strength (against polished plate) above (1), and the adhesive sheet according to each example was attached to the top surface of the workpiece. A cutting test was performed by irradiating a laser beam from the top side of this workpiece. Specifically, a fiber laser processing machine (Trumpf, Trulaser 5030, dominant wavelength 1050 nm) was used to perform straight cutting under the following conditions. [Laser processing conditions] Cutting speed: 5.0m / min Output: 3000W Supply gas and gas pressure: Nitrogen gas, pressure 18 bar Nozzle diameter: 2.0 mm Nozzle height: 2mm Laser beam focus: 1.5 mm below the top surface of the workpiece

[0163] The processed edge of the workpiece that had been laser processed (here, laser cut) was then visually inspected, and if the workpiece could be cut under the above conditions without any lifting or peeling of the adhesive sheet, the laser processability was evaluated as excellent (E); if lifting or peeling of the adhesive sheet was observed in an area of ​​approximately less than 10% of the processed edge of the workpiece, the laser processability was evaluated as good (G); and if lifting or peeling of the adhesive sheet was observed in an area of ​​approximately 10% or more of the processed edge of the workpiece, the laser processability was evaluated as poor (P).

[0164] (4) Bending workability (vs. polished plates) The adhesive sheet according to each example was attached to a 1.0 mm thick SUS304 polished plate prepared using the same method as used in the measurement of high-speed peel strength (against polished plate) above (1) using a laminator (linear pressure 40 N / cm, speed 3 m / min). The plate was left at room temperature for 30 minutes or more, and then bent 90° so that the adhesive sheet side was convex. The surface condition of the adherend after processing was then visually inspected, and the non-peeling property was rated as excellent (E) if no peeling of the adhesive sheet was observed from the surface of the adherend; good (G) if peeling of the adhesive sheet was observed over an area of ​​approximately less than 10%; and poor (P) if peeling of the adhesive sheet was observed over an area of ​​approximately 10% or more. After processing, the adhesive sheet was peeled off from the adherend at a pulling speed of approximately 0.3 m / min and a peel angle of approximately 180 degrees, and the surface condition of the adherend was visually inspected. If no adhesive residue was observed on the adherend surface, it was rated as good (G), and if adhesive residue was observed, it was rated as poor (P).

[0165] [Table 1]

[0166] [Table 2]

[0167] As shown in Tables 1 and 2, the pressure-sensitive adhesive sheets of Examples 1 to 9 had both excellent high-speed peel strength and excellent low-speed peel strength, and when a workpiece was processed with the pressure-sensitive adhesive sheet using a fiber laser, the adhesive sheet could be cut without lifting or peeling, and no peeling or adhesive residue occurred during subsequent bending. On the other hand, the pressure-sensitive adhesive sheets of Examples 10 to 12, which did not use tackifier A, tended to have lower low-speed peel strength than the pressure-sensitive adhesive sheets of Examples 1 to 9, and at least one of peeling and adhesive residue occurred during bending. Furthermore, the pressure-sensitive adhesive sheet of Example 12, which had a gel fraction of 11.5%, was observed to have adhesive residue.

[0168] The PSA sheet of Example 13, which did not use tackifier B, had both lower low-speed peel strength and high-speed peel strength than the PSA sheets of Examples 1 to 9, and adhesive residue was observed in the PSA sheet of Example 14, which had a gel fraction of 8.5% due to a reduced content of crosslinker. Furthermore, the PSA sheets of Examples 15 and 16, which used a combination of tackifier A and tackifier B but contained less tackifier A than the PSA sheets of Examples 1 to 9, tended to have inferior low-speed peel strength compared to the PSA sheets of Examples 1 to 9.

[0169] 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]

[0170] 1,2 Adhesive sheet 10 Resin film (base material) 10A front page 10B Second surface (back, peeling surface) 11 Back layer 12 Support layer 20 adhesive layer 20A surface (adhesive surface) 50 roll body 52 cores

Claims

1. A pressure-sensitive adhesive sheet comprising a resin film as a substrate and a pressure-sensitive adhesive layer provided on a first surface of the substrate, the pressure-sensitive adhesive layer comprises a base polymer containing natural rubber, a tackifier, and an isocyanate-based crosslinking agent; The tackifier includes at least a tackifier A and a tackifier B, The Hansen solubility parameter distance Ra (NR-A) between the tackifier A and the natural rubber is 1.5 or less, the content of the tackifier A is 40 parts by weight or more and less than 100 parts by weight relative to 100 parts by weight of the base polymer, The Hansen solubility parameter distance Ra(NR-B) between the tackifier B and the natural rubber is 2.5 or more and 5.0 or less, the content of the tackifier B is 5 parts by weight or more and less than 35 parts by weight relative to 100 parts by weight of the base polymer, The pressure-sensitive adhesive sheet for laser processing, wherein the pressure-sensitive adhesive layer has a gel fraction of 15% or more and less than 60%.

2. The pressure-sensitive adhesive sheet according to claim 1, wherein the difference between the Hansen solubility parameter distance Ra (NR-A) between the tackifier A and the natural rubber and the Hansen solubility parameter distance Ra (NR-B) between the tackifier B and the natural rubber is 1.8 or more.

3. The pressure-sensitive adhesive sheet according to claim 1 , wherein the tackifier A comprises at least one selected from aliphatic petroleum resins.

4. The pressure-sensitive adhesive sheet according to claim 1 , wherein the tackifier B comprises at least one selected from the group consisting of a rosin-based resin, a rosin derivative resin, and a terpene-based resin.

5. The pressure-sensitive adhesive sheet according to claim 1 , wherein the substrate is a polyolefin resin film or a polyester resin film.

6. The pressure-sensitive adhesive sheet according to claim 1 , wherein the substrate contains a laser beam absorbent.

7. The pressure-sensitive adhesive sheet according to claim 6 , wherein the laser beam absorbent comprises at least one selected from the group consisting of carbon black, titanium oxide, iron-based oxides, titanium black, and manganese-based oxides.

8. The pressure-sensitive adhesive sheet according to claim 1 , wherein the second surface of the substrate is made of a resin composition containing a release agent.

9. The pressure-sensitive adhesive sheet according to any one of claims 1 to 8, which is used by being cut with laser light having a dominant wavelength of 900 nm to 1100 nm.

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