Adhesive film and method for applying the same

Abstract

To provide an adhesive film capable of obtaining an excellent water stain decomposition effect and further to provide a method for attaching such an adhesive film.SOLUTION: There is provided an adhesive film which has a base material and an adhesive layer provided on one surface side of the base material, wherein the adhesive layer contains an organic acid having a function of decomposing water stains adhered to an adherend.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an adhesive film and a method for applying an adhesive film. [Background technology]

[0002] Tap water adheres to places where water is used, such as bathroom walls, window panes, and mirrors. When the water dries, limescale forms on the surface. This limescale is difficult to remove even with cleaning agents such as bathroom cleaners.

[0003] In addition, the effect of detergents is generally short-lived. Therefore, even if the scale is successfully removed using detergents, the scale will re-form. As a result, the detergents have to be used frequently, which is time-consuming.

[0004] Additionally, anti-scale agents that form a film on surfaces to which water adheres have also been developed (see, for example, Patent Document 1). The anti-scale agent of Patent Document 1 can prevent the adhesion of water stains without discoloring the target area.

[0005] However, the coating formed by such anti-scale agents is difficult to visually observe. It is also difficult to determine when the anti-scale agent's effectiveness has disappeared. Furthermore, when such anti-scale agents are applied by spraying, there is a risk of excessive use of the agent. In addition, unevenness is likely to occur depending on the target area, making the anti-scale agent's effectiveness uneven. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-13623 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a pressure-sensitive adhesive film that can provide an excellent effect of decomposing water stains, and also to provide a method for applying such a pressure-sensitive adhesive film. [Means for solving the problem]

[0008] Such objectives are as follows: (1) 13 This is achieved by the present invention described in (1) a substrate; A substrate; a pressure-sensitive adhesive layer provided on one surface of the substrate, The pressure-sensitive adhesive layer contains an organic acid that has the function of decomposing water stains attached to the adherend. fruit, The organic acid is unevenly distributed on the surface of the pressure-sensitive adhesive layer opposite to the substrate. An adhesive film characterized by: (2) a substrate; a pressure-sensitive adhesive layer provided on one surface of the substrate, the pressure-sensitive adhesive layer contains an organic acid having a function of decomposing water stains attached to an adherend, A pressure-sensitive adhesive film, wherein the contact angle of pure water with the surface of the pressure-sensitive adhesive layer is less than 120°. (3) a substrate made of a transparent material; a pressure-sensitive adhesive layer provided on one surface of the substrate, The pressure-sensitive adhesive film is characterized in that the pressure-sensitive adhesive layer contains an organic acid having the function of decomposing water stains attached to the adherend.

[0011] (4) The organic acid is uniformly dispersed in the adhesive layer. (2) or (3) The adhesive film according to claim 1.

[0012] (5) The organic acid is unevenly distributed on the surface of the pressure-sensitive adhesive layer opposite to the substrate. (2) or (3) The adhesive film according to claim 1.

[0017] ( 6 The substrate is made of a transparent material. or (2) The adhesive film according to claim 1. (7) The pressure-sensitive adhesive film according to (1) or (3), wherein the contact angle of pure water with the surface of the pressure-sensitive adhesive layer is less than 120°. (8) An adhesive film according to any one of (1) to (7) above, wherein the organic acid comprises at least one selected from the group consisting of citric acid, malic acid, tartaric acid, succinic acid, malonic acid, maleic acid, lactic acid, glutaric acid, gluconic acid and acetic acid. (9) The pressure-sensitive adhesive film according to any one of (1) to (8) above, wherein the acid dissociation constant of the organic acid is 1.8 PKa or more and 5.8 PKa or less. (10) The pressure-sensitive adhesive film according to any one of (1) to (9), wherein the content of the organic acid in the pressure-sensitive adhesive layer is 1% by mass or more and 50% by mass or less. (11) The pressure-sensitive adhesive film according to any one of (1) to (10) above, wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive. (12) The pressure-sensitive adhesive film according to any one of (1) to (11) above, wherein the pressure-sensitive adhesive layer is of a releasable type.

[0018] ( 13 ) The adhesive layer is provided on one side of the substrate and contains an organic acid that has the function of decomposing water stains attached to an adherend. providing an adhesive film; and adhering the surface of the pressure-sensitive adhesive layer to an adherend via a water film. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a pressure-sensitive adhesive film that has an excellent effect of decomposing water stains, and also to provide a method for applying such a pressure-sensitive adhesive film. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a longitudinal sectional view schematically showing a first embodiment of the pressure-sensitive adhesive film of the present invention. [Figure 2] FIG. 1 is a longitudinal cross-sectional view schematically illustrating an example of a method for using the pressure-sensitive adhesive film of the present invention. [Figure 3] FIG. 2 is a longitudinal sectional view schematically showing a second embodiment of the pressure-sensitive adhesive film of the present invention. [Figure 4] FIG. 3 is a longitudinal sectional view schematically showing a third embodiment of the pressure-sensitive adhesive film of the present invention. [Figure 5] FIG. 10 is a longitudinal sectional view schematically showing a fourth embodiment of the pressure-sensitive adhesive film of the present invention. [Figure 6] FIG. 10 is a perspective view schematically showing a fifth embodiment of the pressure-sensitive adhesive film of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, the adhesive film and adhesive film application method of the present invention will be described based on preferred embodiments shown in the accompanying drawings.

[0022] First Embodiment First, a first embodiment of the pressure-sensitive adhesive film of the present invention will be described.

[0023] (adhesive film) FIG. 1 is a longitudinal sectional view showing a first embodiment of the pressure-sensitive adhesive film of the present invention.

[0024] As shown in Figure 1, the adhesive film 1 has a substrate 11 and an adhesive layer 12 provided on a second surface 112, which is one surface of the substrate 11. The adhesive layer 12 also contains an organic acid 20 that has the function of decomposing water stains adhering to an adherend, such as a mirror glass or window glass. Such an adhesive film 1 is attached to an adherend so that the organic acid 20 contained in the adhesive layer 12 decomposes water stains adhering to the adherend.

[0025] (base material) The substrate 11 has a first surface 111 and a second surface 112 and has the function of supporting the pressure-sensitive adhesive layer 12 .

[0026] The substrate 11 may be in any form, such as a film, a woven fabric, a nonwoven fabric, paper, a porous body, etc. Among these, the substrate 11 is preferably in the form of a film. In this specification, the term "film" is used to include the concept of a sheet.

[0027] Furthermore, the substrate 11 may or may not have flexibility, but it is preferable that the substrate 11 has flexibility, which improves the workability of attaching the pressure-sensitive adhesive film 1 to the adherend.

[0028] The constituent material of the substrate 11 is not particularly limited, and examples thereof include resin materials, metal materials, and plant fibers such as pulp. Among these, resin materials are preferred, and films made of resin materials are particularly preferred. This allows for the production of a substrate 11 that is easy to work with and has excellent water resistance.

[0029] Examples of resin materials constituting the substrate 11 include polyolefins such as polyethylene, polypropylene, and ethylene-propylene copolymers; polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate; acetate resin, acrylonitrile-butadiene-styrene copolymer (ABS) resin, polystyrene, polyvinyl chloride, polyamide, polyesteramide, polyetherimide, polyetheretherketone, polyarylate, polyimide, polyamideimide, poly-p-phenylene sulfide, and polyetherester. These may be used alone or in combination of two or more as the resin material constituting the substrate 11.

[0030] Among these, the resin material constituting the substrate 11 is preferably a polyolefin such as polyethylene or polypropylene, and more preferably a polyester such as polyethylene terephthalate or polybutylene terephthalate.

[0031] This can improve the strength of the adhesive film 1 and can further improve the workability of attaching the adhesive film 1 to an adherend. It also makes it easier to wind up the adhesive film 1 into a roll.

[0032] The substrate 11 may also contain components other than the above-mentioned constituent materials. Examples of such components include colorants such as dyes and pigments, antioxidants such as anilides and phenols, ultraviolet absorbers such as benzophenones and benzotriazoles, light stabilizers, modifiers, rust inhibitors, fillers, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, antistatic agents, polymerization inhibitors, crosslinking agents, catalysts, plasticizers, leveling agents, thickeners, softeners, dispersants, and the like.

[0033] The substrate 11 may be a single layer or a laminate including multiple layers. The substrate 11 may be made of a gradient material whose composition changes gradually in the thickness direction, for example.

[0034] At least one of the first surface 111 and the second surface 112 of the substrate 11 may be subjected to a surface treatment. Examples of such surface treatments include a roughening treatment, a hydrophilization treatment, and a water-repellent treatment. For example, the first surface 111 of the substrate 11 may be subjected to a hydrophilization treatment as an anti-fogging treatment. When an adhesive film 1 including a hydrophilically treated substrate 11 is attached to a mirror glass or the like, an anti-fogging effect is obtained in the attachment area of ​​the mirror glass. Examples of hydrophilization treatments include a corona treatment, a plasma treatment, and the formation of a hydrophilic layer. Furthermore, for example, the second surface 112 of the substrate 11 may be subjected to a roughening treatment. This can improve the adhesion between the substrate 11 and the adhesive layer 12.

[0035] The thickness of the substrate 11 is not particularly limited, but is preferably 15 μm or more and 300 μm or less, and more preferably 20 μm or more and 75 μm or less. A substrate 11 having a thickness in this range is easy to handle and easy to visually inspect. Therefore, the pressure-sensitive adhesive film 1 can be easily attached to an adherend, and the state of adhesion of the pressure-sensitive adhesive film 1 can be easily visually inspected.

[0036] The substrate 11 may be substantially transparent or opaque, but is preferably substantially transparent. Substantially transparent means colorless and transparent, colored and transparent, or translucent. For example, when the adhesive film 1 is attached to a mirror glass, the substrate 11 is preferably colorless and transparent. This allows the organic acid 20 contained in the adhesive layer 12 to decompose water stains adhering to the mirror glass without interfering with the use of the mirror. The same effect can be obtained when the adhesive film 1 is attached to a window glass or the like.

[0037] (Adhesive layer) The pressure-sensitive adhesive layer 12 is the portion that comes into contact with or approaches the adherend when the pressure-sensitive adhesive film 1 is attached to the adherend. Specifically, the pressure-sensitive adhesive layer 12 has a first surface 121 that faces the substrate 11 and a second surface 122 that faces the adherend. The pressure-sensitive adhesive layer 12 also has the function of retaining or supporting the organic acid 20. That is, the pressure-sensitive adhesive layer 12 is composed of a pressure-sensitive adhesive layer-forming composition, and the pressure-sensitive adhesive layer-forming composition contains a pressure-sensitive adhesive and the organic acid 20.

[0038] Examples of adhesives constituting the adhesive layer 12 include thermoplastic resin-based adhesives, thermosetting resin-based adhesives, and elastomer-based adhesives. Specific examples include acrylic-based adhesives, polyvinyl alcohol (PVA)-based adhesives, polyvinyl ether-based adhesives, urethane-based adhesives, polyester-based adhesives, and silicone-based adhesives. Among these, from the viewpoint of weather resistance and the like, acrylic-based adhesives, urethane-based adhesives, and silicone-based adhesives are preferably used, and acrylic-based adhesives are more preferably used.

[0039] Specific examples of acrylic adhesives include copolymers of alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.

[0040] By using the above-mentioned adhesive, even if the adhesive layer 12 containing the organic acid 20 is formed, adverse effects such as excessive decrease in adhesive strength of the adhesive layer 12, excessive alteration, deterioration, or gas generation of the adhesive layer 12 do not occur. The above-mentioned adhesives can be used alone or in combination of two or more. The organic acid 20 is mixed into such an adhesive.

[0041] The organic acid 20 has the function of decomposing scale adhering to the adherend. In other words, the organic acid 20 exerts a scale decomposition effect. Scale is formed when tap water dries (evaporates). Therefore, scale contains calcium carbonate, an alkaline component, as its main component. Scale also contains other salts (e.g., magnesium bicarbonate) that are contained in the water before evaporation.

[0042] Examples of organic acids 20 include citric acid, malic acid (hydroxysuccinic acid), tartaric acid (dihydroxysuccinic acid), succinic acid (ethylene succinic acid), malonic acid, maleic acid, lactic acid, glutaric acid, gluconic acid, and acetic acid. These may be used alone or in combination of two or more. Among these, organic acids 20 having two or more carboxy groups are preferred, and those having both a carboxy group and a hydroxy group are more preferred.

[0043] Furthermore, the organic acid 20 is preferably a solid or liquid at room temperature, which makes it easy to mix the organic acid 20 with the adhesive and easily form the adhesive layer 12. When the organic acid 20 is a solid at room temperature, the organic acid 20 is preferably in the form of powder or granules.

[0044] The acid dissociation constant of organic acid 20 is preferably 1.8 PKa or more and 5.8 PKa or less, and more preferably 1.8 PKa or more and 4.8 PKa or less. Organic acid 20 having an acid dissociation constant within this range can more reliably decompose limescale attached to the adherend. Note that, with regard to the above range of the acid dissociation constant of organic acid 20, if organic acid 20 dissociates sequentially, the acid dissociation constant of the first stage shall apply.

[0045] The organic acid 20 is uniformly dispersed throughout the pressure-sensitive adhesive layer 12. That is, the organic acid 20 is uniformly dispersed in the planar and thickness directions of the pressure-sensitive adhesive layer 12. Therefore, the pressure-sensitive adhesive layer 12 can be easily obtained by mixing the pressure-sensitive adhesive and the organic acid 20 to obtain a composition for forming a pressure-sensitive adhesive layer, and then forming this into a layer.

[0046] Furthermore, the organic acid 20, being uniformly dispersed throughout the adhesive layer 12, can also achieve the following effect. That is, the organic acid 20 present on the second surface 122 side of the adhesive layer 12 primarily reacts with the alkaline components of limescale adhering to the adherend. As a result, the concentration of the organic acid 20 on the second surface 122 side of the adhesive layer 12 is lower than the concentration on the first surface 121 side of the adhesive layer 12. As a result, the organic acid 20 present on the first surface 121 side of the adhesive layer 12 migrates to the second surface 122 side. As a result, the limescale decomposition effect attributable to the organic acid 20 can be sustained. In this way, the adhesive film 1 can sustainably decompose limescale. Such an adhesive film 1 is suitable, for example, for applications in which the adhesive film 1 is attached to an adherend and the adherend is used, such as for mirrors.

[0047] The content of organic acid 20 in pressure-sensitive adhesive layer 12 is preferably 1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 35% by mass or less. By including organic acid 20 in pressure-sensitive adhesive layer 12 at a content within this range, the adhesive strength of pressure-sensitive adhesive layer 12 can be maintained at an appropriate level, while the scale-decomposing effect of organic acid 20 can be effectively exerted.

[0048] Furthermore, in order to emphasize the immediate effect of the organic acid 20 in decomposing water stains, the content of the organic acid 20 may be 30 parts by mass or more and 50 parts by mass or less per 100 parts by mass of the adhesive (converted to solid content).

[0049] The pressure-sensitive adhesive layer 12 is preferably removable. This prevents adhesive residue on the adherend surface when the pressure-sensitive adhesive film 1 is peeled off, as described below. The removable pressure-sensitive adhesive layer 12 can be obtained by appropriately determining conditions such as the composition and content of the pressure-sensitive adhesive, and the composition and content of the organic acid 20. Note that by mixing the organic acid 20 with the pressure-sensitive adhesive, the adhesive strength of the pressure-sensitive adhesive can be reduced. Therefore, the removable pressure-sensitive adhesive layer 12 can also be obtained by adjusting the content of the organic acid 20 so as to appropriately reduce the adhesive strength of the pressure-sensitive adhesive layer 12.

[0050] The adhesive layer 12 may contain an adhesive and an organic acid 20, and may also contain other components. For example, the adhesive layer 12 may contain a second scale decomposer in addition to the organic acid 20 (first scale decomposer). The second scale decomposer preferably has an acid dissociation constant within the aforementioned range of the acid dissociation constant of the organic acid 20 (1.8 PKa or more and 5.8 PKa or less). An example of such a second scale decomposer is acrylic acid. This acrylic acid is contained, for example, in the form of being copolymerized in an acrylic acid ester copolymer of an acrylic adhesive. By containing the organic acid 20 (first scale decomposer) and the acrylic acid (second scale decomposer), the adhesive layer 12 can improve its cohesive strength and adhesive strength and complement the scale decomposition effect of the organic acid 20. In other words, the synergistic effect of the organic acid 20 and the acrylic acid described above can more effectively decompose scale.

[0051] From the viewpoint of exerting such a synergistic effect, the content of the second scale decomposer in the pressure-sensitive adhesive layer 12 is preferably 0.1% by mass or more and 30% by mass or less, and more preferably 0.3% by mass or more and 10% by mass or less. Note that when the content of the first scale decomposer in the pressure-sensitive adhesive layer 12 is X and the content of the second scale decomposer in the pressure-sensitive adhesive layer 12 is Y, the second scale decomposer may be contained in the pressure-sensitive adhesive layer 12 so as to satisfy the relationship X>Y, or the second scale decomposer may be present in the pressure-sensitive adhesive layer 12 so as to satisfy the relationship X≦Y, but it is preferable that the second scale decomposer be contained in the pressure-sensitive adhesive layer 12 so as to satisfy the relationship X>Y. This makes it possible to reliably exert the above-mentioned synergistic effect.

[0052] Examples of other components include crosslinkers, tackifiers, fillers, antioxidants, softeners, ultraviolet absorbers, light stabilizers, colorants, modifiers, rust inhibitors, flame retardants, hydrolysis inhibitors, surface lubricants, corrosion inhibitors, heat stabilizers, lubricants, primers, antistatic agents, polymerization inhibitors, catalysts, leveling agents, thickeners, dispersants, and antifoaming agents.

[0053] Examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, metal chelate-based crosslinking agents, amine-based crosslinking agents, and amino resin-based crosslinking agents, and one or more selected from these may be used in combination.

[0054] Examples of tackifiers include rosin resins, terpene phenol resins, terpene resins, aromatic hydrocarbon-modified terpene resins, petroleum resins, coumarone-indene resins, styrene resins, phenol resins, and xylene resins.

[0055] Examples of fillers include zinc oxide, titanium oxide, silica, calcium carbonate, and barium sulfate.

[0056] Examples of the softener include process oil, liquid rubber, and plasticizer. Examples of the antioxidant include anilide-based antioxidants, phenol-based antioxidants, and thioester-based antioxidants.

[0057] For example, when an emulsion-type acrylic adhesive is used as the adhesive, the adhesive layer 12 can be formed by the following method. First, an organic acid 20 is added to an acrylic adhesive in an aqueous solvent, and the two are mixed to obtain a composition for forming an adhesive layer (coating liquid). The coating liquid is applied to the second surface 112 of the substrate 11 to form a coating film. The coating film is dried to form the adhesive layer 12. Examples of methods for applying the coating liquid include roll coating, gravure coating, reverse coating, spray coating, knife coating, die coating, and bar coating.

[0058] Alternatively, the pressure-sensitive adhesive layer 12 may be formed by extrusion molding, followed by bonding to the substrate 11.

[0059] The thickness of the adhesive layer 12 is not particularly limited, but is preferably from 5 μm to 100 μm, and more preferably from 10 μm to 60 μm. The adhesive layer 12 having a thickness in this range provides necessary and sufficient adhesive strength and also supports a sufficient amount of the organic acid 20.

[0060] Furthermore, the contact angle of pure water with second surface 122, which is the surface of pressure-sensitive adhesive layer 12, is preferably less than 120°. Specifically, the contact angle of pure water with second surface 122 of pressure-sensitive adhesive layer 12 is preferably 10° or more and less than 90°, and more preferably 20° or more and 70° or less. The contact angle can be measured, for example, in accordance with JIS R 3257:1999.

[0061] As a result, as will be described later, when the pressure-sensitive adhesive film 1 is attached to an adherend via water, the water is more likely to wet and spread in the planar direction of the second surface 122 of the pressure-sensitive adhesive layer 12. This allows water to be distributed uniformly between the second surface 122 of the pressure-sensitive adhesive layer 12 and the adherend surface. As a result, the pressure-sensitive adhesive layer 12 can exert a water stain decomposition effect and a water stain removal effect evenly in the planar direction. Furthermore, the pressure-sensitive adhesive layer 12 can be easily attached to the adherend.

[0062] The pressure-sensitive adhesive layer 12 as described above may be attached to the adherend via water or may be attached directly to the adherend, but is preferably attached to the adherend via water.

[0063] (How to apply adhesive film) Next, an example of a method for adhering the pressure-sensitive adhesive film of the present invention will be described. FIG. 2 is a vertical cross-sectional view showing an example of a method of using the pressure-sensitive adhesive film of the present invention.

[0064] 2 shows a glass plate 100 as the adherend. White water stains (not shown) are attached to the surface of the glass plate 100 (the surface on the adhesive film 1 side). In addition, a mirror surface (not shown) is provided on the surface of the glass plate 100 opposite the adhesive film 1.

[0065] The adherend is not particularly limited as long as it can hold water, and examples of the adherend include walls of bathrooms, shower rooms, kitchens, washrooms, toilets, swimming pools, bathing facilities, etc., window glass, mirror glass, metal mirrors such as aluminum mirrors and stainless steel mirrors, resin mirrors such as acrylic mirrors, and other items used around water.

[0066] Water is applied to the surface of the glass plate 100 having such water stains. The method for applying water in this manner is not particularly limited, and examples include applying water to the surface of the glass plate 100 by showering or spraying, or contacting the surface with a cloth containing water.

[0067] Next, the adhesive film 1 is attached to the glass plate 100 so that the surface of the glass plate 100 with water adhering thereto faces the second surface 122 of the adhesive layer 12. This operation is performed so that the water spreads in the planar direction between the surface of the glass plate 100 and the second surface 122 of the adhesive layer 12, without leaving any air bubbles. Specifically, after one end of the adhesive film 1 is positioned against the surface of the glass plate 100, the adhesive film 1 is attached to the surface of the glass plate 100 while gradually pressing from its center to the other end. In this way, the adhesive film 1 is attached to the glass plate 100 via the water film 30 (see FIG. 2). In the adhesive film 1 shown in FIG. 2, the adhesive layer 12 is in close contact with the surface of the glass plate 100 via the water film 30. In this attached state, the adhesive film 1 can exhibit the effect of making water stains less noticeable due to its light reflection effect.

[0068] The method for forming the water film 30 may be the opposite to the above, that is, by adhering water to the second surface 122 of the pressure-sensitive adhesive layer 12. Furthermore, the water film 30 may be formed by adhering water to both the surface of the glass plate 100 and the second surface 122 of the pressure-sensitive adhesive layer 12. That is, before the pressure-sensitive adhesive film 1 is attached to the glass plate 100, the water film 30 may be formed by adhering water to at least one of the surface of the glass plate 100 and the second surface 122 of the pressure-sensitive adhesive layer 12 (the surface opposite to the substrate 11).

[0069] In the adhered state, the organic acid 20 provided in the adhesive layer 12 reacts mainly with the alkaline components of the water stains attached to the surface of the glass plate 100, thereby decomposing the water stains. As a result, the white color of the water stains is reduced or eliminated.

[0070] The adhesion period of the PSA film 1 may be adjusted as appropriate depending on the intended use of the PSA film 1. This adhesion period can be, for example, from several hours to several months. For example, in applications where the organic acid 20 is required to have an immediate effect in decomposing limescale, the adhesion period can be several hours. In this case, it is preferable to use a PSA film 1 in which the immediate effect of the organic acid 20 in decomposing limescale is promoted by, for example, increasing the content of organic acid 20.

[0071] The PSA film 1 can be used while remaining attached to the glass plate 100 even after the reaction between the organic acid 20 and the scale has ceased. That is, after the PSA film 1 exerts a scale-decomposing effect on the surface of the glass plate 100, it can have the effect of preventing scale from re-adhering to the surface of the glass plate 100. For example, the PSA film 1 can be used while attached to an adherend until scale is formed on the first surface 111 of the substrate 11 of the PSA film 1.

[0072] Finally, the adhesive film 1 is peeled off from the glass plate 100. At this time, at least a portion of the insoluble components of the decomposed limescale are removed while remaining attached to the adhesive layer 12. Meanwhile, the soluble components of the decomposed limescale can be washed away with water or the like. In this way, the adhesive film 1 can be used to remove limescale formed on the adherend, the glass plate 100.

[0073] As described above, the PSA film 1 can decompose and remove limescale, and also prevent limescale buildup. Therefore, it can be said that the PSA film 1 can achieve an excellent limescale cleaning effect while reducing the frequency of use.

[0074] The method for adhering an adhesive film of the present invention includes the steps of preparing an adhesive film 1 and adhering the surface (second surface 122) of the adhesive layer 12 of the adhesive film 1 to an adherend via a water film 30. This allows the adhesive film 1 to be adhered uniformly and properly. As a result, the above-mentioned effects of the adhesive film 1 are effectively exhibited.

[0075] Furthermore, in the PSA film 1, the organic acid 20 is uniformly dispersed throughout the entire PSA layer 12. In other words, the organic acid 20 is provided in the PSA layer 12 so that it is present in a constant amount relative to the adherend surface. This prevents the organic acid 20 from being supplied to the surface of the adherend in excessive amounts. Therefore, the PSA film 1 makes it possible to provide a component that breaks down water stains uniformly on the adherend surface.

[0076] Second Embodiment Next, a second embodiment of the pressure-sensitive adhesive film of the present invention will be described. FIG. 3 is a longitudinal sectional view showing a second embodiment of the pressure-sensitive adhesive film of the present invention.

[0077] The adhesive film 1 of the second embodiment will be described below, focusing on the differences from the adhesive film 1 of the first embodiment, and a description of similar points will be omitted.

[0078] The adhesive film 1 of the second embodiment is similar to the adhesive film 1 of the first embodiment except for the configuration of the adhesive layer 12. That is, in the adhesive film 1 of the second embodiment, the organic acid 20 is unevenly distributed on the second surface 122 side of the adhesive layer 12. In other words, the adhesive layer 12 contains the organic acid 20 such that the concentration distribution (distribution density) of the organic acid 20 varies in the thickness direction of the adhesive layer 12.

[0079] With such an adhesive film 1, the organic acid 20 can be provided at a high concentration (high density) on the second surface 122 side of the adhesive layer 12, compared to when the organic acid 20 is uniformly dispersed in the adhesive layer 12 as in the first embodiment, and the organic acid 20 has an immediate effect in decomposing scale.

[0080] Furthermore, such an adhesive film 1 also makes it possible to achieve the aforementioned effect, that is, to continuously decompose water stains.

[0081] <Third embodiment> Next, a third embodiment of the pressure-sensitive adhesive film of the present invention will be described. FIG. 4 is a schematic longitudinal sectional view showing a third embodiment of the pressure-sensitive adhesive film of the present invention.

[0082] The following description of the adhesive film 1 of the third embodiment will focus on the differences from the adhesive film 1 of the first embodiment, and a description of similar points will be omitted.

[0083] The adhesive film 1 of the third embodiment is similar to the adhesive film 1 of the first embodiment except for the configuration of the adhesive layer 12. That is, in the adhesive film 1 of the third embodiment, the adhesive layer 12 has a two-layer structure composed of an adhesive layer 12A that does not contain organic acid 20 and an adhesive layer 12B that contains organic acid 20. Even in this configuration, it can be said that the organic acid 20 is unevenly distributed on the surface of the adhesive layer 12 opposite the substrate 11.

[0084] Such an adhesive film 1 can easily form an adhesive layer 12 having a different concentration distribution of the organic acid 20 in the thickness direction. For example, an adhesive layer-forming composition for the adhesive layer 12A and an adhesive layer-forming composition for the adhesive layer 12B can be prepared and applied sequentially to the second surface 112 of the substrate 11 using the coating method described above to form an adhesive layer 12 having a two-layer structure. Such an adhesive film 1 can also achieve the effect described above, i.e., the ability to continuously decompose water stains. At least one of the adhesive layer 12A and the adhesive layer 12B may contain acrylic acid as a second water stain decomposing agent.

[0085] In addition, the pressure-sensitive adhesive layer 12A may contain the organic acid 20. That is, the two-layer structure (multilayer structure) of the pressure-sensitive adhesive layer 12 may have different concentrations of the organic acid 20. For example, the concentration of the organic acid 20 in the pressure-sensitive adhesive layer 12A may be C A The concentration of the organic acid 20 in the adhesive layer 12B is C B In this case, 0≦C A <C B The pressure-sensitive adhesive layer 12 may be configured to satisfy the following relationship. With this configuration, the organic acid 20 can be provided at a higher concentration (higher density) on the surface (second surface 122) side of the pressure-sensitive adhesive layer 12 than when the organic acid 20 is uniformly dispersed in the pressure-sensitive adhesive layer 12 as in the first embodiment. As a result, the immediate effect of the organic acid 20 in decomposing water stains can be promoted. This effect can be more significantly exhibited when the pressure-sensitive adhesive layer 12B contains acrylic acid.

[0086] Conversely, 0≦C B <C A The pressure-sensitive adhesive layer 12 may be configured so as to satisfy the following relationship. With such a configuration, the organic acid 20 gradually migrates to the surface side of the pressure-sensitive adhesive layer 12, making it possible to continuously decompose water stains.

[0087] Furthermore, the two-layer structure (multilayer structure) of the pressure-sensitive adhesive layer 12 may contain different types of organic acid 20. For example, the pressure-sensitive adhesive layer 12A may contain the organic acid 20 such that the acid dissociation constant of the organic acid 20 contained in the pressure-sensitive adhesive layer 12A is lower than the acid dissociation constant of the organic acid 20 contained in the pressure-sensitive adhesive layer 12B. In other words, the pressure-sensitive adhesive layer 12A may contain an organic acid 20 that has a stronger water scale decomposition effect than the pressure-sensitive adhesive layer 12B. As a result, after the organic acid 20 contained in the pressure-sensitive adhesive layer 12B reacts, the organic acid 20 contained in the pressure-sensitive adhesive layer 12A that has a stronger water scale decomposition effect may migrate to the pressure-sensitive adhesive layer 12B and additionally decompose water scale. In this case, when the pressure-sensitive adhesive layer 12A further contains acrylic acid, the effect of additionally decomposing water scale is more pronounced. On the other hand, the pressure-sensitive adhesive layer 12B may contain an organic acid 20 that has a stronger water scale decomposition effect than the pressure-sensitive adhesive layer 12A. This promotes the immediate effect of decomposing water scale of organic acid 20. In this case, by further including acrylic acid in pressure-sensitive adhesive layer 12B, the immediate effect of decomposing water scale of organic acid 20 can be further promoted.

[0088] <Fourth embodiment> Next, a fourth embodiment of the pressure-sensitive adhesive film of the present invention will be described. FIG. 5 is a vertical cross-sectional view showing a fourth embodiment of the pressure-sensitive adhesive film of the present invention.

[0089] The adhesive film 1 of the fourth embodiment will be described below, focusing on the differences from the adhesive film 1 of the first embodiment, and a description of similar points will be omitted.

[0090] The adhesive film 1 of the fourth embodiment further includes a release liner 13, but is otherwise similar to the adhesive film 1 of the first embodiment. Specifically, in the adhesive film 1 of the fourth embodiment, a release liner 13 is further provided on the second surface 122 of the adhesive layer 12. The adhesive film 1 of this embodiment may be produced by forming the adhesive layer 12 on the release liner 13, and then bonding the first surface 121 of the adhesive layer 12 to the substrate 11.

[0091] Release liner 13 has the function of protecting pressure-sensitive adhesive layer 12 (for example, preventing the adhesion of dust). Release liner 13 is peeled off when adhesive film 1 is attached to an adherend. The material constituting release liner 13 is not particularly limited, and for example, polyester, polypropylene, etc. can be used.

[0092] According to such an adhesive film 1, the adhesive film 1 can be stored and transported in sheet form. This makes the adhesive film 1 easy to handle. It goes without saying that such an adhesive film 1 can also achieve the effects described above. The adhesive films 1 of the second and third embodiments may have a release liner 13.

[0093] Fifth Embodiment Next, a fifth embodiment of the pressure-sensitive adhesive film of the present invention will be described. FIG. 6 is a schematic perspective view showing a fifth embodiment of the pressure-sensitive adhesive film of the present invention.

[0094] The following description of the adhesive film 1 of the fifth embodiment will focus on the differences from the adhesive film 1 of the first embodiment, and a description of similar points will be omitted.

[0095] The adhesive film 1 of the fifth embodiment is similar to the adhesive film 1 of the first embodiment, except for the configuration of the substrate 11. That is, the first surface 111 of the substrate 11 is subjected to a release treatment that is effective for the adhesive layer 12. In other words, in this embodiment, the substrate 11 has releasability. This makes it possible to prevent poor release between the second surface 122 of the adhesive layer 12 and the first surface 111 of the substrate 11.

[0096] With such an adhesive film 1, the substrate 11 also functions as a release liner, so it can be said that the adhesive film 1 can be stored and transported in a rolled state without a release liner. Furthermore, with such an adhesive film 1, the adhesive film 1 can be unwound from the rolled state and cut to the required amount for use. For this reason, it can be said that such an adhesive film 1 has high conformability to the shape and area of ​​the adhesion region of the adherend. Needless to say, such an adhesive film 1 can also exhibit the effects described above.

[0097] Furthermore, the release treatment of the first surface 111 of the substrate 11 is not particularly limited as long as it can avoid the problem of the adhesive layer 12 sticking to the substrate 11 and not peeling off when the adhesive film 1 is wound into a roll. For example, a release agent layer may be provided on the first surface 111 of the substrate 11.

[0098] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these.

[0099] For example, the pressure-sensitive adhesive film according to the present invention may have at least one intermediate layer between the substrate and the pressure-sensitive adhesive layer.

[0100] The pressure-sensitive adhesive film according to the present invention may also have at least one coating layer on the surface (first surface) of the substrate opposite the surface facing the pressure-sensitive adhesive layer. For example, a printed layer may be provided on the first surface of the substrate. Alternatively, a coating layer may be provided on the surface of the pressure-sensitive adhesive layer opposite the substrate (the surface of the pressure-sensitive adhesive film). This can prevent unexpected contact between the organic acid and water on the surface of the pressure-sensitive adhesive film before the pressure-sensitive adhesive film is attached. [Explanation of symbols]

[0101] 1...Adhesive film 11...Base material 111...first surface of substrate 112...second surface of substrate 12...Adhesive layer 12A...Adhesive layer 12B...Adhesive layer 121...First surface of adhesive layer 122...Second surface of adhesive layer 13...Release liner 20...Organic acid 30…Water film 100...glass plate

Claims

1. A substrate; a pressure-sensitive adhesive layer provided on one surface of the substrate, the pressure-sensitive adhesive layer contains an organic acid having a function of decomposing water stains attached to an adherend, A pressure-sensitive adhesive film, characterized in that the organic acid is unevenly distributed on the surface of the pressure-sensitive adhesive layer opposite to the substrate.

2. A substrate; a pressure-sensitive adhesive layer provided on one surface of the substrate, the pressure-sensitive adhesive layer contains an organic acid having a function of decomposing water stains attached to an adherend, A pressure-sensitive adhesive film, wherein the contact angle of pure water with the surface of the pressure-sensitive adhesive layer is less than 120°.

3. A substrate made of a transparent material; a pressure-sensitive adhesive layer provided on one surface of the substrate, The pressure-sensitive adhesive film is characterized in that the pressure-sensitive adhesive layer contains an organic acid having the function of decomposing water stains attached to the adherend.

4. The pressure-sensitive adhesive film according to claim 2 or 3, wherein the organic acid is uniformly dispersed in the pressure-sensitive adhesive layer.

5. The pressure-sensitive adhesive film according to claim 2 or 3, wherein the organic acid is unevenly distributed on the surface of the pressure-sensitive adhesive layer opposite to the substrate.

6. The adhesive film according to claim 1 or 2, wherein the substrate is made of a transparent material.

7. The pressure-sensitive adhesive film according to claim 1 or 3, wherein the contact angle of pure water with the surface of the pressure-sensitive adhesive layer is less than 120°.

8. The adhesive film according to any one of claims 1 to 7, wherein the organic acid comprises at least one selected from the group consisting of citric acid, malic acid, tartaric acid, succinic acid, malonic acid, maleic acid, lactic acid, glutaric acid, gluconic acid, and acetic acid.

9. The pressure-sensitive adhesive film according to claim 1 , wherein the organic acid has an acid dissociation constant of 1.8 PKa or more and 5.8 PKa or less.

10. The pressure-sensitive adhesive film according to claim 1 , wherein the content of the organic acid in the pressure-sensitive adhesive layer is 1% by mass or more and 50% by mass or less.

11. The pressure-sensitive adhesive film according to claim 1 , wherein the pressure-sensitive adhesive layer contains an acrylic pressure-sensitive adhesive.

12. The pressure-sensitive adhesive film according to claim 1 , wherein the pressure-sensitive adhesive layer is a removable type.

13. A process of preparing a substrate and an adhesive film having an adhesive layer provided on one side of the substrate and containing an organic acid having the function of decomposing water stains attached to an adherend; and adhering the surface of the pressure-sensitive adhesive layer to an adherend via a water film.

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