Writing-feel improving sheet

Abstract

A writing-feel improving sheet 1 having a surface on which a touch pen is brought into contact, wherein the distance between the center of gravity point of the writing-feel improving sheet 1 and the reference center of gravity point is 4.8 or lower, said reference center of gravity point being obtained by performing principal component analysis using, as data: an arithmetic average roughness Ra (μm), a ten-point average roughness Rzjis (μm), and a rolling circle maximum height waviness (μm) of a writing surface of a writing object serving as a reference and the surface of the writing-feel improving sheet on which the touch pen is brought into contact; a coefficient of static friction and a coefficient of dynamic friction measured by bringing a writing tool serving as a reference into contact with the writing surface of the writing object serving as a reference, then applying a load of 200 g on the writing tool, and linearly sliding the writing tool at 16.6 m / second while maintaining the angle between the writing tool and the writing surface at 45; and a coefficient of static friction and a coefficient of dynamic friction measured by the same method as above for the writing-feel improving sheet. This writing-feel improving sheet 1 makes it possible to obtain a desired writing feel.

Description

Writing feel improvement sheet

[0001] The present invention relates to a sheet for improving writing feel.

[0002] In recent years, image display devices (touch panels) with position detection functions that combine display and input functions have become increasingly popular in various electronic devices. In addition to touch panels that allow input with fingers, some also allow input with a touch pen, which allows for more precise and accurate input than with a finger. However, the display module of a touch panel is typically hard. Therefore, the writing experience with a touch pen is not as good as the writing experience with a pencil on paper.

[0003] In order to solve the problem of the writing feel when using a touch pen on a touch panel, it has been considered to attach a film that improves the writing feel (hereinafter, sometimes referred to as a "writing feel improving film" or "writing feel improving sheet") to the outermost surface of the touch panel. For example, Patent Document 1 discloses an example of such a writing feel improving film, which includes a transparent substrate film and linear convex portions that form a mesh structure on at least one surface of the transparent substrate film, the mesh structure having a plurality of regularly arranged compartments, and the linear convex portions occupying 5 to 80% of the area of ​​the entire surface of the touch film.

[0004] JP 2015-054417 A

[0005] However, the invention disclosed in Patent Document 1 failed to provide the desired writing feel, as the pen tip felt catchy or overly slippery, and the sound and vibration produced when writing were not pleasant.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a writing feel improving sheet that can provide a desired writing feel.

[0007] In order to achieve the above object, first, the present invention provides a writing feel improving sheet having a surface that comes into contact with a touch pen, the writing feel improving sheet having the following characteristics: arithmetic mean roughness Ra (μm), ten-point mean roughness Rzjis (μm), and rolling circle maximum height waviness (μm) of the writing surface of a reference writing object; static friction coefficient and dynamic friction coefficient measured by bringing a reference writing tool into contact with the writing surface of the reference writing object, applying a load of 200 g to the writing tool, and linearly sliding the writing tool at a speed of 16.6 mm / sec while maintaining an angle of 45° between the writing tool and the writing surface; and arithmetic mean roughness R a (μm), ten-point average roughness Rzjis (μm), rolling circle maximum height waviness (μm); and the static friction coefficient and dynamic friction coefficient measured by contacting the tip of a specified touch pen with the surface of the writing feel improving sheet that the touch pen will come into contact with, then applying a load of 200 g to the touch pen and sliding the touch pen linearly at a speed of 16.6 mm / sec while maintaining the angle between the touch pen and the surface at 45°, and performing principal component analysis using the data to provide a writing feel improving sheet characterized in that the distance between the reference center of gravity obtained by principal component analysis and the center of gravity of the writing feel improving sheet is 4.8 or less (Invention 1).

[0008] In the above invention (Invention 1), a writing feel similar to that when writing on a reference writing object with a reference writing implement can be obtained, that is, a desired writing feel can be obtained.

[0009] In the above invention (Invention 1), it is preferable that the distance between the center of gravity of the writing feel improvement sheet and the reference center of gravity obtained by performing principal component analysis on data evaluating the sensory evaluation items of writing comfort, pitch, pleasantness of sound, smoothness, softness, slipperiness, vibration, smoothness, and lightness, each on a five-point scale, when writing is performed on the reference writing object using the reference writing instrument, and data evaluating the sensory evaluation items of writing comfort, pitch, pleasantness of sound, smoothness, softness, slipperiness, vibration, smoothness, and lightness, each on a five-point scale, when writing is performed on the writing feel improvement sheet using the specified touch pen, is 1.4 or less (Invention 2).

[0010] According to the writing feel improving sheet of the present invention, a desired writing feel can be obtained.

[0011] 1 is a cross-sectional view of a writing feel improving sheet according to one embodiment of the present invention.

[0012] Hereinafter, an embodiment of the present invention will be described. A writing feel improving sheet according to one embodiment of the present invention has a surface that comes into contact with a touch pen, and preferably has the following physical properties. Specifically, the arithmetic mean roughness Ra (μm), ten-point mean roughness Rzjis (μm), and rolling circle maximum height waviness (μm) of the writing surface of a reference writing object; the static friction coefficient and dynamic friction coefficient measured by bringing a reference writing tool into contact with the writing surface of the reference writing object, applying a load of 200 g to the writing tool, and linearly sliding the writing tool at a speed of 16.6 mm / s while maintaining an angle of 45° between the writing tool and the writing surface; ... Average roughness Ra (μm), ten-point average roughness Rzjis (μm), rolling circle maximum height waviness (μm); and the static friction coefficient and dynamic friction coefficient measured by contacting the tip of a specified touch pen with the surface of the writing experience improving sheet that the touch pen comes into contact with, applying a load of 200 g to the touch pen, and linearly sliding the touch pen at a speed of 16.6 mm / s while maintaining the angle between the touch pen and the surface at 45°, are used as data for principal component analysis to obtain the center of gravity of the reference writing object / writing implement (reference center of gravity) and the center of gravity of the writing experience improving sheet. The writing experience improving sheet according to this embodiment preferably has a distance (physical property center of gravity distance) of 4.8 or less between the reference center of gravity obtained above and the center of gravity of the writing experience improving sheet. The details of the methods for measuring the arithmetic mean roughness Ra, the ten-point mean roughness Rzjis, and the maximum rolling circle height waviness in this specification are as described in the test examples below.

[0013] The reference writing object (reference writing object) is generally paper, and various types of paper can be selected as the reference writing object. In this embodiment, as an example, loose-leaf paper may be selected as the reference writing object. Other reference writing objects include, but are not limited to, blackboards, whiteboards, etc. The reference writing instrument (reference writing instrument) is also not limited to, and examples include pencils (HB, B, 2B, etc.), ballpoint pens (oil-based, water-based, gel, emulsion, etc.), fountain pens, felt-tip pens (oil-based, water-based, etc.), glass pens, writing brushes, brush pens, chalk, crayons, and mechanical pencils (HB, B, 2B, etc.). In this embodiment, as an example, a 2B pencil may be selected as the reference writing instrument.

[0014] The specified touch pen is not particularly limited, and conventionally known touch pens can be used. For example, touch pens having a polyacetal tip, a hard felt tip, an elastomer tip, or the like can be used. The shape (cross-sectional shape) of the touch pen tip is also not particularly limited, and can be appropriately selected from disk-shaped, circular, polygonal, and the like, but from the viewpoint of ease of obtaining the above physical properties, a circular shape is preferred. When the shape of the touch pen tip is circular, the diameter of the tip is preferably 0.1 to 5 mm, particularly preferably 0.2 to 2 mm, and even more preferably 0.3 to 1 mm.

[0015] The writing feel improving sheet according to this embodiment has the above-mentioned physical properties (distance between physical property centers of gravity), thereby providing a writing feel similar to that obtained when writing on a reference writing object with a reference writing instrument, i.e., a desired writing feel. For example, if a 2B pencil is selected as the reference writing instrument and loose-leaf paper is selected as the reference writing object, the writing feel improving sheet according to this embodiment provides a writing feel similar to that obtained when writing on loose-leaf paper with a 2B pencil. This is thought to be because the center of gravity obtained by performing principal component analysis on a given writing instrument and writing object using the arithmetic mean roughness Ra, ten-point mean roughness Rzjis, maximum rolling circle height waviness, static friction coefficient, and kinetic friction coefficient as data accurately represents the writing feel obtained from those writing instruments and writing objects.

[0016] From the above viewpoints, the distance between the physical center of gravity is preferably 4.800 or less, more preferably 4.400 or less, particularly preferably 4.000 or less, and even more preferably 3.600 or less. The lower limit of the distance between the physical center of gravity is most preferably 0, but is substantially preferably 0.100 or more, more preferably 0.500 or more, and particularly preferably 1.00 or more.

[0017] Here, principal component analysis is a statistical analysis method that aggregates data with many variables to create principal components. In this embodiment, data on the arithmetic mean roughness Ra, ten-point mean roughness Rzjis, rolling circle maximum height waviness, static friction coefficient, and dynamic friction coefficient are aggregated into the first principal component and the second principal component, and can be displayed on a two-dimensional graph with the first principal component on the horizontal axis and the second principal component on the vertical axis. Each principal component can be expressed by the following formula: Principal component = k １ x １ +k ２ x ２ +k ３ x ４ +k ４ x ４ +k ５ x ５ x １ = arithmetic mean roughness Ra k １ = x １ Weight (influence) x ２= Ten-point average roughness Rzjis k ２ = x ２ Weight (influence) x ３ = Maximum rolling circle height waviness k ３ = x ３ Weight (influence) x ４ = coefficient of static friction k ４ = x ４ Weight (influence) x ５ = Coefficient of dynamic friction k ５ = x ５ The weight (degree of influence) of each data item is automatically calculated based on the principles of principal component analysis when principal component analysis is performed.

[0018] When performing the principal component analysis, it is preferable to perform preprocessing. Specifically, scaling (standardization) is performed by subtracting the average value from each data value and then dividing by the standard deviation. It is preferable to perform principal component analysis using the scaled data. This allows the distance between the center of gravity of the reference and the center of gravity of the writing feel improvement sheet to be expressed as an absolute value.

[0019] The writing feel improving sheet according to one embodiment of the present invention preferably has the following physical properties: Specifically, principal component analysis is performed on data obtained by evaluating, on a five-point scale (1 to 5) the sensory evaluation items of writing comfort, pitch, pleasantness of sound, smoothness, softness, slipperiness, vibration, smoothness, and lightness when a reference writing implement is used to write on a reference writing object, and data obtained by evaluating, on a five-point scale (1 to 5) the sensory evaluation items of writing comfort, pitch, pleasantness of sound, smoothness, softness, slipperiness, vibration, smoothness, and lightness when a specific touch pen is used to write on a writing feel improving sheet (the writing feel improving sheet according to this embodiment and preferably multiple other writing feel improving sheets), to obtain the center of gravity (reference center of gravity) of the reference writing object / writing implement and the center of gravity of the writing feel improving sheet. In the writing feel improvement sheet according to this embodiment, it is preferable that the distance between the reference center of gravity obtained above and the center of gravity of the writing feel improvement sheet (sensory evaluation center of gravity distance) is 1.4 or less.

[0020] The sensory evaluation items are evaluated on a five-point scale (1 to 5) as follows, with the writing feel when writing with a reference writing instrument on a reference writing object being assigned a rating of "3." The "writing comfort" is evaluated as a value closer to 1 if the writing comfort is perceived to be worse than that of the reference writing instrument / writing object, and a value closer to 5 if the writing comfort is perceived to be better than that of the reference writing instrument / writing object. The "sound pitch" is evaluated as a value closer to 1 if the sound is perceived to be lower than that of the reference writing instrument / writing object, and a value closer to 5 if the sound is perceived to be higher than that of the reference writing instrument / writing object. The "sound pleasantness" is evaluated as a value closer to 1 if the sound is perceived to be less pleasant (more harsh) than that of the reference writing instrument / writing object, and a value closer to 5 if the sound is perceived to be more pleasant than that of the reference writing instrument / writing object. The "smoothness" is evaluated as a value closer to 1 if the sound is perceived to be more uneven than that of the reference writing instrument / writing object, and a value closer to 5 if the sound is perceived to be more smooth than that of the reference writing instrument / writing object. The closer to 1 the "softness" is perceived as harder than the reference writing instrument / writing object, and the closer to 5 the closer to softer it is perceived than the reference writing instrument / writing object. The closer to 1 the "slipperiness" is perceived as grippier than the reference writing instrument / writing object, and the closer to 5 the closer to 5 the closer to smoother it is perceived than the reference writing instrument / writing object. The closer to 1 the "vibration" is perceived as rougher than the reference writing instrument / writing object, and the closer to 5 the closer to smoother it is perceived than the reference writing instrument / writing object. The closer to 1 the "smoothness" is perceived as firmer than the reference writing instrument / writing object, and the closer to 5 the closer to smoother it is perceived than the reference writing instrument / writing object. The "lightness" is a value closer to 1 if the writing feel is heavier than the reference writing implement / writing object, and a value closer to 5 if the writing feel is lighter than the reference writing implement / writing object.

[0021] The writing feel improving sheet according to this embodiment, by having the above-mentioned physical property (distance between the centers of gravity of sensory evaluation), can provide a writing feel similar to that when writing on a reference writing object with a reference writing instrument, i.e., a desired writing feel can be obtained. For example, if a 2B pencil is selected as the reference writing instrument and loose-leaf paper is selected as the reference writing object, the writing feel improving sheet according to this embodiment can provide a writing feel similar to that when writing on loose-leaf paper with a 2B pencil. This is thought to be because the center of gravity obtained by performing principal component analysis on a given writing instrument and writing object using data on writing comfort, pitch, pleasant sound, smoothness, softness, slipperiness, vibration, smoothness, and lightness accurately represents the writing feel obtained from those writing instruments and writing objects.

[0022] From the above viewpoints, the sensory evaluation center-of-gravity distance is preferably 1.400 or less, more preferably 1.200 or less, particularly preferably 1.000 or less, and even more preferably 0.900 or less. The lower limit of the sensory evaluation center-of-gravity distance is most preferably 0, but is substantially preferably 0.100 or more, more preferably 0.300 or more, and particularly preferably 0.500 or more.

[0023] The principal component analysis for obtaining the sensory evaluation centroid distance can be performed in the same manner as the principal component analysis for obtaining the physical property centroid distance. It is preferable to aggregate each piece of data into the first principal component and the second principal component, and it is also preferable to perform preprocessing similar to that of the principal component analysis for obtaining the physical property centroid distance.

[0024] The writing feel improving sheet according to the present embodiment preferably satisfies either the physical property distance between the centers of gravity or the sensory evaluation distance between the centers of gravity, but more preferably satisfies both. Hereinafter, the "physical property distance between the centers of gravity" and the "sensory evaluation distance between the centers of gravity" may be collectively referred to as the "distance between the centers of gravity."

[0025] The arithmetic mean roughness Ra of the surface of the writing feel improving sheet according to this embodiment that comes into contact with the touch pen is preferably 0.1 to 10 μm, more preferably 0.3 to 5 μm, particularly preferably 0.5 to 2 μm, even more preferably 0.6 to 1.2 μm, and of these, preferably 0.7 to 0.9 μm. This makes it easier to satisfy the above-mentioned physical property (distance between centers of gravity).

[0026] The ten-point average roughness Rzjis of the surface of the writing feel improving sheet according to this embodiment that comes into contact with the touch pen is preferably 0.1 to 20 μm, more preferably 0.5 to 16 μm, particularly preferably 1 to 12 μm, even more preferably 3 to 10 μm, and most preferably 5 to 8 μm. This makes it easier to satisfy the above-mentioned physical property (distance between centers of gravity).

[0027] The maximum rolling circle height waviness of the surface of the writing feel improving sheet according to this embodiment that comes into contact with the touch pen is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, particularly preferably 1 to 10 μm, even more preferably 1.5 to 7 μm, and most preferably 2 to 4 μm. This makes it easier to satisfy the above-mentioned physical property (distance between centers of gravity).

[0028] The coefficient of dynamic friction of the surface of the writing feel improving sheet according to this embodiment that comes into contact with the touch pen is preferably 0.10 to 1.50, more preferably 0.12 to 1.20, particularly preferably 0.14 to 0.80, even more preferably 0.16 to 0.50, and most preferably 0.18 to 0.30. This makes it easier to satisfy the aforementioned physical property (distance between centers of gravity).

[0029] The static friction coefficient of the surface of the writing feel improving sheet according to this embodiment that comes into contact with the touch pen is preferably 0.10 to 1.50, more preferably 0.15 to 1.20, particularly preferably 0.20 to 0.80, even more preferably 0.24 to 0.60, and most preferably 0.28 to 0.40. This makes it easier to satisfy the physical property (distance between centers of gravity) described above.

[0030] The contact angle of oleic acid (oleic acid contact angle) of the surface of the writing feel improving sheet according to this embodiment that comes into contact with the touch pen is preferably 10° to 120°, more preferably 30° to 100°, particularly preferably 45° to 90°, even more preferably 55° to 80°, and most preferably 60° to 70°. This makes it easier to satisfy the physical property (distance between centers of gravity) described above. Note that the oleic acid contact angle in this specification refers to the angle on the side including the droplet, of the angle formed between the tangent to the droplet at the contact portion of the surface with the touch pen when the droplet is left standing on the surface that comes into contact with the touch pen. The same applies to the water contact angle described below.

[0031] The contact angle of the surface of the writing feel improving sheet according to this embodiment that comes into contact with a touch pen with water (water contact angle) is preferably 40° to 150°, more preferably 60° to 120°, particularly preferably 80° to 115°, even more preferably 90° to 110°, and most preferably 98° to 105°. This makes it easier to satisfy the aforementioned physical property (distance between centers of gravity). Detailed methods for measuring the oleic acid contact angle and water contact angle are as shown in the test examples described below.

[0032] The surface free energy of the surface of the writing feel improving sheet according to this embodiment that comes into contact with the touch pen is 1 to 60 mJ / m ２ is preferably 4 to 50 mJ / m ２ More preferably, it is 8 to 40 mJ / m ２ It is preferable that the irradiance is 12 to 30 mJ / m ２ It is preferable that the２ This makes it easier to satisfy the above-mentioned physical property (distance between centers of gravity). The method for measuring the surface free energy is as shown in the test examples described later.

[0033] The haze value of the writing feel improving sheet according to this embodiment is preferably 0 to 50%, more preferably 4 to 40%, particularly preferably 10 to 36%, even more preferably 16 to 32%, and most preferably 22 to 28%. This makes it easier to satisfy the above-mentioned physical properties and makes it suitable for optical applications. The haze value in this specification is a value measured in accordance with JIS K7136:2000.

[0034] The writing feel improving sheet according to this embodiment preferably includes a substrate and a writing feel improving layer that comes into contact with a touch pen. Specifically, as shown in Fig. 1, the writing feel improving sheet 1 according to this embodiment preferably includes a substrate 11 and a writing feel improving layer 12 provided on one side of the substrate 11.

[0035] 1. Elements 1-1. Substrate The substrate 11 may be appropriately selected from those suitable for touch panels in which a touch pen is used, and is preferably a plastic film that has good affinity with the writing feel improving layer 12. However, the substrate 11 may also be a glass plate or glass film.

[0036] Examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone film, polyether sulfone film, polyetherimide film, fluororesin film, polyamide film, acrylic resin film, polyurethane resin film, norbornene polymer film, cyclic olefin polymer film, cyclic conjugated diene polymer film, and vinyl alicyclic hydrocarbon polymer film, or laminate films thereof. Among these, polyethylene terephthalate film, polycarbonate film, and norbornene polymer film are preferred, as they can maintain the writing feel of the touch pen well in combination with the writing feel improving layer 12 described above, and polyethylene terephthalate film is particularly preferred. From the perspective of the SDGs, the material that constitutes the plastic film may be a material with a high biomass content, a material that can be recycled or reused, or a recycled or reused material.

[0037] Furthermore, in order to improve adhesion to layers (such as the writing feel improving layer 12 and the adhesive layer described below) provided on the surface of the substrate 11, one or both sides may be subjected to a surface treatment such as a primer treatment, an oxidation method, or a roughening method, as desired. Examples of oxidation methods include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, and ozone / ultraviolet treatment, while examples of roughening methods include sandblasting and solvent treatment. These surface treatment methods are appropriately selected depending on the type of substrate 11. As an example, a plastic film, particularly a polyethylene terephthalate film, on which an easy-adhesion layer has been formed by a primer treatment is preferably used.

[0038] The thickness of the substrate 11 is not particularly limited, but considering the use in a touch panel, it is preferably 25 to 500 μm, more preferably 38 to 400 μm, and even more preferably 50 to 300 μm.

[0039] 1-2. Writing Experience Improving Layer (1) Material of Writing Experience Improving Layer The writing experience improving layer 12 of the writing experience improving sheet 1 in this embodiment may be formed from any material as long as it satisfies the above-described physical property (distance between centers of gravity), but is preferably formed by curing the coating composition C described below. From the perspective of the SDGs, the material constituting the writing experience improving layer 12 may be a material with a high biomass content, a material that can be recycled or reused, or a recycled or reused material.

[0040] The coating composition C in this embodiment preferably contains a curable component and a filler, and further preferably contains a slip agent and a leveling agent, which makes it easier to form the writing feel improving layer 12 that satisfies the above-mentioned physical properties.

[0041] (1-1) Curable Component The curable component is a component that is cured by a trigger such as active energy rays or heat, and examples thereof include an active energy ray-curable component, a thermosetting component, etc. In the present embodiment, it is preferable to use an active energy ray-curable component from the viewpoints of the hardness of the writing feel improving layer 12 to be formed, the heat resistance of the substrate 11 (plastic film), etc.

[0042] Specific examples of the active energy ray-curable component include polyfunctional (meth)acrylate monomers, (meth)acrylate prepolymers, and active energy ray-curable polymers. Among these, polyfunctional (meth)acrylate monomers or (meth)acrylate prepolymers are more preferred. The polyfunctional (meth)acrylate monomers and (meth)acrylate prepolymers may be used alone or in combination. In this specification, the term "(meth)acrylate" refers to both acrylate and methacrylate. The same applies to other similar terms.

[0043] Examples of polyfunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphate di(meth)acrylate, allylated cyclohexyl di(meth)acrylate, isocyanurate di(meth)acrylate, and trimethylolpropane tri(meth)acrylate. Examples of the polyfunctional (meth)acrylate include polyfunctional (meth)acrylates such as acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate. These may be used alone or in combination of two or more.

[0044] Examples of the (meth)acrylate prepolymer include polyester acrylate, epoxy acrylate, urethane acrylate, and polyol acrylate prepolymers.

[0045] The polyester acrylate prepolymer can be obtained, for example, by esterifying the hydroxyl groups of a polyester oligomer having hydroxyl groups at both ends, which is obtained by condensation of a polycarboxylic acid and a polyhydric alcohol, with (meth)acrylic acid, or by esterifying the terminal hydroxyl groups of an oligomer obtained by adding an alkylene oxide to a polycarboxylic acid, with (meth)acrylic acid.

[0046] Epoxy acrylate prepolymers can be obtained, for example, by reacting (meth)acrylic acid with the oxirane ring of a relatively low molecular weight bisphenol epoxy resin or novolac epoxy resin to esterify it.

[0047] The urethane acrylate prepolymer can be obtained, for example, by esterifying a polyurethane oligomer obtained by reacting a polyether polyol or polyester polyol with a polyisocyanate with (meth)acrylic acid.

[0048] The polyol acrylate prepolymer can be obtained, for example, by esterifying the hydroxyl groups of a polyether polyol with (meth)acrylic acid.

[0049] The above prepolymers may be used singly or in combination of two or more.

[0050] (1-2) Filler The coating composition C preferably contains a filler, which makes it easier to satisfy the above-mentioned physical properties.

[0051] Examples of fillers include inorganic fine particles such as silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, and titanium dioxide; organic fine particles such as acrylic resin, polystyrene resin, polyethylene resin, and epoxy resin; and fine particles made of silicon-containing compounds having an intermediate structure between inorganic and organic (for example, the Tospearl series, which are silicone resin fine particles manufactured by Momentive Performance Materials Japan, Inc.). These fillers may be used alone or in combination of two or more.

[0052] The shape of the filler may be regular, such as spherical, or may be irregular, with no particular shape specified. However, from the viewpoint of making it easier to satisfy the above-mentioned physical properties, a regular shape is preferred, and a spherical shape is particularly preferred.

[0053] As a specific filler, it is preferable to use regular-shaped fine particles (e.g., silicone resin fine particles) made of a silicon-containing compound having an intermediate structure between inorganic and organic, and it is particularly preferable to use spherical silicone resin fine particles, which makes it easier to satisfy the above-mentioned physical properties.

[0054] The refractive index of the filler is preferably 1.2 to 3, more preferably 1.3 to 2, particularly preferably 1.35 to 1.6, and even more preferably 1.4 to 1.5, which makes it easier to achieve the desired optical properties.

[0055] The average particle size of the filler is preferably 0.1 to 20 μm, more preferably 0.5 to 18 μm, particularly preferably 1 to 16 μm, even more preferably 5 to 14 μm, and most preferably 8 to 12 μm. This makes it easier to satisfy the above-mentioned physical properties. The average particle size of the filler is measured by a centrifugal sedimentation light transmission method.

[0056] The content of the filler in coating composition C (excluding the content of silica nanoparticles, which will be described later) is preferably 1 to 50 parts by mass, more preferably 3 to 40 parts by mass, particularly preferably 4 to 30 parts by mass, even more preferably 5 to 20 parts by mass, and of these, preferably 6 to 10 parts by mass, relative to 100 parts by mass of the curable component. This makes it easier to satisfy the above-mentioned physical properties.

[0057] In this embodiment, it is also preferable to use silica nanoparticles in combination with the filler. This makes it easier to satisfy the above-mentioned physical properties. The average particle size of the silica nanoparticles is preferably 1 to 200 nm, more preferably 5 to 100 nm, and even more preferably 10 to 50 nm. The average particle size of the silica nanoparticles is measured by dynamic light scattering.

[0058] The silica nanoparticles may be modified with an organic substance to improve dispersibility. The silica nanoparticles are also preferably in the form of an organosol (colloidal). The organosol improves the dispersibility of the silica nanoparticles, improving the uniformity and light transmittance of the resulting writing feel improving layer 12.

[0059] The modification with an organic substance can be carried out by a conventional method. For example, CH ２ =C(CH ３ ) COO(CH ２ ) ３ Si(OCH ３ ) ３ The surface of the silica particles can be modified by adding a silane coupling agent having the above structure to an organosol of silica nanoparticles, heating the mixture to about 50° C., and stirring for several hours. The structure and amount of the silane coupling agent to be used are appropriately selected depending on the required degree of dispersibility of the silica nanoparticles.

[0060] As the dispersion solvent for the organosol, methyl ethyl ketone, methyl isobutyl ketone, etc., which have excellent compatibility with the polyfunctional (meth)acrylate and the leveling agent and excellent volatility when the writing feel improving layer 12 is formed, are preferred.

[0061] As the silica nanoparticles, commercially available products can be used, and among them, organosilica sol MEK-ST, MIBK-ST, etc. manufactured by Nissan Chemical Industries, Ltd. are preferably used.

[0062] When coating composition C contains silica nanoparticles, the content thereof is preferably 1 to 50 parts by mass, more preferably 4 to 40 parts by mass, particularly preferably 8 to 30 parts by mass, further preferably 12 to 25 parts by mass, and of these, preferably 16 to 22 parts by mass, relative to 100 parts by mass of the active energy ray-curable component. This makes it easier to satisfy the above-mentioned physical properties.

[0063] (1-3) Photopolymerization Initiator When ultraviolet light is used to cure the active energy ray-curable component, it is preferable that the coating composition C contains a photopolymerization initiator. This allows the active energy ray-curable component to be polymerized efficiently, and also reduces the polymerization and curing time and the ultraviolet light irradiation dose.

[0064] Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, Examples of such an ester include p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, etc. These may be used alone or in combination of two or more.

[0065] When the coating composition C contains a photopolymerization initiator, the content thereof is preferably 0.01 to 20 parts by mass, more preferably 0.1 to 15 parts by mass, and even more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the active energy ray-curable component, which makes it easier for the resulting writing feel improving layer 12 to have the desired hardness.

[0066] (1-4) Slipping Agent The coating composition C according to this embodiment preferably contains a slipping agent, which makes it easier to satisfy the above-mentioned physical properties.

[0067] Examples of slip agents include silicone-based slip agents, fluorine-based slip agents, and acrylic-based slip agents. Among these, fluorine-based slip agents are preferred because they make it easier to satisfy the above-mentioned physical properties. As the fluorine-based slip agent, a fluorine-based resin having a (meth)acrylate group polymerizable with the polyfunctional (meth)acrylate monomer or (meth)acrylate prepolymer as the curable component is preferred.

[0068] When coating composition C contains a slip agent, the content thereof is preferably 0.01 to 30 parts by mass, more preferably 0.05 to 20 parts by mass, particularly preferably 0.1 to 10 parts by mass, further preferably 0.5 to 5 parts by mass, and most preferably 1 to 2 parts by mass, per 100 parts by mass of the curable component. This makes it easier to satisfy the above-mentioned physical properties.

[0069] (1-5) Leveling Agent The coating composition C according to this embodiment preferably contains a leveling agent, which makes it easier to achieve the above-mentioned physical properties.

[0070] Examples of the leveling agent include silicone-based leveling agents, fluorine-based leveling agents, acrylic-based leveling agents, vinyl-based leveling agents, etc. Among these, silicone-based leveling agents are preferred from the viewpoint of easily satisfying the above-mentioned physical properties. Note that the leveling agents may be used alone or in combination of two or more.

[0071] The leveling agent may be modified or unmodified. Furthermore, the leveling agent may have a reactive group or may not have a reactive group. Among them, modified silicone is preferred, and polyether-modified silicone is particularly preferred.

[0072] When coating composition C contains a leveling agent, the content thereof is preferably 0.01 to 5.0 parts by mass, more preferably 0.1 to 3.0 parts by mass, particularly preferably 0.2 to 1.0 part by mass, and even more preferably 0.4 to 0.6 parts by mass, relative to 100 parts by mass of the curable component. This makes it easier to satisfy the above-mentioned physical properties.

[0073] (1-6) Other Components In addition to the above components, the coating composition C of the present embodiment may contain various additives. Examples of the various additives include dispersants, ultraviolet absorbers, infrared absorbers, antioxidants, light stabilizers, antistatic agents, silane coupling agents, antiaging agents, thermal polymerization inhibitors, colorants, refractive index modifiers, surfactants, storage stabilizers, plasticizers, lubricants, and antifoaming agents.

[0074] (2) Thickness The thickness of the writing feel improving layer 12 is preferably 0.5 to 50 μm, more preferably 1.0 to 30 μm, particularly preferably 1.5 to 20 μm, further preferably 2.0 to 10 μm, and most preferably 3.0 to 5.0 μm. This makes it easier to satisfy the above-mentioned physical properties.

[0075] When the thickness of the writing feel improving layer 12 is α (μm) and the average particle size of the filler is β (μm), the value of β / α preferably satisfies 0.001 to 100, more preferably satisfies 0.01 to 50, particularly preferably satisfies 0.1 to 20, even more preferably satisfies 0.5 to 10, more preferably satisfies 1 to 6, and most preferably satisfies 2 to 4. This makes it easier to satisfy the above-mentioned physical properties.

[0076] 1-3. Other Configurations The writing feel improving sheet 1 according to this embodiment may include an adhesive layer on the surface of the substrate 11 opposite the writing feel improving layer 12. The adhesive that constitutes the adhesive layer is not particularly limited, and known adhesives such as acrylic adhesives, rubber adhesives, and silicone adhesives can be used, and it is preferable to use an adhesive having a predetermined transparency.

[0077] When the writing feel improving sheet 1 according to the present embodiment includes the above-described adhesive layer, the writing feel improving sheet 1 according to the present embodiment may have a release film laminated on the surface of the adhesive layer opposite to the substrate 11. The release film is not particularly limited as long as it has the desired releasability on its release surface (the surface in contact with the adhesive layer), and any known release film, such as a resin film having one surface subjected to a release treatment with a release agent, can be used.

[0078] 2. Manufacturing Method of Writing Feel Improving Sheet The writing feel improving sheet 1 according to this embodiment can be manufactured by applying a coating liquid containing a coating composition for the writing feel improving layer 12, preferably coating composition C, and optionally a solvent, to the substrate 11 and curing it to form the writing feel improving layer 12.

[0079] The solvent can be used to improve coatability, adjust viscosity, adjust solid content concentration, etc., and any solvent can be used without particular limitation as long as it dissolves or disperses each component. Specific examples of the solvent include alcohols such as methanol, ethanol, isopropanol, butanol, and octanol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as ethyl acetate, butyl acetate, ethyl lactate, and γ-butyrolactone; ethers such as ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), diethylene glycol monobutyl ether (butyl cellosolve), and propylene glycol monomethyl ether; aromatic hydrocarbons such as benzene, toluene, and xylene; and amides such as dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0080] The coating composition may be applied by a conventional method, such as bar coating, knife coating, roll coating, blade coating, die coating, or gravure coating. After the coating composition is applied, the resulting film is preferably dried at 40 to 120°C for about 30 seconds to 5 minutes.

[0081] When the coating composition is active energy ray curable, such as coating composition C, the coating composition is cured by irradiating the coating film of the coating composition with active energy rays such as ultraviolet rays or electron beams. The ultraviolet irradiation can be carried out using a high-pressure mercury lamp, a Heraeus H lamp, a xenon lamp, or the like. The irradiation dose of ultraviolet rays has an illuminance of 50 to 1000 mW / cm. ２ , light intensity 50-1000mJ / cm ２ On the other hand, electron beam irradiation can be carried out using an electron beam accelerator or the like, and the dose of electron beam irradiation is preferably about 10 to 1000 krad.

[0082] The coating film of the coating composition can be irradiated with active energy rays in an air atmosphere or an inert gas atmosphere. Depending on the type of active energy ray-curable component, the coating composition can be cured well without being inhibited by oxygen by irradiating with active energy rays in an inert gas atmosphere.

[0083] Examples of inert gases include nitrogen, argon, and helium, with nitrogen and argon being preferred, and nitrogen being particularly preferred. The oxygen concentration in the inert gas atmosphere is preferably 5% or less, more preferably 3% or less, and particularly preferably 2% or less.

[0084] 3. Use of the Writing Experience Improving Sheet The writing experience improving sheet 1 according to this embodiment can be used as a sheet constituting the outermost layer of a touch panel (image display device with position detection function) in which a touch pen is used. Specifically, it is preferably used by being laminated on a cover material in a touch panel having a display module such as a liquid crystal (LCD) module, a light-emitting diode (LED) module, or an organic electroluminescence (organic EL) module, or a touch sensor. The writing experience improving sheet 1 is preferably laminated on the cover material by being attached via the aforementioned adhesive layer.

[0085] 4. Touch Panel with Writing Experience Improvement Sheet By laminating the writing experience improvement sheet according to the embodiment described above on a touch panel, a touch panel with a writing experience improvement sheet (including the concept of a display body with a touch panel component) can be obtained. Specifically, the touch panel with writing experience improvement sheet comprises a writing experience improvement sheet having a touch pen contact surface that comes into contact with a touch pen, and a touch panel, with the side of the writing experience improvement sheet opposite the touch pen contact surface laminated on the display surface side of the touch panel. The writing experience improvement sheet may be laminated directly on the display surface of the touch panel, or may be laminated on the display surface side of the touch panel via another member or layer.

[0086] The type and type of the touch panel are not particularly limited, and for example, capacitive, electromagnetic induction, resistive, surface acoustic wave (ultrasonic), infrared, and other touch panels can be used. Among these, capacitive touch panels are preferred from the viewpoint of easily reproducing an excellent writing feel, and capacitive touch panels that also incorporate electromagnetic induction are particularly preferred when taking into account the reproducibility of characters and the like written with a touch pen. The specific configurations of the capacitive and electromagnetic induction touch panels are not particularly limited, and conventionally known touch panels can be used.

[0087] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0088] For example, another layer may be interposed between the substrate 11 and the writing feel improving layer 12 in the writing feel improving sheet 1. In addition, another layer, such as a hard coat layer, may be provided on the surface of the substrate 11 opposite the writing feel improving layer 12.

[0089] In this specification, when it is stated that "X to Y" (X and Y are any numbers), it means "X or more and Y or less" unless otherwise specified, and also means "preferably greater than X" or "preferably smaller than Y". Furthermore, when it is stated that "X or more" (X is any number), it means "preferably greater than X" unless otherwise specified, and when it is stated that "Y or less" (Y is any number), it also means "preferably smaller than Y" unless otherwise specified.

[0090] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0091] Example 1 A mixture of 100 parts by mass of a polyfunctional urethane acrylate (A1; manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 575CB", containing a photopolymerization initiator) as an active energy ray-curable component (urethane acrylate-based prepolymer) and 100 parts by mass of fine particles (B1; manufactured by Momentive Performance Materials Japan, Inc., product name "Tospearl 1100", average particle size: 11.0 μm, refractive index: 1.43) made of a silicone resin (a silicon-containing compound having an intermediate structure between inorganic and organic) as a filler (expressed as a solid content equivalent value). The same applies to the components in (1), 20.0 parts by mass of organosilica sol (B2; manufactured by Nissan Chemical Industries, Ltd., product name "MIBK-ST", average particle size 10 nm) as silica nanoparticles, 1.2 parts by mass of fluorine-based resin (D1; manufactured by DIC Corporation, product name "Megafac RS-90") as a slip agent, and 0.4 parts by mass of polyether-modified silicone (E1; manufactured by Dow-Toray Industries, Inc., product name "SH28") as a silicone-based leveling agent were mixed in propylene glycol monomethyl ether to obtain a coating liquid of a coating composition.

[0092] The coating liquid of the coating composition obtained above was applied to the surface of the easy-adhesion layer side of a polyester film with an easy-adhesion layer (manufactured by Toray Industries, Inc., product name "Lumirror U40", thickness: 125 μm) as a substrate, and dried at 70° C. for 1 minute.

[0093] Next, under a nitrogen atmosphere, ultraviolet light was irradiated using an ultraviolet irradiation device (manufactured by iGraphics, product name "iGrantage ECS-401GX type") under the following conditions to form a writing feel improving layer having a thickness of 4.0 μm on the substrate, thereby obtaining a writing feel improving sheet. [UV irradiation conditions] Light source: high-pressure mercury lamp Lamp power: 2 kW Conveyor speed: 4.23 m / min Illuminance: 300 mW / cm ２ ・Light intensity: 250mJ / cm ２

[0094] A touch pen with a hard felt tip (Felt; manufactured by Wacom Co., Ltd., product name "ACK-20003", pen tip diameter: 0.5 mm) was selected as a writing implement for the writing feel improvement sheet.

[0095] Example 2 A writing feel improving sheet was produced in the same manner as in Example 1. A touch pen with a polyacetal nib (POM; manufactured by Wacom Co., Ltd., product name "ACK-20001", nib diameter: 0.5 mm) was selected as a writing implement for the writing feel improving sheet.

[0096] Comparative Example 1 A mixture of 100 parts by mass of an organic-inorganic hybrid resin (A2; manufactured by Arakawa Chemical Industries, Ltd., product name "Opstar Z7530", a mixture of a substance obtained by bonding acryloyl groups to silica fine particles (CV value: 28%) having an average particle size of 50 nm and a polyfunctional (meth)acrylate monomer, containing a photopolymerization initiator) as an active energy ray-curable component, 0.3 parts by mass of crosslinked polymethyl methacrylate spherical fine particles (B3; manufactured by Sekisui Plastics Co., Ltd., product name "Techpolymer SSX-101", average particle size: 1.5 μm) as a filler, 0.1 parts by mass of a fluorine-containing adamantane derivative having a polymerizable group (E2; manufactured by Neos Co., Ltd., product name "Ftergent 602A") as a fluorine-based leveling agent, and an acrylic resin having a carboxyl group and a hydroxyl group in the side chain (manufactured by Kyoeisha Chemical Co., Ltd., product name "Florene") as an additive (dispersant) was used. 0.3 parts by mass of propylene glycol monomethyl ether was mixed with propylene glycol monomethyl ether to obtain a coating liquid for the coating composition.

[0097] Using the coating liquid obtained above, a writing feel improving sheet was produced in the same manner as in Example 1. A touch pen with a polyacetal nib (POM; manufactured by Wacom Co., Ltd., product name "ACK-20001", nib diameter: 0.5 mm) was selected as a writing implement for the writing feel improving sheet.

[0098] Comparative Example 2 A mixture of 100 parts by mass of an organic-inorganic hybrid resin (A2; manufactured by Arakawa Chemical Industries, Ltd., product name "Opstar Z7530", a mixture of a substance obtained by bonding acryloyl groups to silica fine particles (CV value: 28%) having an average particle size of 50 nm and a polyfunctional (meth)acrylate monomer, containing a photopolymerization initiator) as an active energy ray-curable component, 3.0 parts by mass of crosslinked polymethyl methacrylate spherical fine particles (B3; manufactured by Sekisui Plastics Co., Ltd., product name "Techpolymer SSX-101", average particle size: 1.5 μm, refractive index: 1.49) as a filler, and a reactive silicone oligomer (D2; manufactured by The Nippon Synthetic Chemical Industry Co., Ltd., product name "Shikou" A coating solution of a coating composition was obtained by mixing 3.4 parts by mass of a polyether-modified silicone (E1; manufactured by Dow-Toray Industries, Inc., product name "SH28") as a silicone leveling agent, and 0.3 parts by mass of an acrylic resin having a carboxy group and a hydroxyl group on the side chain (manufactured by Kyoeisha Chemical Co., Ltd., product name "Florene G-700") as an additive (dispersant) in propylene glycol monomethyl ether.

[0099] Using the coating liquid obtained above, a writing feel improving sheet was produced in the same manner as in Example 1. A touch pen with a hard felt tip (Felt; manufactured by Wacom Co., Ltd., product name "ACK-20003", pen tip diameter: 0.5 mm) was selected as the writing implement for the writing feel improving sheet.

[0100] Comparative Example 3 A writing feel improving sheet was produced in the same manner as in Comparative Example 2. A touch pen with a polyacetal nib (POM; manufactured by Wacom Co., Ltd., product name "ACK-20001", nib diameter: 0.5 mm) was selected as a writing implement for the writing feel improving sheet.

[0101] Here, the formulations (solid content equivalent) of each coating composition when the active energy ray-curable component is taken as 100 parts by mass are shown in Table 1. Details of the abbreviations and the like shown in Table 1 are as follows. [Active energy ray-curable components] A1: Multifunctional urethane acrylate (manufactured by Arakawa Chemical Industries, Ltd., product name "Beamset 575CB", photopolymerization initiator included) A2: Organic-inorganic hybrid resin (manufactured by Arakawa Chemical Industries, Ltd., product name "Opstar Z7530", a mixture of a substance obtained by bonding acryloyl groups to silica fine particles (CV value: 28%) with an average particle size of 50 nm and a multifunctional (meth)acrylate monomer, photopolymerization initiator included) [Filler] B1: Microparticles made of silicone resin (silicon-containing compound having an intermediate structure between inorganic and organic) (manufactured by Momentive Performance Materials Japan, product name "Tospearl 1100", average particle size: 4.5 μm, refractive index: 1.43) B2: Organosilica sol (manufactured by Nissan Chemical Industries, Ltd., product name "MIBK-ST", average particle size 10 nm) B3: Cross-linked polymethyl methacrylate spherical particles (manufactured by Sekisui Plastics Co., Ltd., product name "Techpolymer SSX-101", average particle size: 1.5 μm, refractive index: 1.49) [Slip agent] D1: Fluorine-based resin (manufactured by DIC Corporation, product name "Megafac RS-90") D2: Reactive silicone oligomer (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., product name "Shiko UV-AF100") [Leveling agent] E1: Polyether-modified silicone (manufactured by Dow-Toray Industries, product name "SH28") E2: Fluorine-containing adamantane derivative with polymerizable group (manufactured by Neos Corporation, product name "Ftergent 602A")

[0102] [Test Example 1] (Measurement of Surface Roughness) For the surface of the writing feel improving layer side of the writing feel improving sheets manufactured in the Examples and Comparative Examples, the arithmetic mean surface roughness Ra (μm) and the ten-point mean surface roughness Rzjis (μm) were measured using a contact type roughness meter (manufactured by Mitutoyo Corporation, product name "SV3000S4") in accordance with JIS B0601:2013. The results are shown in Table 2.

[0103] The arithmetic mean surface roughness Ra (μm) and ten-point mean surface roughness Rzjis (μm) of the surface of "Campus (registered trademark) Loose-leaf" paper manufactured by Kokuyo S&T Co., Ltd., which was selected as the reference paper, were also measured in the same manner as above. The results are shown in Table 2.

[0104] [Test Example 2] (Measurement of rolling circle maximum height waviness) For the surface of the writing feel improving layer side of the writing feel improving sheets manufactured in the Examples and Comparative Examples, the rolling circle maximum height waviness (μm) was measured using a contact type roughness meter (manufactured by Mitutoyo Corporation, product name "SV3000S4") in accordance with JIS B0610:2001. The results are shown in Table 2.

[0105] The rolling circle maximum height waviness (μm) was also measured in the same manner as above for the surface of "Campus (registered trademark) loose-leaf" paper manufactured by Kokuyo S&T Co., Ltd., which was selected as the reference paper. The results are shown in Table 2.

[0106] [Test Example 3] (Measurement of friction coefficient) The four corners (areas that do not affect the measurement) of the substrate side of the writing feel improving sheets produced in the Examples and Comparative Examples were attached to one side of a glass plate (thickness: 1.2 mm) via double-sided adhesive tape, and this was used as a measurement sample.

[0107] The measurement sample was placed on a measurement cart of a static and dynamic friction tester (manufactured by Trinity Lab, product name "Tribomaster TL201Ts") with the writing feel improving layer side (touch pen contact surface) facing up. Note that the measurement cart moves linearly back and forth in a predetermined direction while maintaining the horizontality of the installation surface of the measurement sample when the static and dynamic friction tester is used.

[0108] Next, the touch pen was fixed to the static friction measuring device so that the pen tip was in contact with the touch pen contact surface. At this time, the touch pen was fixed at an angle of 45° between the touch pen and the touch pen contact surface. At this time, the rear end side of the touch pen was tilted to the opposite side to the traveling direction of the measurement cart, and the touch pen (tilted direction) in a plan view was parallel to the traveling direction.

[0109] Next, with a load of 200 g applied to the touch pen, the measurement cart was moved at a speed of 16.6 mm / sec to slide the touch pen on the touch pen contact surface (sliding distance: 100 mm), and the static and dynamic friction coefficients were calculated based on the friction force measured at that time. The results are shown in Table 2.

[0110] Furthermore, measurements were also carried out in the same manner as above for the combination of "Campus (registered trademark) Loose-leaf" paper manufactured by Kokuyo S&T Co., Ltd., selected as the reference paper, and "Uni (registered trademark) 2B" pencil manufactured by Mitsubishi Pencil Co., Ltd., selected as the reference pencil (reference pencil), to derive the static and dynamic coefficients of friction. The results are shown in Table 2.

[0111] Test Example 4 (Contact Angle Measurement) The contact angle of oleic acid on the surface of the writing feel improving layer of the writing feel improving sheets produced in the Examples and Comparative Examples was measured under the following conditions using a contact angle measuring meter (manufactured by Kyowa Interface Science Co., Ltd., product name "DM-701"). Note that oleic acid manufactured by Tokyo Chemical Industry Co., Ltd. was used as the oleic acid. The results are shown in Table 2. - Amount of oleic acid droplet: 2 μl - Measurement time: 3 seconds after dropping - Image analysis method: θ / 2 method

[0112] In the same manner as described above, the water contact angle on the surface of the writing feel improving layer of the writing feel improving sheets manufactured in the Examples and Comparative Examples was measured under the following conditions. The results are shown in Table 2. Water droplet volume: 2 μl Measurement time: 3 seconds after dropping Image analysis method: θ / 2 method

[0113] [Test Example 5] (Measurement of surface free energy) The contact angles of various liquid droplets on the surface of the writing feel improving layer of the writing feel improving sheets produced in the Examples and Comparative Examples were measured, and the surface free energy (mJ / m) was calculated based on the measured values ​​according to the Kitazaki-Hata theory. ２ ) was measured. The contact angle was measured using a contact angle meter (manufactured by Kyowa Interface Science Co., Ltd., product name "DM-701") by the sessile drop method in accordance with JIS R3257. For the droplets, diiodomethane was used as the "dispersion component" and 1-bromonaphthalene as the "dipole component" and distilled water as the "hydrogen bond component". The results are shown in Table 2.

[0114] [Test Example 6] (Haze Value Measurement) The haze values ​​(%) of the writing feel improving sheets produced in the Examples and Comparative Examples were measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH-5000") in accordance with JIS K7136: 2000. The results are shown in Table 2.

[0115] [Test Example 7] (Principal Component Analysis of Physical Properties) For the reference paper, reference pencil, and writing feel improvement sheets manufactured in the Examples and Comparative Examples, principal component analysis was performed using the arithmetic mean surface roughness Ra (μm) and ten-point mean surface roughness Rzjis (μm) obtained in Test Example 1, the rolling circle maximum height waviness (μm) obtained in Test Example 2, and the static friction coefficient and dynamic friction coefficient obtained in Test Example 3 as data to extract the first and second principal components, and obtain the reference center of gravity and the center of gravity of each writing feel improvement sheet. In performing this principal component analysis, as a preprocessing step, the average value was subtracted from the value of each data, and scaling was performed by dividing by the standard deviation, and the scaled data was used.

[0116] The coordinates of the obtained center of gravity (coordinates of a two-dimensional graph with the first principal component as the X-axis and the second principal component as the Y-axis) are shown in Table 2. Then, the distance between the reference center of gravity obtained above and the center of gravity of each writing feel improving sheet (distance between physical property centers of gravity) was calculated. The results are shown in Table 2.

[0117] The weight (degree of influence) of each data item in the first principal component and the weight (degree of influence) of each data item in the second principal component calculated by the above principal component analysis are shown in Table 3.

[0118] Here, when determining whether or not an arbitrary writing feel improvement sheet satisfies the physical properties (distance between centers of gravity) of the present invention, it is preferable to perform principal component analysis using each data of the arbitrary writing feel improvement sheet, each data of the desired reference writing object / reference writing implement, and each data of the writing feel improvement sheets (five types) manufactured in this example and comparative example.

[0119] [Test Example 8] (Principal Component Analysis of Sensory Evaluation) The four corners (areas that do not affect the measurement) of the substrate side of a reference paper (Campus (registered trademark) loose-leaf paper from KOKUYO S&T Co., Ltd.) and the writing feel improving sheets produced in the Examples and Comparative Examples were attached to one side of a glass plate (thickness: 1.2 mm) via double-sided adhesive tape, and these were used as samples.

[0120] Twenty panelists wrote on the reference paper of the above sample using a reference pencil ("Uni (registered trademark) 2B" manufactured by Mitsubishi Pencil Co., Ltd.) and the same twenty panelists wrote on the writing feel improvement sheet of the above sample using the touch pen selected for each example.

[0121] Each panelist evaluated the sensory evaluation items of writing comfort, pitch, pleasantness of sound, smoothness, softness, slipperiness, vibration, smoothness, and lightness on a 5-point scale (1 to 5). The average scores of the 20 panelists are shown in Table 4.

[0122] The sensory evaluation items were evaluated on a five-point scale (1 to 5) as follows, with the writing feel when writing with a reference pencil on reference paper being assigned a rating of "3." The "writing comfort" was evaluated as a value closer to 1 if the writing comfort was perceived to be worse than that of the reference pencil and reference paper, and a value closer to 5 if the writing comfort was perceived to be better than that of the reference pencil and reference paper. The "pitch" was evaluated as a value closer to 1 if the sound was perceived to be lower than that of the reference pencil and reference paper, and a value closer to 5 if the sound was perceived to be higher than that of the reference pencil and reference paper. The "sound pleasantness" was evaluated as a value closer to 1 if the sound was perceived to be less pleasant (more harsh) than that of the reference pencil and reference paper, and a value closer to 5 if the sound was perceived to be more pleasant than that of the reference pencil and reference paper. The "smoothness" was evaluated as a value closer to 1 if the feeling of unevenness was stronger than that of the reference pencil and reference paper, and a value closer to 5 if the feeling of smoothness was stronger than that of the reference pencil and reference paper. The "softness" was evaluated as a value closer to 1 if the feeling of hardness was stronger than that of the reference pencil and reference paper, and a value closer to 5 if the feeling of softness was stronger than that of the reference pencil and reference paper. The closer to 1 the "slipperiness" feels that the pencil has a stronger grip than the reference pencil and paper, and the closer to 5 the closer to 5 the slipperier it feels than the reference pencil and paper. The closer to 1 the "vibration" feels that the pencil has a stronger roughness than the reference pencil and paper, and the closer to 5 the closer to 5 the smoother it feels than the reference pencil and paper. The closer to 1 the "smoothness" feels that the pencil has a stronger firmness than the reference pencil and paper, and the closer to 5 the closer to 5 the smoother it feels than the reference pencil and paper. The closer to 1 the "lightness" feels that the pencil has a heavier writing feel than the reference pencil and paper, and the closer to 5 the closer to 5 the lighter it feels than the reference pencil and paper.

[0123] Next, the data obtained above was subjected to principal component analysis in the same manner as in Test Example 7 to extract the first and second principal components, and the reference center of gravity and the center of gravity of each writing feel improvement sheet were obtained. The coordinates of the obtained center of gravity (coordinates of a two-dimensional graph with the first principal component on the X axis and the second principal component on the Y axis) are shown in Table 2. The distance between the reference center of gravity obtained above and the center of gravity of each writing feel improvement sheet (sensory evaluation center of gravity distance) was then calculated. The results are shown in Table 2.

[0124] Table 5 shows the weight (degree of influence) of each data item in the first principal component and the weight (degree of influence) of each data item in the second principal component calculated by the above principal component analysis.

[0125] [Test Example 9] (Sensory Evaluation of Writing Feel) The four corners (areas that do not affect the measurement) of the substrate side of a reference paper (Campus (registered trademark) loose-leaf paper from KOKUYO S&T Co., Ltd.) and the writing feel improving sheets produced in the Examples and Comparative Examples were attached to one side of a glass plate (thickness: 1.2 mm) via double-sided adhesive tape, and these were used as samples.

[0126] Twenty panelists wrote on the reference paper of the above sample using a reference pencil ("Uni (registered trademark) 2B" manufactured by Mitsubishi Pencil Co., Ltd.) and the same twenty panelists wrote on the writing feel improvement sheet of the above sample using the touch pen selected for each example.

[0127] Each panelist compared the writing feel (X) when writing with a standard pencil on standard paper with the writing feel (Y) when writing with a touch pen on the writing feel improvement sheet, and evaluated the writing feel according to the following criteria: G: The writing feel (Y) had a vibration and resistance very similar to the writing feel (X), and was a good writing feel. NG: The writing feel (Y) had a different vibration and resistance from the writing feel (X), and was worse than the writing feel (X). Panelists who judged the writing feel as G by 16 or more were given an "O" rating, and those who judged the writing feel as NG by 16 or more were given an "X" rating. The results are shown in Table 2.

[0128]

[0129]

[0130]

[0131]

[0132]

[0133] As can be seen from Table 2, the writing feel improving sheets manufactured in the examples had small values ​​for the distance between the centers of gravity of physical properties and / or the distance between the centers of gravity of sensory evaluation obtained by principal component analysis, and thus obtained a writing feel similar to the writing feel when writing with a reference pencil on reference paper. Therefore, it can be seen that the values ​​for the distance between the centers of gravity of physical properties and / or the distance between the centers of gravity of sensory evaluation obtained by principal component analysis serve as indicators of writing feel in comparison with a reference writing implement or reference writing object (not limited to a pencil or paper).

[0134] The writing feel improving sheet of the present invention is suitably used as the outermost layer of a touch panel on which a touch pen is used.

[0135] 1... Writing feel improving sheet 11... Base material 12... Writing feel improving layer

Claims

1. A writing feel improving sheet having a surface that is in contact with a touch pen, comprising: the arithmetic mean roughness Ra (μm), ten-point mean roughness Rzjis (μm), and rolling circle maximum height waviness (μm) of the writing surface of a reference writing object; the static friction coefficient and kinetic friction coefficient measured by contacting a reference writing tool with the writing surface of the reference writing object, applying a load of 200 g to the writing tool, and linearly sliding the writing tool at a speed of 16.6 mm / sec while maintaining an angle of 45° between the writing tool and the writing surface; the arithmetic mean roughness Ra (μm), ten-point mean roughness Rzjis (μm), and rolling circle maximum height waviness (μm) of the surface of the writing feel improving sheet that is in contact with the touch pen; A writing feel improving sheet, characterized in that the distance between a reference center of gravity obtained by performing principal component analysis on the static friction coefficient and dynamic friction coefficient measured by bringing the tip of a specific touch pen into contact with the surface of the writing feel improving sheet that the touch pen comes into contact with, applying a load of 200 g to the touch pen and sliding the touch pen linearly at a speed of 16.6 mm / sec while maintaining the angle between the touch pen and the surface at 45°, and the center of gravity of the writing feel improving sheet is 4.8 or less.

2. The writing feel improving sheet according to claim 1, characterized in that the distance between the center of gravity of the writing feel improving sheet and a reference center of gravity obtained by performing a principal component analysis on the following data, each of which is evaluated on a five-point scale for the sensory evaluation items of writing comfort, pitch, pleasantness of sound, smoothness, softness, slipperiness, vibration sensation, smoothness, and lightness when writing is performed using the reference writing instrument on the reference writing object, and the following data, each of which is evaluated on a five-point scale for the sensory evaluation items of writing comfort, pitch, pleasantness of sound, smoothness, softness, slipperiness, vibration sensation, smoothness, and lightness when writing is performed using the specified touch pen on the writing feel improving sheet, is 1.4 or less.

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