Skin patch and electronic device

Abstract

A skin patch including a base material and an adhesive layer, wherein the adhesive layer includes a urethane-based adhesive, and is partially formed on at least one surface of the base material.

Description

Skin patches and electronic devices

[0001] The present invention relates to a skin patch and an electronic device, and in particular to a skin patch that can suppress adhesive residue and skin damage (amount of keratin peeling), and an electronic device equipped with the skin patch.

[0002] Wearable devices, which are electronic devices worn on the body of a user, have been known for a wide range of applications, including measuring a user's blood sugar level, electrocardiogram, electromyogram, body temperature, and the like.

[0003] Furthermore, there are various ways in which wearable devices can be attached. For example, devices that are attached by being attached to the user's body are known. Such devices are advantageous in that they adhere closely to the user's body, resulting in high accuracy of the information measured, and are easy to attach. For example, Patent Document 1 discloses a cardiac monitoring device that is attached to the skin. To attach such a device, an adhesive tape-like skin patch may be used.

[0004] International Publication No. 2020 / 158697

[0005] However, when a skin patch is applied to the skin, adhesive residue and skin damage (keratin peeling) may occur.

[0006] Furthermore, because the skin is flexible and stretches, the wearable device and the skin adhesive material may not be able to follow the expansion and contraction of the skin and may come off.

[0007] Therefore, there is a strong demand for the development of a skin patch that is less likely to peel off and that reduces adhesive residue and skin damage (amount of keratin peeled off).

[0008] In view of the above problems, the present invention aims to provide a skin patch that can suppress adhesive residue and skin damage (amount of keratin peeling), and an electronic device equipped with the skin patch.

[0009] The present inventors have conducted extensive research to solve the above-mentioned problems, and as a result have found that adhesive residue and skin damage (amount of keratin peeling) can be suppressed by devising the surface shape (adhesive layer shape) of a skin patch having a substrate and a urethane-based adhesive layer (for example, by partially forming a dotted, grid-like, wavy line, etc.), and have completed the present invention. That is, the present invention is as follows: [1] A skin patch having a substrate and an adhesive layer, the adhesive layer containing a urethane-based adhesive and partially formed on at least one surface of the substrate. [2] The skin patch according to [1] above, wherein the adhesive layer is formed in a dotted, grid-like, linear, or wavy line shape. [3] The skin patch according to [1] or [2] above, wherein the adhesive layer has an average content of ethylene oxide-based structural units of 60% by mass or less. [4] The skin patch according to any one of [1] to [3] above, wherein the urethane-based adhesive is a cured product of an adhesive composition containing a hydroxyl-terminated urethane prepolymer and a polyisocyanate compound. [5] The skin patch according to [4] above, wherein the adhesive composition has an average content of ethylene oxide-based structural units of 60% by mass or less. [6] The skin patch according to [4] or [5] above, wherein the hydroxyl-terminated urethane prepolymer is a reaction product of an oxyalkylene polymer and a diisocyanate compound in the presence of a tin-free catalyst. [7] The skin patch according to [6] above, wherein the tin-free catalyst contains at least one of zinc and bismuth. [8] The skin patch according to [6] or [7] above, wherein the oxyalkylene polymer has an average content of ethylene oxide-based structural units of 60% by mass or less. [9] The skin patch according to any one of [6] to [8] above, wherein the oxyalkylene polymer has an average number of hydroxyl groups per molecule of 1.5 to 3.0.

[10] The skin patch according to any one of [6] to [9] above, wherein the oxyalkylene polymer comprises an oxyalkylene polymer A having an average number of hydroxyl groups per molecule of 2.0 or more, and an oxyalkylene polymer B having one hydroxyl group per molecule.

[11] The skin patch according to

[10] above, wherein the oxyalkylene polymer A comprises an oxyalkylene polymer A1 having 3 hydroxyl groups per molecule and an oxyalkylene polymer A2 having 2 hydroxyl groups per molecule.

[12] An electronic device comprising the skin patch according to any one of [1] to

[11] above.

[0010] According to the present invention, it is possible to provide a skin patch that can suppress adhesive residue and skin damage (amount of keratin peeling), and an electronic device that includes the skin patch.

[0011] Fig. 1 is a schematic side view showing an example of a skin patch according to an embodiment of the present invention. Fig. 2 is a schematic view showing an example of a state in which a wearable device is attached to skin via a skin patch having adhesive surfaces on both sides. Fig. 3 is a schematic view showing an example of a state in which a wearable device is attached to skin via a skin patch having adhesive surfaces on only one side. Fig. 4 is a plan view showing an example of the shape (grid shape) of the adhesive layer of a skin patch according to an embodiment of the present invention. Fig. 5 is a plan view showing an example of the shape (linear shape) of the adhesive layer of a skin patch according to an embodiment of the present invention. Fig. 6 is a plan view showing an example of the shape (dot shape) of the adhesive layer of a skin patch according to an embodiment of the present invention. Fig. 7 is a plan view showing an example of the shape (wavy line shape) of the adhesive layer of a skin patch according to an embodiment of the present invention.

[0012] The present invention is described in detail below. However, the present invention is not limited to the embodiments described below. In this specification, preferred definitions can be adopted arbitrarily, and combinations of preferred definitions are considered more preferable. In this specification, the term "XX to YY" means "XX or more and YY or less." In this specification, the lower and upper limits of preferred numerical ranges (e.g., ranges of content, etc.) described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to obtain "10 to 60." Furthermore, in the numerical ranges described in this specification, the upper or lower limit of the numerical range may be replaced with a value shown in the examples. In this specification, "human skin" may also be simply referred to as "skin." The number average molecular weight (Mn) and weight average molecular weight (Mw) are polystyrene-equivalent molecular weights determined by gel permeation chromatography (GPC) based on a calibration curve prepared using standard polystyrene samples. The isocyanate index is the equivalent ratio ([isocyanate group] / [active hydrogen-containing group]) between the isocyanate group to be reacted and the active hydrogen-containing group (e.g., hydroxyl group), and is expressed as a percentage. For example, an isocyanate index of 85 indicates that the equivalent ratio between the isocyanate group and the active hydrogen-containing group (e.g., hydroxyl group) is 85%. In this specification, the term "solid content" refers to the non-volatile content excluding volatile substances such as solvents, and refers to the components that remain without volatilization when the pressure-sensitive adhesive composition is dried, including those that are liquid, syrup-like, or waxy at room temperature. The total solid content can also be calculated from the charge amount.

[0013] [Skin patch] The skin patch in an embodiment of the present invention (hereinafter sometimes simply referred to as "this embodiment") has a substrate and an adhesive layer partially formed on at least one side of the substrate, and may further have other layers as necessary.

[0014] FIG. 1 is a schematic side view showing an example of a skin patch according to the present embodiment. In FIG. 1, the skin patch 10 has a substrate (support) 20 and an adhesive layer 30. The adhesive layer 30 is partially formed on one side of the substrate 20. The side of the substrate 20 on which the partially formed adhesive layer 30 is formed may be referred to as the "first side," and the side opposite the first side may be referred to as the "second side." The skin patch 10 is attached to the skin via this adhesive layer 30. That is, the skin patch 10 has a portion on the skin-facing side (first side) where the adhesive layer 30 is not formed. The skin patch 10 reduces adhesive residue and skin damage (amount of keratin peeling).

[0015] The skin patch of this embodiment may have an adhesive surface on only one side or on both sides. That is, the skin patch of this embodiment may have only an adhesive layer partially formed on the first side of the substrate (hereinafter also referred to as the "first adhesive layer"), or may further have another adhesive layer formed on the second side (hereinafter also referred to as the "second adhesive layer"). The second adhesive layer may be partially formed on the second side of the substrate, or may be formed over the entire second side of the substrate.

[0016] 2 is a schematic diagram showing an example of a state in which a wearable device is attached to skin via a skin adhesive material having adhesive surfaces on both sides. In FIG. 2, a wearable device 160 is attached to skin 150 via a skin adhesive material 110 having a first adhesive layer 130 partially formed on a first surface of a substrate 120 and a second adhesive layer 140 formed on a second surface, i.e., a skin adhesive material 110 having adhesive surfaces on both sides. When attaching the wearable device 160 to skin via a skin adhesive material 110 having adhesive surfaces on both sides, for example, the partially formed first adhesive layer 130 is attached to the skin 150, and the second adhesive layer 140 is attached to the wearable device 160. As described below, a skin adhesive material 110 having adhesive surfaces on both sides is particularly resistant to peeling, and allows the wearable device 160 to be attached to the skin 150 with reduced adhesive residue and skin damage (amount of keratin peeling).

[0017] Furthermore, since the wearable device 160 is typically hard, it cannot expand and contract in accordance with the expansion and contraction of the skin, making it difficult to prevent peeling caused by the difference in elasticity between the skin 150 and the wearable device 160. On the other hand, as shown in Figure 2, when the wearable device 160 is attached to the skin 150 via the skin adhesive material 110, the base material 120 is present between the skin 150 and the wearable device 160. Therefore, if the base material 120 has excellent cushioning properties, it is possible to alleviate stress caused by the difference in elasticity between the skin 150 and the wearable device 160, and it is possible to prevent peeling caused by the difference in elasticity between the skin 150 and the wearable device 160.

[0018] Furthermore, when a wearable device is attached to the skin by covering it with a conventional skin adhesive, the wearable device is pressed against the skin and comes into direct contact with it, which can cause adhesive residue and skin damage (keratin peeling). On the other hand, when a wearable device 160 is attached to skin 150 via a skin adhesive 110 as shown in Figure 2, the wearable device 160 comes into contact with the skin 150 via the base material 120 and is not pressed against the skin 150, which can reduce the likelihood of adhesive residue and skin damage (keratin peeling).

[0019] 3 is a schematic diagram showing an example of a state in which a wearable device is attached to skin via a skin adhesive material having an adhesive surface on only one side. In FIG. 3, when wearing a wearable device 260 via a skin adhesive material 210 having an adhesive surface on only one side, i.e., a skin adhesive material 210 that does not have a second adhesive layer, it is preferable to attach the first adhesive layer 230 to the skin 250 and attach the wearable device 260 to the second surface of the base material 220 via an adhesive, double-sided adhesive tape, or the like (not shown). By attaching the wearable device 260 in this manner, it is possible to achieve the same effect as when using a skin adhesive material 110 having adhesive surfaces on both sides as shown in FIG. 2.

[0020] Although a preferred embodiment of wearing a wearable device using the skin adhesive material of this embodiment has been described, the use of the skin adhesive material of this embodiment is not limited to this. For example, the skin adhesive material of this embodiment may be attached to the skin so as to cover the wearable device, or the skin adhesive material of this embodiment may be used to protect a wound like a bandage, or may be used like surgical tape to secure a bandage, gauze, or the like to an affected area.

[0021] (Substrate) The thickness of the substrate is not particularly limited, but is preferably 100 to 3000 μm, more preferably 300 to 2000 μm, and particularly preferably 500 to 1500 μm. If the thickness of the substrate is equal to or greater than the lower limit, the cushioning properties of the substrate can be improved, while if the thickness is equal to or less than the upper limit, the substrate can be prevented from becoming easily cracked or slipping. The thickness of the substrate can be measured by the method described in the examples.

[0022] The density of the substrate is not particularly limited, but is preferably 0.05 to 0.50 g / cm ３ and more preferably 0.08 to 0.40 g / cm ３ , particularly preferably 0.10 to 0.35 g / cm ３ When the density of the substrate is equal to or greater than the lower limit, the strength of the skin patch can be ensured, while when the density is equal to or less than the upper limit, the stretchability and cushioning properties of the substrate can be improved. The density of the substrate can be measured by the method described in the Examples.

[0023] The cellular content of the substrate is not particularly limited, but is preferably 70.0 to 98.5%, more preferably 80.0 to 97.5%, and particularly preferably 85.0 to 97.5%. If the cellular content of the substrate is equal to or greater than the lower limit, the stretchability, cushioning properties, and moisture permeability of the skin patch can be improved, while if it is equal to or less than the upper limit, the strength of the skin patch can be ensured. The cellular content of the substrate can be measured by the method described in the Examples.

[0024] The stretchability of the substrate can be evaluated by various methods, for example, by the breaking strength and breaking elongation measured by the method described in the Examples. The breaking strength of the substrate is not particularly limited, but from the viewpoint of improving stretchability, it is preferably 20 N / 20 mm or less, more preferably 10 N / 20 mm or less, and particularly preferably 5 N / 20 mm or less. The breaking elongation of the substrate is not particularly limited, but from the viewpoint of improving stretchability, it is preferably 100% or more, more preferably 200% or more, and particularly preferably 250% or more.

[0025] The material of the substrate is not particularly limited, and examples thereof include amorphous crosslinked types such as polyurethane, polyolefin (polyethylene, polypropylene, copolymers thereof, etc.), silicone, acrylic, and rubber. These may be used alone or in combination of two or more. Among these, synthetic rubber (SBR) and polyurethane are preferred.

[0026] The method for producing the substrate is not particularly limited, and the substrate can be produced by, for example, any known method.

[0027] The substrate may or may not include an auxiliary layer. Examples of the auxiliary layer are not particularly limited, and include a colored layer, an undercoat layer, an antistatic layer, and the like provided on the surface of the substrate.

[0028] The surface of the substrate may be subjected to a surface treatment such as a physical treatment such as corona discharge treatment, plasma treatment, sand matting treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, or ionizing radiation treatment; a chemical treatment such as chromic acid treatment; or an easy-adhesion treatment using a coating agent (primer), for the purpose of improving adhesion and retention with the pressure-sensitive adhesive layer. The surface treatment for improving adhesion is preferably applied to the entire surface of the substrate layer.

[0029] (Adhesive Layer) The adhesive layer is not particularly limited as long as it contains a urethane-based adhesive, and may further contain, for example, an acrylic-based adhesive, a silicone-based adhesive, a rubber-based adhesive (natural rubber-based, synthetic rubber-based, a mixture thereof, etc.), a polyester-based adhesive, a polyether-based adhesive, a polyamide-based adhesive, a fluorine-based adhesive, etc. The content of the urethane-based adhesive in the adhesive layer is not particularly limited, but is preferably 60% by mass or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

[0030] The content of ethylene oxide-based structural units (hereinafter abbreviated as "EO units") in the pressure-sensitive adhesive layer is not particularly limited, but from the viewpoint of obtaining a pressure-sensitive adhesive that is gentle on the skin and has a good balance between adhesive strength to the skin and adhesive strength to a device, it is preferably 60% by mass or less, more preferably 8 to 55% by mass, even more preferably 10 to 50% by mass, still more preferably 12 to 40% by mass, and particularly preferably 15 to 25% by mass. The EO unit content in the pressure-sensitive adhesive layer is derived from the EO units that constitute the oxyalkylene chain of the oxyalkylene polymer in the hydroxyl-terminated urethane prepolymer, and １３ It can be determined by analyzing the monomer composition of the oxyalkylene chain in the pressure-sensitive adhesive layer by C-NMR (nuclear magnetic resonance) measurement.

[0031] The surface of the adhesive layer of the skin patch is preferably covered with a release liner to protect the surface of the adhesive layer before use. The release liner is appropriately peeled off from the surface of the adhesive layer when the skin patch is used. Release liners used in known adhesive tapes for skin can be used. Examples of release liners include fine paper or glassine paper coated with a release agent such as silicone resin or fluororesin; parchment paper; fine paper anchor coated with resin or laminated with polyethylene coated with a release agent such as silicone resin or fluororesin; and transparent resin films such as polyester films. The thickness of the release liner is not particularly limited, but is preferably 5 to 200 μm, more preferably 10 to 100 μm, and particularly preferably 20 to 50 μm, from the viewpoints of protecting the adhesive layer and facilitating peeling during use.

[0032] In this embodiment, the pressure-sensitive adhesive layer may be partially formed on at least one surface of the substrate, and its shape is not particularly limited, but may have a predetermined pattern such as a grid, line (straight line, wavy line, etc.), or dot (dot or island). Figures 4 to 7 are plan views showing examples of the shape of the pressure-sensitive adhesive layer of the skin patch of this embodiment. In Figures 4 to 7, the pressure-sensitive adhesive layer 30 may be formed on the substrate 20 in a grid pattern (Figure 4), line (Figure 5), dot (Figure 6), or wavy line (Figure 7).

[0033] Among these configurations, a wavy line configuration is particularly preferred because, when the skin patch of this embodiment is cut and used, the cross-sectional area of ​​the pattern shape changes little over time with application time, and the proportion of the area occupied by the adhesive layer on the cut surface is unlikely to change even when the cutting location and direction are different. If the proportion of the area occupied by the adhesive layer on the cut surface is unlikely to change, the adhesive strength near the cut portion (the edge of the skin patch) is unlikely to change, and peeling from the edge can be stably suppressed. In other words, by forming the adhesive layer into a wavy line shape, peeling from the edge can be stably suppressed regardless of the cutting location and direction of the skin patch of this embodiment. The wavy line shape may be a wavy line shape formed symmetrically on both sides of a baseline, such as a sine curve, pseudo-sine curve, triangular wave, or circular arc wave, or may be a wavy line progressing in an arc, triangle, ellipse, or other shape on only one side of the baseline. The line width, spacing (pitch), amplitude, period, etc. of the pattern shape can be appropriately set depending on the intended use. The above are merely examples, and the configuration of the pressure-sensitive adhesive layer is not limited to these.

[0034] The adhesive strength of the adhesive layer in the skin patch to human skin is not particularly limited, but is preferably 0.5 to 4.0 N / 15 mm, more preferably 1.0 to 3.5 N / 15 mm, even more preferably 1.5 to 3.0 N / 15 mm, and particularly preferably 2.0 to 2.5 N / 15 mm. When the adhesive strength of the adhesive layer to human skin is equal to or greater than the lower limit, the skin patch will adhere well to the skin. When the adhesive strength of the adhesive layer to human skin is equal to or less than the upper limit, the condition of the skin after peeling the skin patch from the skin will be good, and the skin patch will be gentler on the skin. Note that the "adhesive strength to human skin" here is measured using the same method as in the Examples.

[0035] The amount of keratin peeled off after the adhesive layer of the skin patch is attached to human skin for one day ("amount of keratin peeled off after one day of attachment") is not particularly limited, but is preferably 0.050 mg / cm ２ or less, more preferably 0.040 mg / cm ２ More preferably, 0.030 mg / cm or less２ More preferably, 0.020 mg / cm or less ２ Particularly preferably 0.015 mg / cm ２ When the amount of keratin peeled after one day of application is equal to or less than the upper limit, the condition of the skin after the skin patch is peeled off from the skin is good, and the skin-friendly property is excellent. Note that the "amount of keratin peeled after one day of application" here is measured in the same manner as in the Examples.

[0036] The adhesive strength of the adhesive layer in the skin patch to a phenolic substrate is not particularly limited, but is preferably 1.0 to 8.0 N / 15 mm, more preferably 1.2 to 7.5 N / 15 mm, and particularly preferably 1.5 to 7.0 N / 15 mm. When the adhesive strength of the adhesive layer to a phenolic substrate is equal to or greater than the lower limit, the skin patch adheres well to the phenolic substrate, resulting in excellent fixation of the wearable device. On the other hand, when the adhesive strength of the adhesive layer to a phenolic substrate is equal to or less than the upper limit, the skin patch can be easily peeled off when using the wearable device repeatedly, resulting in excellent convenience. Note that the "adhesive strength to a phenolic substrate" here is measured using the same method as in the Examples.

[0037] The thickness of the skin patch is not particularly limited, but is preferably 200 to 3100 μm, more preferably 600 to 2100 μm, and particularly preferably 1000 to 1600 μm. If the thickness of the skin patch is within the above range, it can be worn for a long period of time. The "thickness of the skin patch" here is measured in the same manner as the "thickness of the base material".

[0038] The adhesive layer may be a single layer or multiple layers. The adhesive layers provided on the skin patch may be the same adhesive layer, or may be adhesive layers with different compositions, thicknesses, physical properties, etc.

[0039] The thickness of the pressure-sensitive adhesive layer is not particularly limited, but from the viewpoint of ensuring good adhesion to the skin, it is preferably 5 to 200 μm, more preferably 10 to 150 μm, and particularly preferably 15 to 150 μm. Here, the "thickness of the pressure-sensitive adhesive layer" is measured in the same manner as the "thickness of the substrate." For example, in the case of a lattice-shaped pressure-sensitive adhesive layer, the thickness of the pressure-sensitive adhesive layer means the thickness of the pressure-sensitive adhesive layer at the shortest distance from the part of the pressure-sensitive adhesive that contacts the substrate to the part that contacts the skin.

[0040] From the viewpoint of suppressing adhesive residue and skin damage (amount of keratin peeling), the urethane-based adhesive is preferably a cured product of an adhesive composition containing a hydroxyl-terminated urethane prepolymer and a polyisocyanate compound. The urethane-based adhesive obtained by curing such an adhesive composition has good adhesive strength of the adhesive layer to the skin, is less likely to leave adhesive residue, and can be suitably applied to the skin.

[0041] <Adhesive Composition> The adhesive composition contains, for example, a hydroxyl group-terminated urethane prepolymer and a polyisocyanate compound, and optionally contains a tackifier resin and other components.

[0042] The content of ethylene oxide-based structural units (hereinafter abbreviated as "EO units") in the pressure-sensitive adhesive composition is not particularly limited, but from the viewpoint of obtaining a pressure-sensitive adhesive that is gentle on the skin and has a good balance between adhesive strength to the skin and adhesive strength to a device, it is preferably 60% by mass or less, more preferably 8 to 55% by mass, even more preferably 10 to 50% by mass, still more preferably 12 to 40% by mass, and particularly preferably 15 to 25% by mass. The EO unit content in the pressure-sensitive adhesive composition is derived from the EO units that constitute the oxyalkylene chain of the oxyalkylene polymer in the hydroxyl-terminated urethane prepolymer, and １３ It can be determined by analyzing the monomer composition of the oxyalkylene chain in the pressure-sensitive adhesive composition by C-NMR (nuclear magnetic resonance) measurement.

[0043] <<Hydroxyl-Terminated Urethane Prepolymer>> The hydroxyl-terminated urethane prepolymer is a reaction product of an oxyalkylene polymer and a diisocyanate compound. The hydroxyl-terminated urethane prepolymer is preferably a reaction product obtained by reacting an oxyalkylene polymer with a diisocyanate compound in the presence of a tin-free catalyst.

[0044] The EO unit content in the hydroxyl-terminated urethane prepolymer is not particularly limited, but is preferably 60% by mass or less, more preferably 5 to 55% by mass, even more preferably 10 to 50% by mass, even more preferably 12 to 40% by mass, and particularly preferably 15 to 25% by mass. By having the EO unit content in the hydroxyl-terminated urethane prepolymer within the above range, it is easy to obtain a PSA that is gentle on the skin and has a good balance of adhesion to the skin and adhesion to a device. The EO unit content in the hydroxyl-terminated urethane prepolymer was determined as a weighted average of the EO unit content in each component of the raw materials. Note that, like the EO unit content in the PSA composition, the EO unit content in the hydroxyl-terminated urethane prepolymer is also determined as follows: １３ It can also be determined by C-NMR measurement.

[0045] -Oxyalkylene Polymer- The average content of EO units in the oxyalkylene polymer is not particularly limited, but is preferably 60% by mass or less, more preferably 8 to 55% by mass, even more preferably 10 to 50% by mass, even more preferably 12 to 40% by mass, and particularly preferably 15 to 25% by mass. When multiple oxyalkylene polymers are used in the synthesis of the hydroxyl group-terminated urethane prepolymer, the average content of EO units in the oxyalkylene polymer refers to the weighted average value of the EO unit contents in each oxyalkylene polymer based on the blend amounts of these multiple oxyalkylene polymers. The EO unit content in each oxyalkylene polymer is a value calculated based on the EO blend amount of the raw material in the synthesis of the oxyalkylene polymer. Note that, like the EO unit content in the pressure-sensitive adhesive composition, the EO unit content in the oxyalkylene polymer also refers to the weighted average value of the EO unit contents in each oxyalkylene polymer based on the blend amount of these multiple oxyalkylene polymers. １３When the average content of EO units in the oxyalkylene polymer is within the above range, it is easy to obtain a pressure-sensitive adhesive that is gentle on the skin and has a good balance between adhesive strength to the skin and adhesive strength to a device.

[0046] The average number of hydroxyl groups per molecule of the oxyalkylene polymer is not particularly limited, but from the viewpoint of obtaining a pressure-sensitive adhesive that is gentle on the skin and has a good balance of adhesion to the skin and adhesion to a device, it is preferably 1.5 to 3.0, more preferably 1.7 to 2.8, and particularly preferably 1.9 to 2.6. The average number of hydroxyl groups per molecule of the oxyalkylene polymer refers to the weighted average value of the number of hydroxyl groups per molecule of the oxyalkylene polymer based on the blend amounts of multiple oxyalkylene polymers used in the synthesis of the hydroxyl-terminated urethane prepolymer. The oxyalkylene polymer may be one type of oxyalkylene polymer, or two or more types of oxyalkylene polymers.

[0047] The oxyalkylene polymer preferably includes an oxyalkylene polymer A (hereinafter sometimes simply referred to as "polymer A") having two or more hydroxyl groups per molecule, and an oxyalkylene polymer B (hereinafter sometimes simply referred to as "polymer B") having one hydroxyl group per molecule. The hydroxyl groups of polymer A and polymer B react with the isocyanate group of the diisocyanate compound to form a urethane bond, thereby producing a hydroxyl-terminated urethane prepolymer. It is preferable that the unreacted hydroxyl groups in the hydroxyl groups of polymer A and polymer B are terminal hydroxyl groups of the molecular chain of the hydroxyl-terminated urethane prepolymer.

[0048] The total content of polymer A and polymer B in the oxyalkylene polymer is not particularly limited, but is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, and particularly preferably 100% by mass. The content ratio of polymer A to polymer B in the oxyalkylene polymer is not particularly limited, but from the viewpoint of obtaining a pressure-sensitive adhesive having a good balance between adhesive strength to skin and adhesive strength to a device, the mass ratio is preferably 10 / 90 to 95 / 5, more preferably 30 / 70 to 90 / 10, even more preferably 50 / 50 to 85 / 15, and particularly preferably 60 / 40 to 85 / 15.

[0049] --Oxyalkylene Polymer A-- Polymer A has two or more hydroxyl groups per molecule, preferably two to six. Polymer A may be one type of oxyalkylene polymer, or two or more types of oxyalkylene polymers. When polymer A is composed of two or more types of oxyalkylene polymers, the adhesive strength of the adhesive can be easily adjusted. When polymer A is composed of two or more types of oxyalkylene polymers, the average number of hydroxyl groups per molecule of polymer A is not particularly limited, but is preferably 2.1 to 3.0, more preferably 2.2 to 2.9, and particularly preferably 2.3 to 2.8. When the average number of hydroxyl groups of polymer A is within the above range, stress on the skin to which the device is fixed is reduced, and an adhesive that is less likely to leave adhesive residue on the skin can be obtained. The average number of hydroxyl groups per molecule of polymer A can be calculated from the measured hydroxyl value and Mn of polymer A using the formula: hydroxyl value × Mn / 56100. The hydroxyl value can be measured by the method described in the Examples.

[0050] When polymer A is composed of two or more oxyalkylene polymers, examples of polymer A include an oxyalkylene polymer A1 having three hydroxyl groups per molecule (hereinafter sometimes simply referred to as "polymer A1") and an oxyalkylene polymer A2 having two hydroxyl groups per molecule (hereinafter sometimes simply referred to as "polymer A2"). Polymer A1 may be a single type or two or more types. Similarly, polymer A2 may be a single type or two or more types. Polymer A may contain an oxyalkylene polymer having four or more hydroxyl groups per molecule. When polymer A is composed of polymer A1 and polymer A2, the weighted average value based on the composition ratio (blending amount) of polymer A1 and polymer A2, where polymer A1 has three hydroxyl groups per molecule and polymer A2 has two hydroxyl groups per molecule, can be considered to be the average number of hydroxyl groups of polymer A.

[0051] The total amount of polymer A1 and polymer A2 in 100 parts by mass of polymer A is not particularly limited, but is preferably 85 parts by mass or more, more preferably 90 parts by mass or more, and particularly preferably 95 parts by mass or more, from the viewpoint of ease of adjusting the adhesive strength of the pressure-sensitive adhesive, etc. It is particularly preferred that the total amount of polymer A1 and polymer A2 in 100 parts by mass of polymer A is 100 parts by mass, i.e., polymer A consists of polymer A1 and polymer A2.

[0052] The content of polymer A1 is not particularly limited, but from the viewpoint of good adhesive strength of the pressure-sensitive adhesive and suppression of adhesive residue, it is preferably 20 parts by mass or more, more preferably 25 to 95 parts by mass, and particularly preferably 30 to 90 parts by mass, per 100 parts by mass of the total of polymer A1 and polymer A2. The content of polymer A2 is not particularly limited, but from the same viewpoint, it is preferably 80 parts by mass or less, more preferably 5 to 75 parts by mass, and particularly preferably 10 to 70 parts by mass, per 100 parts by mass of the total of polymer A1 and polymer A2.

[0053] For example, when polymer A consists of polymer A1 and polymer A2, the content of polymer A1 is not particularly limited, but from the viewpoint of obtaining a pressure-sensitive adhesive having a good balance between adhesive strength to skin and adhesive strength to a device, it is preferably 10 to 45 parts by mass, more preferably 15 to 40 parts by mass, and particularly preferably 30 to 40 parts by mass, per 100 parts by mass of the total of polymer A1, polymer A2, and polymer B in the oxyalkylene polymer. The content of polymer A2 is not particularly limited, but from the same viewpoint, it is preferably 15 to 50 parts by mass, more preferably 30 to 50 parts by mass, and particularly preferably 40 to 50 parts by mass, per 100 parts by mass of the total of polymer A1, polymer A2, and polymer B in the oxyalkylene polymer. The content ratios of polymer A1, polymer A2, and polymer B are preferably polymer A2, polymer A1, and polymer B, in descending order.

[0054] The average content of EO units in polymer A is not particularly limited, but is preferably 0 to 80% by mass, more preferably 0 to 70% by mass, even more preferably 0 to 60% by mass, and particularly preferably 0 to 50% by mass. １３ The monomer composition of the oxyalkylene chain in polymer A can be analyzed and determined by C-NMR measurement. For example, when the oxyalkylene chain in polymer A is composed of EO units and units based on propylene oxide (also referred to as "PO units"), the EO unit content can be calculated based on the area of ​​the peak representing the methylene group of the EO unit and the area of ​​the peak representing the methyl group of the PO unit. When polymer A is composed of, for example, polymer A1 and polymer A2, the EO unit contents of polymer A1 and polymer A2 are similar. The average EO unit content in polymer A can be considered to be a value calculated from the amount of EO blended in the raw materials for synthesizing polymer A. When polymer A is composed of, for example, polymer A1 and polymer A2, the EO unit content of polymer A can be considered to be the weighted average of the EO unit content of polymer A1 and the EO unit content of polymer A2 based on the compositional proportions (blending amounts) of polymer A1 and polymer A2.

[0055] The Mn of polymer A is not particularly limited, but from the viewpoints of achieving good adhesive strength of the PSA, suppressing adhesive residue, and forming a PSA layer with good flexibility, it is preferably 1,000 to 50,000, more preferably 5,000 to 30,000, and particularly preferably 8,000 to 25,000. The Mw / Mn (molecular weight distribution) of polymer A is not particularly limited, but from the viewpoints of being close to 1 and having a narrow molecular weight distribution, the hydroxyl-terminated urethane prepolymer is less likely to become highly viscous and the synthesis is more efficient, it is preferably 1.25 or less, more preferably 1.22 or less, and particularly preferably 1.20 or less. The unsaturation degree of polymer A is also not particularly limited, but from the viewpoints of achieving good curing properties of the hydroxyl-terminated urethane prepolymer and suppressing adhesive residue of the PSA, it is preferable that it is closer to 0 meq / g, preferably 0.020 meq / g or less, more preferably 0.018 meq / g or less, and particularly preferably 0.015 meq / g or less. When polymer A is composed of two or more kinds of oxyalkylene polymers, it is preferable that each of the oxyalkylene polymers has Mn, Mw / Mn and degree of unsaturation within the above ranges.

[0056] The synthesis method of polymer A is not particularly limited, and for example, it can be obtained by ring-opening addition polymerization of a compound having a cyclic ether structure, preferably an alkylene oxide, with an initiator having two or more active hydrogens in the presence of a catalyst. When polymer A consists of polymer A1 and polymer A2, a method can also be used in which an initiator having three active hydrogens and an initiator having two active hydrogens are used in combination to perform ring-opening addition polymerization of a compound having a cyclic ether structure, thereby simultaneously producing polymer A1 and polymer A2. From the viewpoint of more accurately adjusting the blending amounts of polymer A1 and polymer A2, a method is preferred in which polymer A1 obtained by ring-opening addition polymerization of a compound having a cyclic ether structure with an initiator having three active hydrogens and polymer A2 obtained by ring-opening addition polymerization of a compound having a cyclic ether structure with an initiator having two active hydrogens are separately synthesized and then mixed.

[0057] The compound having a cyclic ether structure may be linear or branched. The number of carbon atoms in the compound having a cyclic ether structure is not particularly limited, but is preferably 2 to 14, more preferably 2 to 10, and particularly preferably 2 to 4. The compound having a cyclic ether structure is not particularly limited, and examples thereof include ethylene oxide (EO), propylene oxide (PO), 1,2-butylene oxide, 2,3-butylene oxide, methyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, lauryl glycidyl ether, hexyl glycidyl ether, and tetrahydrofuran. These may be used alone or in combination of two or more. Among these, EO and PO are preferred.

[0058] When two or more compounds having a cyclic ether structure are used in combination, the arrangement of the oxyalkylene groups derived from each compound in the polymer A may be random or block.

[0059] Examples of groups having active hydrogen in the initiator include hydroxyl groups, carboxyl groups, and amino groups having a hydrogen atom bonded to a nitrogen atom. These may be used alone, or two or more may be used in combination. Among these, hydroxyl groups are preferred, and alcoholic hydroxyl groups are more preferred. Examples of initiators having three hydroxyl groups include glycerin, trimethylolethane, trimethylolpropane, and 1,2,6-hexanetriol. These may be used alone, or two or more may be used in combination. Examples of initiators having two hydroxyl groups include ethylene glycol, diethylene glycol, propylene glycol, and dipropylene glycol. These may be used alone, or two or more may be used in combination.

[0060] The number of active hydrogens in the initiator usually corresponds to the number of hydroxyl groups per molecule of the oxyalkylene polymer. Polymer A1 can be synthesized, for example, using glycerin as an initiator. Polymer A2 can be synthesized, for example, using propylene glycol as an initiator. The initiators used as raw materials for synthesizing the oxyalkylene polymer are: １３When polymer A is composed of polymer A1 and polymer A2, the type and amount of polymer A can be identified by C-NMR measurement. １３ The ratio of polymer A1 to polymer A2 is determined by determining the content of oxyalkylene groups such as EO units and PO units bound to each initiator from information on the type and amount of the initiator obtained by C-NMR measurement.

[0061] Ring-opening addition polymerization can be carried out using known catalysts, such as alkali catalysts such as potassium hydroxide, transition metal compound-porphyrin complex catalysts such as complexes obtained by reacting an organoaluminum compound with porphyrin, composite metal cyanide complex catalysts, and catalysts made of phosphazene compounds. Among these catalysts, composite metal cyanide complex (DMC) catalysts are preferred because they tend to produce oxyalkylene polymers with narrow molecular weight distributions and relatively low viscosity. Known compounds can be used as composite metal cyanide complexes, such as zinc hexacyanocobaltate complexes with tert-butanol as a ligand. Synthesis of oxyalkylene polymers by ring-opening addition polymerization using a DMC catalyst can be carried out by known methods, for example, production methods described in WO 2003 / 062301, WO 2004 / 067633, JP 2004-269776 A, JP 2005-15786 A, WO 2013 / 065802, JP 2015-10162 A, etc. can be applied.

[0062] --Oxyalkylene Polymer B-- The oxyalkylene polymer B has one hydroxyl group per molecule. As the polymer B, one type of oxyalkylene polymer may be used alone, or two or more types of oxyalkylene polymers may be used. When the polymer B is composed of two or more types of oxyalkylene polymers, the average number of hydroxyl groups per molecule of the polymer B is not particularly limited, but is preferably 0.1 to 1.0, more preferably 0.5 to 1.0, and particularly preferably 0.8 to 1.0. The number of hydroxyl groups of the polymer B, like the polymer A, is １３ This can be confirmed by identifying the type and amount of the initiator used in the synthesis by C-NMR measurement.

[0063] The Mn of polymer B is not particularly limited, but from the viewpoints of forming a pressure-sensitive adhesive layer with good flexibility, good adhesive strength of the pressure-sensitive adhesive, and suppression of adhesive residue, it is preferably 4,000 to 30,000, more preferably 4,500 to 25,000, and particularly preferably 5,000 to 20,000. The Mw / Mn of polymer B is not particularly limited, but from the viewpoints of being close to 1 and having a narrow molecular weight distribution, the hydroxyl-terminated urethane prepolymer is less likely to become highly viscous and synthesis efficiency is improved, it is preferably less than 1.20, more preferably less than 1.13, and particularly preferably less than 1.10. The degree of unsaturation of polymer B is also not particularly limited, but from the viewpoints of good curing properties of the hydroxyl-terminated urethane prepolymer and suppression of adhesive residue in the pressure-sensitive adhesive layer, it is preferably 0.015 meq / g or less, more preferably 0.013 meq / g or less, and particularly preferably 0.010 meq / g or less, with values ​​closer to 0 meq / g being preferable. When polymer B is composed of two or more kinds of oxyalkylene polymers, it is preferable that each of the oxyalkylene polymers has Mn, Mw / Mn and degree of unsaturation within the above ranges.

[0064] The synthesis method of polymer B is not particularly limited, and can be obtained, for example, by ring-opening addition polymerization of a compound having a cyclic ether structure, preferably an alkylene oxide, with an initiator having one active hydrogen in the presence of a catalyst. The compound having a cyclic ether structure is the same as that described for polymer A. Preferably, PO is used alone, or EO and PO are used in combination.

[0065] The average content of EO units in polymer B is not particularly limited, but from the viewpoint of obtaining a pressure-sensitive adhesive having a good balance between adhesive strength to skin and adhesive strength to a device and having suppressed crystallinity, it is preferably 0 to 80 mass%, more preferably 0 to 60 mass%, and particularly preferably 0 to 50 mass%. The average content of EO units in polymer B can be determined in the same manner as for polymer A.

[0066] Examples of the group having an active hydrogen in the initiator include the same as those in the case of Polymer A. These may be used alone, or two or more may be used in combination. Among these, a hydroxyl group is preferred, and an alcoholic hydroxyl group is more preferred. As the initiator having one hydroxyl group, from the viewpoint of ease of availability, for example, monohydric alcohols having 2 to 4 carbon atoms such as n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, and tert-butanol are preferred. These may be used alone, or two or more may be used in combination. Among these, n-butanol, sec-butanol, isobutanol, and tert-butanol are preferred. The ring-opening addition polymerization can be carried out by a known method, as in the case of Polymer A.

[0067] The content of polymer B is not particularly limited, but from the same viewpoint, it is preferably 5 to 40 parts by mass, more preferably 10 to 35 parts by mass, and particularly preferably 10 to 20 parts by mass, per 100 parts by mass of the total of polymer A1, polymer A2, and polymer B in the oxyalkylene polymer.

[0068] -Diisocyanate Compound- The diisocyanate compound used in the synthesis of the hydroxyl group-terminated urethane prepolymer is an organic compound having two isocyanate groups per molecule. There are no particular limitations on the diisocyanate compound, and examples include aliphatic diisocyanate compounds, alicyclic diisocyanate compounds, aromatic diisocyanate compounds, and araliphatic diisocyanate compounds. These may be used alone or in combination of two or more.

[0069] The aliphatic diisocyanate compound may be either linear or branched. The aliphatic diisocyanate compound is not particularly limited, and examples thereof include tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, and 3-methylpentane-1,5-diisocyanate. These may be used alone or in combination of two or more. The alicyclic diisocyanate compound is not particularly limited, and examples thereof include isophorone diisocyanate (IPDI), hydrogenated xylylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate (HMDI), 1,4-cyclohexane diisocyanate, methylcyclohexylene diisocyanate, and 1,3-bis(isocyanatomethyl)cyclohexane. These may be used alone or in combination of two or more. The aromatic diisocyanate compound is not particularly limited, and examples thereof include tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), 4,4'-dibenzyl diisocyanate, 1,5-naphthylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, dialkyldiphenylmethane diisocyanate, and tetraalkyldiphenylmethane diisocyanate. These may be used alone, or two or more may be used in combination. The aromatic aliphatic diisocyanate compound is not particularly limited, and examples thereof include xylylene diisocyanate and tetramethylxylylene diisocyanate (TMXDI). These may be used alone, or two or more may be used in combination. Among these, from the viewpoint of obtaining a pressure-sensitive adhesive layer having good curability of the hydroxyl group-terminated urethane prepolymer and good flexibility, HDI, IPDI, HMDI and TMXDI are preferred, and HDI is more preferred.

[0070] Furthermore, as the diisocyanate compound, a bifunctional isocyanate-terminated urethane prepolymer obtained by previously reacting the above-mentioned diisocyanate compound with a diol (for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, etc.) can also be used.

[0071] -Tin-free catalyst- A tin-free catalyst is a urethane-forming catalyst that does not contain tin. From the viewpoint of obtaining a low-toxicity, skin-friendly adhesive, it is preferable that the adhesive does not contain tin or tin compounds.

[0072] The tin-free catalyst is not particularly limited, and examples thereof include tertiary amine catalysts and organometallic catalysts containing metals other than tin. These may be used alone or in combination of two or more. Among these, organometallic catalysts are preferred from the viewpoint of better reaction promotion. The metal contained in the organometallic catalyst containing a metal other than tin is not particularly limited, and examples thereof include zinc, bismuth, titanium, lead, iron, cobalt, and zirconium. These may be used alone or in combination of two or more. Among these, zinc and bismuth are preferred, and zinc is more preferred from the viewpoint of low toxicity to the skin, ease of handling, etc.

[0073] The tertiary amine catalyst is not particularly limited, and examples thereof include triethylamine, triethylenediamine, 1,8-diazabicyclo[5.4.0]-7-undecene (DBU), and the like. These may be used alone, or two or more types may be used in combination. The organometallic catalyst containing a metal other than tin is not particularly limited, and examples thereof include zinc carboxylates such as zinc naphthenate and zinc 2-ethylhexanoate, zinc compounds such as zinc acetylacetonate, and the like; bismuth compounds such as bismuth 2-ethylhexanoate and bismuth neodecanoate, and the like; titanium compounds such as dibutyltitanium dichloride, tetrabutyltitanium, and butoxytitanium trichloride, and the like; lead compounds such as lead oleate, lead 2-ethylhexanoate, lead benzoate, and lead naphthenate, and the like; iron compounds such as iron 2-ethylhexanoate and iron acetylacetonate, and the like; cobalt compounds such as cobalt benzoate and cobalt 2-ethylhexanoate, and the like; and zirconium compounds such as zirconium naphthenate. These may be used alone or in combination of two or more.

[0074] The amount of the tin-free catalyst used in the reaction of the oxyalkylene polymer with the diisocyanate compound is not particularly limited, but from the viewpoint of a good reaction-accelerating effect and a reduction in the amount of residual metal components, the amount is preferably more than 0.001 part by mass and less than 0.05 part by mass, more preferably 0.005 to 0.045 parts by mass, and particularly preferably 0.01 to 0.04 parts by mass, relative to 100 parts by mass of the oxyalkylene polymer.

[0075] The method for producing the hydroxyl-terminated urethane prepolymer is not particularly limited, and examples thereof include a method in which an oxyalkylene polymer, a diisocyanate compound, a catalyst, and a solvent are all charged into a reaction vessel at once, and a method in which a diisocyanate compound is added dropwise or the like to a reaction vessel charged with an oxyalkylene polymer, a catalyst, and a solvent.As a method for producing the hydroxyl-terminated urethane prepolymer, a method in which a diisocyanate compound is added later is preferred from the viewpoint of ease of control of the molecular weight distribution of the hydroxyl-terminated urethane prepolymer due to preferential reaction of low-molecular-weight components in the synthetic raw materials.

[0076] The solvent used in the production of the hydroxyl-terminated urethane prepolymer is not particularly limited, and examples thereof include ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate; and aromatic hydrocarbons such as toluene and xylene. These may be used alone or in combination of two or more. When a solvent is used in the production of the hydroxyl-terminated urethane prepolymer, there are no particular limitations on the amount used, but from the viewpoints of uniformity of the reaction system and synthesis efficiency, the amount used is preferably 50 to 500 parts by mass, more preferably 70 to 400 parts by mass, and particularly preferably 80 to 300 parts by mass per 100 parts by mass of the oxyalkylene polymer in total.

[0077] The isocyanate index in the production of a hydroxyl-terminated urethane prepolymer (reaction of an oxyalkylene polymer with a diisocyanate compound) is not particularly limited, but from the viewpoint of efficiently obtaining a hydroxyl-terminated urethane prepolymer having an appropriate molecular chain length, it is preferably less than 100, more preferably 30 to 95, and particularly preferably 50 to 95.

[0078] The reaction temperature in producing the hydroxyl group-terminated urethane prepolymer is not particularly limited, but from the viewpoint of promoting the urethanization reaction and suppressing side reactions, it is preferably less than 100° C., more preferably 70 to 95° C., and particularly preferably 75 to 90° C. After completion of the reaction, a reaction terminator such as acetylacetone may be added to deactivate the catalyst.

[0079] The average number of hydroxyl groups per molecule of the hydroxyl-terminated urethane prepolymer is not particularly limited, but from the viewpoint of obtaining a pressure-sensitive adhesive having a good balance between adhesive strength to skin and adhesive strength to a device, it is preferably less than 3.0, more preferably 1.7 to 2.9, and particularly preferably 1.8 to 2.5.

[0080] <<Polyisocyanate Compound>> The polyisocyanate compound is a curing agent for the hydroxyl group-terminated urethane prepolymer. The polyisocyanate compound is a compound having two or more isocyanate groups per molecule, and may be used alone or in combination of two or more. As the polyisocyanate compound, from the viewpoints of availability and reactivity, a diisocyanate compound is preferred. Furthermore, from the viewpoints of good adhesive strength of the pressure-sensitive adhesive and suppression of adhesive residue, a polyisocyanate compound having three or more isocyanate groups per molecule is preferred.

[0081] Specific examples of diisocyanate compounds include the same as the specific examples of diisocyanate compounds constituting the above-mentioned hydroxyl group-terminated urethane prepolymer. These may be used alone, or two or more may be used in combination. Examples of polyisocyanate compounds having three or more isocyanate groups per molecule include isocyanurate-modified compounds, biuret-modified compounds, and allophanate-modified compounds, which are derivatives of the above-mentioned diisocyanate compounds, as well as trifunctional or higher isocyanate group-terminated urethane prepolymers (adducts), which are reaction products of diisocyanate compounds and polyols (e.g., trimethylolpropane) having three or more hydroxyl groups per molecule. These may be used alone, or two or more may be used in combination.

[0082] <<Tackifier Resin>> The PSA composition may contain a tackifier resin. There are no particular limitations on the tackifier resin, and the PSA composition may contain one or both of a tackifier resin having a softening point of 70°C or higher and a tackifier resin having a softening point below 70°C. However, the PSA composition preferably contains a tackifier resin having a softening point of 70°C or higher, and more preferably a tackifier resin having a softening point of 70°C or higher. By including a tackifier resin having a softening point of 70°C or higher, it is easy to obtain a PSA that has sufficient adhesive strength and is reduced in residue on the skin when peeled from the skin.

[0083] Specific examples of tackifier resins include, but are not limited to, rosin-based tackifier resins, terpene-based tackifier resins, hydrocarbon-based tackifier resins, styrene-based tackifier resins, and acrylic tackifier resins. These may be used alone or in combination of two or more. Among these, terpene-based tackifier resins and styrene-based tackifier resins are preferred from the viewpoint of improving adhesive strength to skin and SUS steel sheets. Terpene-based tackifier resins are more preferred from the viewpoint of good adhesive strength to phenolic resins. Furthermore, styrene-based tackifier resins are more preferred from the viewpoint of reducing coloration of the adhesive. The adhesive composition according to this embodiment can suitably contain either a tackifier resin having a hydroxyl group or a tackifier resin not having a hydroxyl group. However, from the viewpoint of appropriately suppressing adhesive strength to skin and further improving water resistance, a tackifier resin not having a hydroxyl group is preferably used. The adhesive composition according to this embodiment does not necessarily need to contain a tackifier resin not having a hydroxyl group.

[0084] - Rosin-Based Tackifying Resin - Specific examples of rosin-based tackifying resins are not particularly limited and include, for example, unmodified rosins (raw rosins) such as gum rosin, wood rosin, and tall oil rosin; modified rosins obtained by modifying these unmodified rosins through hydrogenation, disproportionation, polymerization, etc. (hydrogenated rosin, disproportionated rosin, polymerized rosin, other chemically modified rosins, etc.; the same applies hereinafter); and various other rosin derivatives. These may be used alone or in combination of two or more. Specific examples of the rosin derivative include, but are not limited to, rosin esters such as those obtained by esterifying unmodified rosin with alcohols (i.e., rosin esters) and those obtained by esterifying modified rosin with alcohols (i.e., modified rosin esters); unsaturated fatty acid-modified rosins obtained by modifying unmodified or modified rosin with unsaturated fatty acids; unsaturated fatty acid-modified rosin esters obtained by modifying rosin esters with unsaturated fatty acids; rosin alcohols obtained by reducing the carboxyl groups of unmodified rosin, modified rosin, unsaturated fatty acid-modified rosin, or unsaturated fatty acid-modified rosin esters; metal salts of rosins (especially rosin esters), such as unmodified rosin, modified rosin, and various rosin derivatives; and rosin phenolic resins obtained by adding phenol to rosins (unmodified rosin, modified rosin, various rosin derivatives, etc.) using an acid catalyst and then thermally polymerizing the resulting resins. These may be used alone or in combination. Among these, rosin ester-based tackifying resins are preferred.

[0085] The rosin-based tackifying resin may be a commercially available product. Specific examples of commercially available rosin-based tackifying resins include, but are not limited to, "HARIESTER TF," "HARIESTER S," "NEOTALL G2," "NEOTALL 101N," "NEOTALL 125HK," "HARITACK 8LJA," "HARITACK ER95," "HARITACK SE10," "HARITACK PH," "HARITACK F85," "HARITACK F105," "HARITACK FK100," "HARITACK FK125," and "HARITACK PCJ," all manufactured by Harima Chemicals Co., Ltd.; and "Foral 105-E," "Foral 85-E," and "Foral" manufactured by Eastman Chemical Company. "AX-E" manufactured by Arakawa Chemical Industries, Ltd.; "Superester A-75", "Superester A-100", "Superester A-115", "Superester A-125", "Pensel A", "Pensel AZ", "Pensel C", "Pensel D-125", "Pine Crystal KE-100", "Pine Crystal KE-311", "Pine Crystal KE-359", "Pine Crystal KE-604", and "Pine Crystal KR-140" manufactured by GUANGDONG KOMO Co., Ltd. Examples include "KF382S", "KF392S", "KF364", "KF384S", "KF394S", "KF398S", "KF399S", "KF452S", "KF462S", "KF454S", "KF464S", "KP120", "KP130", "KP140", "KP150", "K107", and "K108".

[0086] -Terpene-Based Tackifying Resin- Specific examples of terpene-based tackifying resins include, but are not limited to, terpene resins such as α-pinene polymers, β-pinene polymers, and dipentene polymers; and modified terpene resins obtained by modifying these terpene resins (such as phenol-modified, aromatic-modified, hydrogenated, and hydrocarbon-modified). These may be used alone, or two or more may be used in combination. Specific examples of the modified terpene resins include, but are not limited to, terpene-modified phenolic resins, aromatic-modified terpene resins (such as styrene-modified terpene resins), and hydrogenated terpene resins. These may be used alone, or two or more may be used in combination. Among these, aromatic-modified terpene resins are preferred. Commercially available terpene-based tackifying resins can be used. Specific examples of commercially available terpene-based tackifying resins include, but are not limited to, YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd.).

[0087] -Hydrocarbon-Based Tackifying Resin- Specific examples of hydrocarbon-based tackifying resins are not particularly limited, and include various hydrocarbon resins such as aliphatic (C5) petroleum resins, aromatic (C9) petroleum resins, aliphatic / aromatic copolymer (C5 / C9) petroleum resins, hydrogenated products thereof (e.g., alicyclic petroleum resins (alicyclic saturated hydrocarbon resins) obtained by hydrogenating aromatic petroleum resins), various modified products thereof (e.g., maleic anhydride modified products), coumarone resins, and coumarone-indene resins. These may be used alone or in combination of two or more. Among these, alicyclic saturated hydrocarbon resins are preferred. Commercially available hydrocarbon-based tackifying resins can be used. Specific examples of commercially available hydrocarbon-based tackifying resins are not particularly limited, and include, for example, Alcon M115 (manufactured by Arakawa Chemical Industries, Ltd.).

[0088] - Styrene-based tackifying resin - Specific examples of styrene-based tackifying resins are not particularly limited and include, for example, styrene homopolymers, α-methylstyrene homopolymers, α-methylstyrene / styrene copolymers, styrene / aliphatic copolymers, α-methylstyrene / styrene / aliphatic copolymers, C9 petroleum resins, C5 / C9 petroleum resins, phenol-modified styrene resins, and hydrogenated products thereof. These may be used alone or in combination of two or more.

[0089] Among these, in terms of excellent compatibility with the (meth)acrylic block copolymer, styrene homopolymer, α-methylstyrene homopolymer, α-methylstyrene / styrene copolymer, styrene / aliphatic polymer, α-methylstyrene / styrene / aliphatic copolymer, phenol-modified styrene resin, and partially hydrogenated products thereof are preferred, styrene homopolymer, α-methylstyrene homopolymer, α-methylstyrene / styrene copolymer, and partially hydrogenated products thereof are more preferred, and styrene homopolymer is particularly preferred.

[0090] As the styrene-based tackifying resin, commercially available products can be used. Specific examples of commercially available styrene-based tackifying resins are not particularly limited, and include, for example, "SYLVARES SA-85," "SYLVARES SA-100," "SYLVARES SA-120," "SYLVARES SA-140," and "SYLVARES 520" manufactured by Arizona Chemical Company; "ESCOLETZ ECR-213" and "ESCOLETZ ECR-807" manufactured by ExxonMobil Corporation; and "YS Resin" manufactured by Yasuhara Chemical Co., Ltd. SX100"; "FTR0100", "FTR2120", "FTR2140", "FTR6100", "FTR6110", "FTR6125", "FTR7100", "FTR8100", "FTR8120", and "FMR0150" manufactured by Mitsui Chemicals, Inc.; and "Kristalex F85", "Kristalex F100", "Kristalex F115", "Kristalex 1120", "Kristalex 3070", "Kristalex 3085", "Kristalex 3100", and "Kristalex 5140" manufactured by Eastman Chemical Company.

[0091] -Acrylic Tackifying Resin- Specific examples of acrylic tackifying resins are not particularly limited and include, for example, acrylic tackifying resins based on acrylic polymers (homopolymers or copolymers) using one or more (meth)acrylic acid alkyl esters as a monomer component. Specific examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and methyl (meth)acrylate. Examples of (meth)acrylic acid C1-20 alkyl esters include nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate. These may be used alone or in combination of two or more. Among these, (meth)acrylic acid alkyl esters having a linear or branched alkyl group having 4 to 18 carbon atoms are preferably used.

[0092] The acrylic polymer may contain, as necessary, units corresponding to other monomer components copolymerizable with the alkyl (meth)acrylate.

[0093] The amount of tackifier resin used per 100 parts by mass of hydroxyl group-terminated urethane prepolymer is not particularly limited, but from the viewpoint of obtaining a PSA that has sufficient adhesive strength to devices and sealants and also has sufficient long-term water resistance, it is preferably 0.5 to 150 parts by mass, more preferably 1.0 to 100 parts by mass, even more preferably 3.0 to 50 parts by mass, and particularly preferably 5.0 to 40 parts by mass.

[0094] <<Other Components>> The PSA composition may contain other components in addition to the hydroxyl group-terminated urethane prepolymer, polyisocyanate compound, and tackifying resin. Examples of other components include liquid or paste-like components, and various additives such as plasticizers, antioxidants, antistatic agents, fillers, UV absorbers, light stabilizers, conductivity-imparting agents, leveling agents, antibacterial agents, disinfectants, and softeners. A solvent may also be contained. The other components may be used alone or in combination of two or more, and may be blended in an amount within a range that does not impair the effects of the present invention.

[0095] The total content of the hydroxyl group-terminated urethane prepolymer and the polyisocyanate compound in the pressure-sensitive adhesive composition (excluding the solvent) is not particularly limited, but from the viewpoint of fully exerting the effects of the present invention, it is preferably 85% by mass or more, more preferably 90% by mass or more, particularly preferably 95% by mass or more, and is also preferably 100% by mass.

[0096] The content of the hydroxyl group-terminated urethane prepolymer relative to the total of the hydroxyl group-terminated urethane prepolymer and the polyisocyanate compound is not particularly limited, but from the viewpoint of fully exerting the effects of the present invention, it is preferably 50 to 98 mass%, more preferably 60 to 95 mass%, and particularly preferably 70 to 93 mass%.

[0097] The content of the polyisocyanate compound relative to the total of the hydroxyl group-terminated urethane prepolymer and the polyisocyanate compound is not particularly limited, but from the viewpoint of fully exerting the effects of the present invention, it is preferably 2 to 50 mass%, more preferably 5 to 40 mass%, and particularly preferably 7 to 30 mass%.

[0098] The plasticizer is not particularly limited and can be selected from the viewpoints of compatibility with other components and wettability of the pressure-sensitive adhesive layer to the adherend. Examples include fatty acid esters having 8 to 30 carbon atoms and phosphate esters. These may be used alone or in combination of two or more. The antioxidant is not particularly limited and examples include phenol-based, amine-based, sulfur-based, and phosphorus-based antioxidants that contribute to suppressing thermal degradation of the pressure-sensitive adhesive layer. These may be used alone or in combination of two or more. Among these, phenol-based antioxidants are preferred from the viewpoint of low toxicity to the skin. The antistatic agent is not particularly limited and examples include inorganic salts; ionic liquids containing imidazolium ions, pyridinium ions, ammonium ions, etc.; surfactants; and other compounds that contribute to suppressing damage to circuit patterns due to electrostatic discharge. These may be used alone or in combination of two or more. The filler is not particularly limited and examples include talc, calcium carbonate, and titanium oxide. These may be used alone or in combination of two or more. The ultraviolet absorber is not particularly limited, and examples thereof include benzophenone-based, benzotriazole-based, salicylic acid-based, oxalic acid anilide-based, cyanoacrylate-based, and triazine-based ultraviolet absorbers. These may be used alone or in combination of two or more. The light stabilizer is not particularly limited, and examples thereof include hindered amine-based light stabilizers and ultraviolet stabilizers. These may be used alone or in combination of two or more. The conductivity imparting agent is not particularly limited, and examples thereof include metal microparticles such as silver nanoparticles. These may be used alone or in combination of two or more. The leveling agent is not particularly limited, and examples thereof include polymer-based leveling agents such as acrylic, vinyl, silicone, and fluorine-based. These may be used alone or in combination of two or more.

[0099] The method for producing a pressure-sensitive adhesive composition involves reacting an oxyalkylene polymer and a diisocyanate compound in the presence of a tin-free catalyst to obtain a hydroxyl-terminated urethane prepolymer, and then mixing the hydroxyl-terminated urethane prepolymer with a polyisocyanate compound to produce the pressure-sensitive adhesive composition. The hydroxyl-terminated urethane prepolymer is reacted with a polyisocyanate compound to preferably obtain a urethane-based pressure-sensitive adhesive. When mixing the hydroxyl-terminated urethane prepolymer with the polyisocyanate compound, a tackifying resin and other components that may be contained in the pressure-sensitive adhesive composition described above may also be mixed.

[0100] <Method for producing adhesive layer> In one embodiment of the skin patch of the present invention, a urethane-based adhesive obtained by curing the above-mentioned adhesive composition can be used as the adhesive layer. The urethane-based adhesive is obtained as a reaction product between a hydroxyl group-terminated urethane prepolymer in the adhesive composition and a polyisocyanate compound. As described below, for example, the adhesive composition can be applied to a substrate and cured to form the urethane-based adhesive as an adhesive layer.

[0101] Depending on the manner of use of the pressure-sensitive adhesive layer, the pressure-sensitive adhesive composition may be a one-component type in which a hydroxyl group-terminated urethane prepolymer and a polyisocyanate compound as a curing agent are pre-mixed, or may be a two-component type consisting of a first part containing a hydroxyl group-terminated urethane prepolymer and a second part containing a polyisocyanate compound as a curing agent.

[0102] In the reaction between the hydroxyl-terminated urethane prepolymer and the polyisocyanate compound, a catalyst and a solvent may be used as necessary. When a catalyst is used, the urethane-forming catalyst, which is a non-tin-containing catalyst as described above, can be used. The catalyst may be the same as or different from the catalyst used in the synthesis of the hydroxyl-terminated urethane prepolymer. If the catalyst used in the synthesis of the hydroxyl-terminated urethane prepolymer remains, the remaining catalyst may also exert a catalytic effect in the reaction between the hydroxyl-terminated urethane prepolymer and the polyisocyanate compound. When a catalyst is added during the reaction between the hydroxyl-terminated urethane prepolymer and the polyisocyanate compound, the amount added is not particularly limited, but is preferably more than 0.001 parts by mass and less than 0.05 parts by mass, more preferably 0.005 to 0.045 parts by mass, and particularly preferably 0.01 to 0.04 parts by mass, per 100 parts by mass of the hydroxyl-terminated urethane prepolymer and the polyisocyanate compound combined. When a catalyst is added, it is preferable to add a reaction terminator to deactivate the catalyst after completion of the reaction.

[0103] Examples of solvents used in the reaction between the hydroxyl-terminated urethane prepolymer and the polyisocyanate compound include those similar to those used in the synthesis of the hydroxyl-terminated urethane prepolymer described above. The solvent may be the same as or different from that used in the synthesis of the hydroxyl-terminated urethane prepolymer. If any solvent remains from the synthesis of the hydroxyl-terminated urethane prepolymer, it may be used as is. When a solvent is used, the amount used is not particularly limited, but is preferably 50 to 500 parts by mass, more preferably 70 to 400 parts by mass, and particularly preferably 80 to 300 parts by mass per 100 parts by mass of the total of the hydroxyl-terminated urethane prepolymer and the polyisocyanate compound.

[0104] The reaction temperature between the hydroxyl group-terminated urethane prepolymer and the polyisocyanate compound is not particularly limited, but from the viewpoint of promoting the urethanization reaction and suppressing side reactions, it is preferably less than 120°C, more preferably 40 to 110°C, and particularly preferably 50 to 100°C.

[0105] The isocyanate index of the polyisocyanate compound to be reacted with the hydroxyl group-terminated urethane prepolymer is not particularly limited, but is preferably greater than 100, more preferably 101 to 1,500, and particularly preferably 105 to 1,000.

[0106] The formation of the pressure-sensitive adhesive layer is not particularly limited and can be performed using a known method. Examples include a method of applying a pressure-sensitive adhesive composition to a release liner, curing the composition to form a pressure-sensitive adhesive layer, and then laminating a substrate; a method of applying a pressure-sensitive adhesive composition to a substrate, curing the composition to form a pressure-sensitive adhesive layer, and then laminating a release liner; and the like. These methods may be used alone, or two or more types may be used in combination. Alternatively, a pressure-sensitive adhesive layer may be initially formed only on a portion of the substrate to form a partial pressure-sensitive adhesive layer, or a pressure-sensitive adhesive layer may be initially formed over the entire substrate and then partially removed to form a partial pressure-sensitive adhesive layer. The method of applying the pressure-sensitive adhesive composition is not particularly limited, and known methods such as bar coating, knife coating, roll coating, blade coating, die coating, microgravure coating, comma coating, slot die coating, lip coating, and cast coating can be used. These methods may be used alone, or two or more types may be used in combination. After application, the pressure-sensitive adhesive composition is preferably cured by, for example, hot air drying at 40 to 80°C to sufficiently volatilize the solvent contained in the pressure-sensitive adhesive composition, thereby forming the pressure-sensitive adhesive layer.

[0107] The pressure-sensitive adhesive layer is preferably subjected to a crosslinking treatment to impart an appropriate cohesive force. Crosslinking treatments include physical crosslinking by irradiation with ionizing radiation such as electron beams, gamma rays, and X-rays, and chemical crosslinking using a crosslinking agent. From the viewpoint of good handling and reproducibility, chemical crosslinking using a crosslinking agent is preferred. For example, a crosslinking agent is added to a pressure-sensitive adhesive composition containing the materials constituting the pressure-sensitive adhesive layer, followed by heat treatment to perform the crosslinking treatment. As such a crosslinking agent, crosslinking agents used in crosslinking treatments such as isocyanate-based crosslinking agents, peroxide-based crosslinking agents, and metal chelate-based crosslinking agents can be used.

[0108] The adhesive layer crosslinked as described above maintains a suitable balance between skin adhesion and cohesion depending on the degree of crosslinking, but the molecular weight and molecular weight distribution of the urethane-based adhesive also affect these adjustments.

[0109] When the skin patch of the present embodiment has a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) partially formed on one side (first surface) of the substrate and another pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) formed on the other side (second surface) of the substrate, the thickness of the second pressure-sensitive adhesive layer is not particularly limited, but is preferably 30 to 80 μm, more preferably 40 to 70 μm. The second pressure-sensitive adhesive layer may be partially formed on the second surface of the substrate, or may be formed over the entire second surface of the substrate. The pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer is not particularly limited, and examples thereof include urethane-based pressure-sensitive adhesives, acrylic-based pressure-sensitive adhesives, silicone-based pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives (natural rubber-based, synthetic rubber-based, and mixtures thereof), polyester-based pressure-sensitive adhesives, polyether-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives. These may be used alone or in combination of two or more types.

[0110] The skin patch of this embodiment may include layers other than the substrate and adhesive layer as long as the effects of the present invention are achieved. Furthermore, in the skin patch of this embodiment, it is preferable that the adhesive layer is protected until use to prevent contamination of the surface of the adhesive layer. One method for protecting the adhesive is to attach a release liner to the adhesive layer. Furthermore, when only one side is adhesive, the side of the substrate on which the adhesive layer is not formed may be release-treated, and the adhesive layer may be attached to this side, and the skin patch may be rolled up to protect the adhesive layer. Additionally, when both sides are adhesive, one release-treated side of a release liner having release-treated surfaces on both sides may be attached to one adhesive side, and the skin patch may be rolled up so that the other release-treated side of the release liner is in contact with the other adhesive side, thereby protecting both adhesive layers.

[0111] [Electronic device] By attaching the above-mentioned skin patch material to an electronic device, an electronic device can be provided with the above-mentioned skin patch material. When the above-mentioned skin patch material has excellent flexibility, the electronic device may be any of a rigid device, a semi-flexible device, and a flexible device, but a flexible device is preferred.

[0112] The flexible device to be attached to the skin is not particularly limited, and examples thereof include biosensors, environmental sensors, etc. These may be used alone, or two or more types may be used in combination. The detection target of the biosensor is not particularly limited, and examples thereof include cardiac potential, pulse wave, acceleration, heart rate interval, pulse rate interval, respiratory rate, electrocardiogram, electromyogram, activity level, blood pressure, body temperature, electroencephalogram, etc. These may be used alone, or two or more types may be used in combination.

[0113] The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples and various modifications are possible within the scope of the present invention. In the following, "parts" and "%" mean "parts by mass" and "% by mass", respectively.

[0114] [Preparation of Substrate] A polyurethane foam sheet (product name: HYDROPHILIC FORM 1012, manufactured by Freudenberg GmbH) was prepared as the substrate. The substrate was a porous sheet having open cells.

[0115] [Evaluation of the substrate] The substrate was measured for (1) thickness, (2) density, (3) porosity, (4) breaking strength, and (5) breaking elongation as follows, and the results were as follows: (1) Thickness: 1360 μm (2) Density: 0.120 g / cm ３ (3) Pore content: 88% (4) Breaking strength: 1.40 (N / 20 mm) (5) Breaking elongation: 273%

[0116] (Thickness) The thickness of each of the substrates was measured at five points using a dial gauge, and the average value of the measurement results was taken as the thickness of each substrate.

[0117] (Density) The substrate was cut into a piece of 5 cm x 5 cm and the weight was measured. The density was calculated using the measured weight and the thickness according to the following formula: Density (g / cm ３ ) = weight (g) / (5 x 5 x thickness (cm ３ ))

[0118] (Porosity) The porosity of the substrate was calculated using the following formula: Porosity (%) = (1 x specific gravity - density of substrate material) x 100

[0119] (Breaking Strength, Breaking Elongation) The substrate was cut into a width of 20 mm and a length of 100 mm, and placed in a tensile tester (product name: Autograph AG-IS, manufactured by Shimadzu Corporation) with a chuck distance of 40 mm, and pulled at a tensile speed of 300 mm / min to measure the load and elongation at break. Similar measurements were performed three times, and the average values ​​were taken as the breaking strength and breaking elongation of each substrate.

[0120] [Measurement Methods] The methods for measuring various physical properties in the following synthesis examples are as follows.

[0121] <Number average molecular weight (Mn) and weight average molecular weight (Mw)> Mn and Mw were measured by gel permeation chromatography (GPC) under the following measurement conditions (polystyrene equivalent), and the molecular weight distribution (Mw / Mn) was calculated from these values. [Measurement conditions] - Instrument used: "HLC-8320GPC", manufactured by Tosoh Corporation - Column used: "TSKgel (registered trademark) SuperMultiporeHZ-M", manufactured by Tosoh Corporation - Detector: Refractive index (RI) detector - Detection temperature: 40°C - Eluent: Tetrahydrofuran - Flow rate: 0.350 mL / min - Sample concentration: 0.5% by mass - Sample injection amount: 10 μL - Standard sample: Polystyrene

[0122] <Ethylene oxide (EO) unit content> The EO unit content of each oxyalkylene polymer was determined based on the amounts of propylene oxide (PO) and EO used in the synthesis, and the amount of EO charged was considered to be the EO unit content in the oxyalkylene polymer. The EO unit content of the hydroxyl group-terminated urethane prepolymer was determined as the weighted average of the EO unit contents in each of the raw material components.

[0123] <Hydroxyl Value> The hydroxyl value was determined in accordance with Method B (automatic potentiometric titration) of JIS K 1557-1:2007.

[0124] <Degree of Unsaturation> The degree of unsaturation was measured in accordance with JIS K 1557-3:2007.

[0125] <Average number of hydroxyl groups per molecule of oxyalkylene polymer A> The average number of hydroxyl groups per molecule of oxyalkylene polymer A was determined by calculating the weighted average of the numbers of hydroxyl groups per molecule of oxyalkylene polymers A1 and A2 used as oxyalkylene polymer A (the number of hydroxyl groups per molecule of the initiator used in the synthesis of each oxyalkylene polymer) based on the blending amount of each oxyalkylene polymer.

[0126] <Average Number of Hydroxyl Groups per Molecule of Hydroxyl-Terminated Urethane Prepolymer> The number of hydroxyl groups per molecule of each oxyalkylene polymer (oxyalkylene polymers A1, A2, and B) used in the synthesis of the hydroxyl-terminated urethane prepolymer was weighted and averaged based on the blending amount of each oxyalkylene polymer, and this value was considered to be the average number of hydroxyl groups per molecule of the hydroxyl-terminated urethane prepolymer.

[0127] [Materials Used] Details of the synthesis examples and materials used in the examples are shown below. TBA-DMC catalyst: zinc hexacyanocobaltate complex with tert-butanol as a ligand Glycerin Propylene glycol n-butanol Propylene oxide (PO) Ethylene oxide (EO) Adsorbent: synthetic magnesium silicate; Kyoward (registered trademark) 600S, manufactured by Kyowa Chemical Industry Co., Ltd. Urethane catalyst: zinc (Zn)-containing urethane catalyst (zinc carboxylate); K-KAT XK627, manufactured by KING INDUSTRIES Diisocyanate compound: hexamethylene diisocyanate (HDI), Duranate (registered trademark) 50M-HDI, manufactured by Asahi Kasei Corporation Toluene Ethyl acetate Curing agent (polyisocyanate compound): HDI-based polyisocyanate, Duranate E402-80B, manufactured by Asahi Kasei Corporation; solid content: approximately 80% by mass; Base material: polyurethane (PU)

[0128] [Synthesis of Oxyalkylene Polymer] (Synthesis Example 1-1) 1000 g of glycerin as an initiator and a TBA-DMC catalyst (metal concentration 46 ppm by mass) were placed in a pressure vessel, and the vessel was purged with nitrogen. The reaction solution was heated to 135°C while stirring, and 120 g of propylene oxide (PO) was added and reacted. After the temperature rise of the reaction solution stopped, it was cooled to 135°C, and while stirring the reaction solution, 3782.4 g of PO and 945.6 g of ethylene oxide (EO) were added to the vessel. After confirming that the internal pressure had stopped changing, an adsorbent was added, and neutralization and catalyst removal were performed to obtain oxyalkylene polymer 1-1, which is polymer A1.

[0129] Synthesis Example 1-2 Oxyalkylene polymer 1-2, which was polymer A2, was synthesized in the same manner as in Synthesis Example 1-1, except that the initiator in Synthesis Example 1-1 was changed from glycerin to propylene glycol.

[0130] Synthesis Example 1-3 An oxyalkylene polymer 1-3, which was polymer A1, was synthesized in the same manner as in Synthesis Example 1-1, except that EO was not added.

[0131] Synthesis Example 1-4 Oxyalkylene polymer 1-4, which was polymer A2, was synthesized in the same manner as in Synthesis Example 1-2, except that EO was not added.

[0132] Synthesis Example 1-5 Oxyalkylene polymer 1-5, which is polymer B, was synthesized in the same manner as in Synthesis Example 1-1, except that the initiator in Synthesis Example 1-1 was changed from glycerin to n-butanol, and after cooling the reaction solution, 2364 g of PO was added instead of EO. Table 1 shows various physical properties of oxyalkylene polymers 1-1 to 1-5.

[0133]

[0134] [Synthesis of hydroxyl group-terminated urethane prepolymer] (Synthesis Example 2-1) A reaction vessel equipped with a thermometer, a stirrer, and a cooling tube was charged with 36.0 parts by mass of oxyalkylene polymer 1-1, 48.0 parts by mass of oxyalkylene polymer 1-2, 16.0 parts by mass of oxyalkylene polymer 1-5, 50.6 parts by mass of toluene, and 50.6 parts by mass of ethyl acetate, and 0.038 parts by mass of a zinc (Zn)-containing urethanization catalyst was added, and the mixture was mixed at 40 ° C., followed by the addition of 1.7 parts by mass of HDI (isocyanate index 85), and the mixture was allowed to react at 80 ° C. The average number of hydroxyl groups per molecule of the blended oxyalkylene polymer A (oxyalkylene polymers A1 and A2) was 2.4, and the average number of hydroxyl groups per molecule of the oxyalkylene polymers (oxyalkylene polymers A1, A2, and B) was 2.2. The mixture was appropriately diluted with ethyl acetate and maintained at 80°C for 7 hours to allow the reaction to proceed, yielding a 50% by mass solution of a transparent hydroxyl-terminated urethane prepolymer U1 (average number of hydroxyl groups per molecule of oxyalkylene polymer (oxyalkylene polymers A1, A2, and B) 2.2, EO unit content 16.5% by mass).

[0135] Synthesis Example 2-2 A solution of hydroxyl-terminated urethane prepolymer U2 was produced in the same manner as in Synthesis Example 2-1 using the formulation shown in Table 2. The average number of hydroxyl groups per molecule of the oxyalkylene polymers (oxyalkylene polymers A1, A2, and B) of hydroxyl-terminated urethane prepolymer U2 was 2.2, and the EO unit content was 7.0%.

[0136] Table 2 shows the blending compositions of the oxyalkylene polymer, diisocyanate compound and catalyst in Synthesis Examples 2-1 and 2-2.

[0137]

[0138] [Production of Skin Patch for Evaluation] (Example 1) A liquid (adhesive composition) obtained by mixing 100 parts by mass of a 50% by mass solution of hydroxyl-terminated urethane prepolymer U1 and 5 parts by mass of a curing agent was degassed and then coated on a polyester film (thickness 38 μm) serving as a release liner using a knife coater, and wavy grooves with a width of 0.5 mm, an amplitude of 50 mm, a period of 140 mm, and a pitch of 5 mm were formed. The resulting coating was then dried at 100° C. for 2 minutes to form an adhesive layer with a thickness of 25 μm. The adhesive layer thus formed was then transferred and bonded to the plasma-treated surface of a substrate, and the resulting coating was left at 60° C. for 72 hours to obtain the skin patch of Example 1 (a skin patch having an adhesive layer formed only on one surface and no adhesive layer formed on the other surface).

[0139] (Examples 2 to 4) Skin patches of Examples 2 to 4 were prepared in the same manner as in Example 1, except that the thickness of the adhesive layer was changed as shown in Table 3.

[0140] (Examples 5 and 6) Skin patches of Examples 5 and 6 were prepared in the same manner as in Example 3, except that the adhesive layer shape was changed as shown in Table 3.

[0141] (Examples 7 to 9) Skin patches of Examples 7 to 9 were prepared in the same manner as Examples 2 to 4, respectively, except that the shape of the adhesive layer was changed to cover the entire surface.

[0142] (Examples 10 to 13) The skin patches of Examples 10 to 13 were prepared in the same manner as in Examples 3, 5, 6 and 8, respectively, except that the hydroxyl-terminated urethane prepolymer U1 was changed to the hydroxyl-terminated urethane prepolymer U2.

[0143] (Examples 14 to 17) The skin patches of Examples 14 to 17 were prepared in the same manner as in Examples 8, 3, 5, and 6, respectively, except that the liquid (urethane adhesive composition) obtained by mixing 100 parts by mass of a 50% solution of hydroxyl group-terminated urethane prepolymer U1 and 5 parts by mass of a curing agent was changed to 100 parts by mass of an acrylic adhesive solution (acrylic adhesive composition: solids content 40% by mass) prepared as follows: 100 parts by mass of an acrylic copolymer (a copolymer consisting of isononyl acrylate: 2-methoxyethyl acrylate: acrylic acid in a ratio of 65 parts by mass: 30 parts by mass: 5 parts by mass), 20 parts by mass of glyceryl tricaprylate, 10 parts by mass of a rosin ester (trade name: Halitack PCJ, manufactured by Harima Chemicals Co., Ltd.) as a tackifying resin, and 0.07 parts by mass of a trifunctional isocyanate compound (trade name: Coronate HL, manufactured by Tosoh Corporation) as a crosslinking agent were blended in toluene to prepare a uniform acrylic adhesive solution. 100 parts by mass of the prepared acrylic pressure-sensitive adhesive solution (solid content: 40% by mass) was used as an acrylic pressure-sensitive adhesive composition.

[0144] [Evaluation of Skin Patches] The following various evaluations were carried out for each of the skin patches produced in the above examples. The evaluation results are shown in Table 3. Examples 1 to 6 and 10 to 12 are working examples, and Examples 7 to 9 and 13 to 17 are comparative examples.

[0145] <Adhesive Strength> (1) To Phenol Resin One surface (first side) of a skin patch (100 mm long, 15 mm wide) from which the release liner had been peeled off, on which the adhesive layer had been formed, was placed on a phenolic resin plate ("SUMILITE (registered trademark) PL-1102", manufactured by Sumitomo Bakelite Co., Ltd.; 125 mm long, 30 mm wide, 2 mm thick), and the other surface (second side) of the skin patch, on which the adhesive layer had not been formed, was pressed against the phenolic resin plate using a rubber roller, which was moved back and forth once at a load of 2 kg and a speed of 300 mm / min. After leaving the skin patch to stand for 20 minutes, the adhesive strength when the adherend was a phenolic resin (to a phenolic resin) was measured by peeling the skin patch at a peel angle of 90° and a speed of 300 mm / min according to JIS Z 0237:2009. Table 3 shows the average of three measurements. The measured adhesive strength was evaluated according to the following criteria. The evaluation results are shown in Table 3. [Evaluation criteria (against phenolic resin)] A: 2.0 N / 15 mm or more B: 1.0 N / 15 mm or more but less than 2.0 N / 15 mm C: Less than 1.0 N / 15 mm In the cases of evaluations A and B, it can be said that the adhesive strength to phenolic resin boards, which are typical materials for sealing circuit patterns in wearable devices, is sufficient. On the other hand, in the case of evaluation C, the adhesive strength to phenolic resin was insufficient.

[0146] (2) To Skin In the above (1) To Phenol Resin, adhesive strength was measured in the same manner except that the phenolic resin plate was replaced with the skin of the forearm of humans (three subjects). The humans (three subjects) were (1) Gender: Male, Race: Japanese, Age: 30s, (2) Gender: Male, Race: Japanese, Age: 20s, and (3) Gender: Female, Race: Japanese, Age: 30s. Table 3 shows the average of three measurements. The measured adhesive strength was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 3. [Evaluation Criteria (To Skin)] A: 0.5 to 3.0 N / 15 mm B: Less than 0.5 N / 15 mm C: More than 3.0 N / 15 mm In the case of Evaluation A, the adhesive strength to the skin was adequate and could be said to be gentle on the skin. On the other hand, in the case of Evaluation B, the adhesive strength to the skin was insufficient. In addition, in the case of Evaluation C, the adhesive was difficult to peel from the skin and sometimes caused pain when peeling.

[0147] (3) Difference The difference in adhesive strength between the adherend made of phenolic resin (against phenolic resin) and the adherend made of skin on the forearm of a human (three subjects) (against skin) (adhesive strength to phenolic resin - adhesive strength to skin) was calculated and shown in Table 3. The calculated difference was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 3. [Evaluation criteria (difference)] A: 2.5 N / 15 mm or more B: 1.0 N / 15 mm or more but less than 2.5 N / 15 mm C: Less than 1.0 N / 15 mm

[0148] <Skin Observation> In an atmosphere of 23°C and 50% RH, a test piece of the patch (20 mm long, 15 mm wide) was applied to the skin of the forearm of humans (3 subjects). After 1 hour, the test piece was peeled off the skin, and the condition of the skin was visually observed. The observation results were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 3. [Evaluation criteria (skin observation)] A: No change from before application of the test piece. B: Some subjects noticed redness on the skin. C: Some subjects noticed residual glue (adhesive residue).

[0149] <Applied Feeling> Test samples were prepared by cutting each example of skin patch into 10 mm x 50 mm pieces. Next, the release paper was peeled off and the adhesive layer of the test sample was applied to the joint of the index finger of a test subject. The test subject then bent their index finger and evaluated the applied feeling according to the following criteria. The evaluation results are shown in Table 3. [Evaluation Criteria (Applied Feeling)] 5: No tightness felt at all 4: Tightness felt to an extent that it was not bothersome 3: Tightness felt slightly bothersome but to an extent that allowed daily life 2: Tightness felt bothersome but to an extent that allowed daily life without removing the patch 1: Tightness felt to an extent that was unbearable and required removal

[0150] <Amount of keratinocyte peeled after one day of application> In the same manner as in the measurement of "adhesion to skin" in the adhesive strength (2) above, the adhesive layer of the skin patch was pressed onto the skin of the forearm of humans (three subjects), the rest time after application of the skin patch was changed from 20 minutes to one day, and the skin patch was peeled off in the same manner as in the measurement of "adhesion to skin" in the adhesive strength (2) above. A measurement sample measuring 20 mm in length and 15 mm in width was cut out from the peeled skin patch, and the amount of keratinocyte peeled off (protein amount [mg / cm 2 ]) was measured using a "Protein Assay Lowry Kit" (manufactured by Nacalai Tesque, Inc.). ２ ]) was measured. The amount of keratin peeled after one day of application was evaluated according to the following evaluation criteria. Table 3 shows the average of three measurements. The measured amount of keratin peeled after one day of application was evaluated according to the following evaluation criteria. The evaluation results are shown in Table 3. [Evaluation criteria (amount of keratin peeled after one day of application)] A: 0.060 mg / cm ２ Below B: 0.060mg / cm ２ Very low C: Not measurable (peeling off) In the case of rating A, it can be said that the load of the first adhesive layer on the skin is sufficiently small. In the case of rating B, a large amount of keratin was peeled off, causing a large load on the skin and sometimes causing pain when peeling off. In the case of rating C, the patch could not be left on the skin for a day and peeled off midway, so it was not possible to evaluate.

[0151]

[0152] As can be seen from the evaluation results shown in Table 3, the skin patches of Examples 1 to 6 and 10 to 12 were found to have appropriate adhesive strength to the phenolic resin and to the skin. Furthermore, the skin patches of Examples 1 to 6 and 10 to 12 were found to have little adhesive residue. Furthermore, the skin patches of Examples 1 to 6 and 10 to 12 were found to have a good adhesive feel. Furthermore, the skin patches of Examples 1 to 6 and 10 to 12 were found to have little keratin peeling after one day of application, indicating that they are gentle on the skin. Furthermore, Examples 1 to 6, which used hydroxyl-terminated urethane prepolymer U1, are more preferable than Examples 10 to 12, which used hydroxyl-terminated urethane prepolymer U2, in that they have a larger difference in adhesive strength.

[0153] The above describes a preferred embodiment of the present invention, but the present invention is not limited to the above-described embodiment, and various modifications and substitutions can be made to the above-described embodiment without departing from the scope of the present invention.

[0154] 10, 110, 210 Skin patch 20, 120, 220 Substrate 30, 130, 230 Adhesive layer (first adhesive layer) 140 Other adhesive layer (second adhesive layer) 150, 250 Skin 160, 260 Wearable device

Claims

1. A skin patch having a base material and an adhesive layer, wherein the adhesive layer contains a urethane-based adhesive and is partially formed on at least one side of the base material.

2. The skin patch according to claim 1, wherein the adhesive layer is formed in a dot shape, a lattice shape, a linear shape, or a wavy line shape.

3. The skin patch according to claim 1 or 2, wherein the adhesive layer has an average content of structural units based on ethylene oxide of 60% by mass or less.

4. The skin patch according to claim 1 or 2, wherein the urethane-based adhesive is a cured product of an adhesive composition containing a hydroxyl-terminated urethane prepolymer and a polyisocyanate compound.

5. The skin patch according to claim 4, wherein the adhesive composition has an average content of structural units based on ethylene oxide of 60% by mass or less.

6. The skin patch according to claim 4, wherein the hydroxyl-terminated urethane prepolymer is a reaction product of an oxyalkylene polymer and a diisocyanate compound in the presence of a tin-free catalyst.

7. The skin patch according to claim 6, wherein the tin-free catalyst contains at least one of zinc and bismuth.

8. The skin patch according to claim 6, wherein the oxyalkylene polymer has an average content of structural units based on ethylene oxide of 60% by mass or less.

9. The skin patch according to claim 6, wherein the oxyalkylene polymer has an average number of hydroxyl groups per molecule of 1.5 to 3.

0.

10. The skin patch according to claim 6, wherein the oxyalkylene polymer contains an oxyalkylene polymer A having an average number of hydroxyl groups per molecule of 2.0 or more and an oxyalkylene polymer B having one hydroxyl group per molecule.

11. The skin patch according to claim 10, wherein the oxyalkylene polymer A contains an oxyalkylene polymer A1 having three hydroxyl groups per molecule and an oxyalkylene polymer A2 having two hydroxyl groups per molecule.

12. An electronic device provided with the skin patch according to claim 1 or 2.

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