JP2018173905A - Writing feel improvement sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a writing feel improvement sheet that is excellent in writing feel with a touch pen, reduces the occurrence of glare, and has excellent visibility of a display image and the excellent appearance.SOLUTION: A writing feel improvement sheet 1 comprises: a base material 11; a writing feel improvement layer 12 with which a touch pen comes into contact; and a light diffusion layer 13 that is provided between the base material 11 and writing feel improvement layer 12. The total haze of the writing feel improvement sheet 1 is 12% or more and 42% or less, and the writing feel improvement layer 12 contains spherical fine particles. A pen tip of the touch pen having a hard felt core with a pen tip diameter of 0.5 mm is moved at a speed of 100 mm/min under a pressure application condition of 3.92 N on a surface of the writing feel improvement layer 12 with which the touch pen comes into contact to measure pen tip resistance; an obtained moving distance-pen tip resistance chart is subjected to Fourier transformation; a frequency-amplitude chart is obtained through the transformation, and the average value of the amplitudes within a frequency range of 1 to 2 Hz acquired from the chart is 1.2 or more and 10 or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a writing quality improving sheet that can improve the writing quality with a touch pen in a touch panel or the like.

  In recent years, in various electronic devices, an image display device with a position detection function (touch panel) that serves both as a display device and an input unit has been widely used. In such a touch panel, there is an input by a touch pen in addition to an input by a finger. According to the touch pen, an input operation that is finer and more accurate than a finger is possible. However, the display module of a touch panel is usually hard. For this reason, the writing taste with a touch pen is unlikely to be good, unlike the writing taste when writing on paper with a pen such as a ballpoint pen or a fountain pen.

  In order to solve the problem of writing quality with the touch pen in the touch panel, a film for improving the writing quality (hereinafter sometimes referred to as “writing quality improving film” or “writing quality improving sheet”) is provided on the outermost surface of the touch panel. It is being considered to apply. As such a writing quality improving film, for example, Patent Document 1 includes a transparent base film and linear protrusions that form a network structure on at least one surface of the transparent base film, and the network structure is regular. Disclosed is a tactile film having a plurality of sections arranged in a row and having linear convex portions occupying an area of 5 to 80% with respect to the entire tactile film surface.

JP2015-054417A

  However, in the invention disclosed in Patent Document 1, the pen tip has a feeling of being caught or slipped, or the sound or vibration at the time of writing is different from the case of writing on the paper with the pen. I couldn't get a good taste when I wrote it. Further, in the conventional writing quality improving film, there is a case where the image light of the touch panel is scattered and the portion is glaring and so-called “glare” occurs. Further, in the conventional writing quality improving film, the display image may be blurred or white-brown, and the visibility and appearance of the display image may be deteriorated.

  The present invention has been made in view of such a situation, and provides a writing quality improving sheet that is excellent in writing quality with a touch pen, is suppressed in occurrence of glare, and is excellent in visibility and appearance of a display image. For the purpose.

  In order to achieve the above object, the present invention provides a writing quality comprising a base material, a writing quality improving layer with which the touch pen contacts, and a light diffusion layer provided between the base material and the writing quality improving layer. The improvement sheet, wherein the total haze of the writing quality improving sheet is 12% or more and 42% or less, the writing quality improving layer contains spherical fine particles, and the surface on which the touch pen of the writing quality improving layer contacts On the other hand, the pen tip of a hard felt core touch pen with a pen tip diameter of 0.5 mm is brought into contact in the vertical direction under a pressurizing condition with a load of 3.92 N, and the velocity is increased in any one direction parallel to the surface of the writing quality improving layer. Measuring the nib resistance while moving at 100 mm / min, Fourier transforming the chart of moving distance-nib resistance obtained, and obtaining from the frequency-amplitude chart obtained by the conversion, frequencies 1 to 2Hz range The average value of the amplitude in is 1.2 or more, providing a writing feeling improving sheet, characterized in that it is 10 or less (invention 1).

  The writing quality improving sheet according to the invention (Invention 1) has the above-described configuration and physical properties, so that the writing quality with the touch pen is excellent and the occurrence of glare caused by the writing quality improving sheet is suppressed, and the display image Therefore, the visibility and appearance of the display image are excellent.

  In the above invention (Invention 1), the pen tip of the hard felt core touch pen with a pen tip diameter of 0.5 mm is perpendicular to the surface of the touch improving layer of the writing quality improving layer in contact with the surface under a pressure of 3.92 N. The tip resistance is measured while moving at a speed of 100 mm / min in an arbitrary direction parallel to the surface of the writing quality improving layer, and the resulting moving distance-tip resistance resistance chart is Fourier transformed. The number of amplitude peaks in the frequency range of 1 to 2 Hz obtained from the frequency-amplitude chart obtained by the conversion is preferably 5 or more and 30 or less (Invention 2).

  In the said invention (invention 1 and 2), it is preferable that the said writing taste improvement layer is a layer which hardens the coating composition containing a sclerosing | hardenable component and the said spherical fine particle (invention 3).

  In the said invention (invention 1-3), it is preferable that the said light-diffusion layer is a layer which hardens the coating composition containing a sclerosing | hardenable component and light-diffusion microparticles | fine-particles (invention 4).

  The writing quality improving sheet according to the present invention is excellent in writing quality with a touch pen, is less susceptible to glare due to the writing quality improving sheet, and is excellent in visibility and appearance of a display image.

It is sectional drawing of the writing taste improvement sheet | seat which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
The writing quality improving sheet according to the present embodiment is a sheet constituting the outermost layer of the touch panel in which the touch pen is used, and is between the base material, the writing quality improving layer in contact with the touch pen, and the base material and the writing quality improving layer. And a light diffusion layer provided on the surface. Preferably, as shown in FIG. 1, the writing quality improving sheet 1 according to the present embodiment is formed by laminating a base material 11, a light diffusion layer 13, and a writing quality improving layer 12 in that order.

  The total haze of the writing quality improving sheet 1 is 12% or more and 42% or less. Moreover, the writing quality improving layer 12 contains spherical fine particles. Then, the pen tip of the hard felt core touch pen having a pen tip diameter of 0.5 mm is brought into contact with the surface of the touch improvement layer 12 in the vertical direction under a pressurizing condition of a load of 3.92 N to improve the writing quality. The nib resistance (mN) is measured while moving in an arbitrary direction parallel to the surface of the layer 10 at a speed of 100 mm / min, and a chart of the obtained moving distance (mm) −nib resistance (mN) is obtained. The average value of the amplitude in the frequency range of 1 to 2 Hz obtained from the Fourier transform and the frequency (Hz) -amplitude chart (-) obtained by the conversion is 1.2 or more and 10 or less (this pen The physical property related to the amplitude by the sliding test is sometimes referred to as “written physical property” below). The Fourier transform is performed using software (product name “Excel” (registered trademark), manufactured by Microsoft Corporation). The writing quality improving sheet 1 having the above-described configuration and physical properties is excellent in writing quality with a touch pen, and the occurrence of glare caused by the writing quality improving sheet 1 is suppressed, and the visibility and appearance of a display image are also excellent.

  In particular, the light diffusion layer 13 is provided between the base material 11 and the writing quality improving layer 12, the total haze of the writing quality improving sheet 1 is 12% or more, and the writing quality improving layer 12 contains spherical fine particles. Thus, the occurrence of glare caused by the writing quality improving sheet 1 is suppressed. Further, when the total haze is 42% or less, blurring of the display image can be suppressed, and the visibility of the display image can be favorably maintained. Furthermore, when the writing quality improving layer 12 contains spherical fine particles, the whiteness of the writing quality improving sheet 1 can be suppressed and the appearance can be maintained well. In addition, the total haze of the writing quality improving sheet 1 in this embodiment is the haze (total of internal haze and external haze) of the entire laminate of the base material 11, the light diffusion layer 13, and the writing quality improving layer 12. Moreover, the haze in this specification shall be the value measured according to JISK7136: 2000.

  From the viewpoint of suppressing glare, the total haze is preferably 14% or more, particularly preferably 16% or more, and more preferably 18% or more. Further, from the viewpoint of the visibility of the display image, the total haze is preferably 40% or less, particularly preferably 35% or less, and further preferably 30% or less.

  In particular, when the writing quality improving layer 12 contains spherical fine particles and the average value of the amplitude is in the above range, a favorable feeling of resistance and friction is imparted to the writing quality with a touch pen. Combined with these sensations, the writing feel of a touch pen is close to that of writing on paper with a pen.

  The definition of the amplitude in the frequency range of 1 to 2 Hz is a characteristic that humans recognize as "writing taste" especially when the vibration at the time of writing is regarded as a superposition of a plurality of vibrations having various frequencies. This is because the present inventors have empirically found that a simple vibration is a vibration having a frequency in the range of 1 to 2 Hz.

  In addition, as a touch pen, for example, a touch pen having a pen tip diameter of 0.1 to 5 mm, a polyacetal core touch pen, and the like can be used. Is obtained. In addition, the “pen” used as a reference for writing in this specification includes a ballpoint pen, a felt-tip pen, a fountain pen, and the like, but preferably uses a fountain pen as a reference.

  Here, the “pen tip resistance” refers to the resistance applied to the pen tip when the touch pen is moved under the above conditions. The “average value of amplitude” refers to a value obtained by taking the sum of the maximum value and the minimum value of the peak in the frequency range of 1 to 2 Hz and dividing the sum by the number. Further, the “number of peaks” refers to the number of peaks having an amplitude of 1.5 or more in a frequency range of 1 to 2 Hz.

  From the viewpoint of writing with a touch pen, the average value of the amplitude is preferably 1.3 or more, and more preferably 1.5 or more. The average value of the amplitude is preferably 4 or less, particularly preferably 2.8 or less, and more preferably 2.5 or less.

  From the viewpoint of further improving the writing quality with a touch pen, the number of amplitude peaks (number of amplitudes) is preferably 5 or more, particularly preferably 6 or more, and more preferably 7 or more. The amplitude number is preferably 30 or less, particularly preferably 20 or less, and more preferably 15 or less.

  Further, from the viewpoint of further improving the writing quality with the touch pen, the maximum value of the amplitude (maximum amplitude value) is preferably 1.3 or more, particularly preferably 2.0 or more, and 2. It is preferably 4 or more. The maximum amplitude value is preferably 10 or less, particularly preferably 8 or less, and further preferably 5 or less.

  A specific method of obtaining the above moving distance (mm) -pen tip resistance force (mN) chart is as shown in a test example described later.

1. Each member (1) base material As the base material 11, what is necessary is just to select suitably from what was suitable for touchscreens in which a touch pen is used, Preferably a plastic film with favorable affinity with the light-diffusion layer 13 is selected. However, the base material 11 may be glass.

  Examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate and polyethylene naphthalate, polyolefin films such as polyethylene film and polypropylene film, 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, poly Etherimide film, fluororesin film Plastic films such as polyamide film, acrylic resin film, polyurethane resin film, norbornene polymer film, cyclic olefin polymer film, cyclic conjugated diene polymer film, vinyl alicyclic hydrocarbon polymer film, or laminates thereof A film is mentioned. Among these, a polyethylene terephthalate film, a polycarbonate film, a norbornene polymer film or the like that can maintain the writing quality of the touch pen in the combination with the writing quality improving layer 12 described above is preferable, and a polyethylene terephthalate film is particularly preferable.

  Moreover, in the said base material 11, for the purpose of improving adhesiveness with the layers (light-diffusion layer 13, the adhesive layer mentioned later, etc.) provided in the surface, a primer process and an oxidation method may be applied to one side or both sides as desired. The surface treatment can be performed by an uneven method or the like. Examples of the oxidation method include corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet treatment, and examples of the unevenness method include a sand blast method and a solvent treatment method. These surface treatment methods are appropriately selected according to the type of the substrate 11. As an example, a plastic film, particularly a polyethylene terephthalate film, on which an easy adhesion layer is formed by primer treatment, is preferably used.

  The thickness of the substrate 11 is preferably 15 to 300 μm, particularly preferably 30 to 200 μm, and more preferably 90 to 150 μm.

(2) Writing quality improvement layer (2-1) Material of writing quality improvement layer The writing quality improvement layer 12 of the writing quality improvement sheet 1 in this embodiment contains spherical fine particles, and satisfies the above-mentioned writing quality properties. As long as it consists of material, it may form from any material, However, Preferably, it forms by hardening the coating composition C1 demonstrated below. According to the coating composition C1, it is easy to form the writing quality improving layer 12 that satisfies the above-mentioned writing quality properties. Moreover, according to the coating composition C1, by containing spherical fine particles, generation | occurrence | production of glare is suppressed and white-browning etc. are also suppressed and an external appearance becomes favorable.

  The coating composition C1 in this embodiment preferably contains a curable component and spherical fine particles.

(2-1-1) Curable component A curable component is a component which hardens | cures with triggers, such as an active energy ray and a heat | fever, for example, an active energy ray curable component, a thermosetting component, etc. are mentioned. In this embodiment, it is preferable to use an active energy ray-curable component from the viewpoint of the hardness of the writing quality improving layer 12 to be formed, the heat resistance of the base material 11 (plastic film), and the like.

  The active energy ray-curable component is preferably one that can be cured by irradiation with active energy rays to exhibit a predetermined hardness and achieve the physical properties described above in relation to spherical fine particles.

  Specific active energy ray curable components include polyfunctional (meth) acrylate monomers, (meth) acrylate prepolymers, active energy ray curable polymers, etc., among which polyfunctional (meth) acrylates. It is preferably a monomer and / or a (meth) acrylate prepolymer, and more preferably a polyfunctional (meth) acrylate monomer. The polyfunctional (meth) acrylate monomer and the (meth) acrylate prepolymer may be used alone or in combination. In the present specification, (meth) acrylate means both acrylate and methacrylate. The same applies to other similar terms.

  Examples of multifunctional (meth) acrylate monomers include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol diene. (Meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified di (meth) acrylate phosphoric acid, allylation Cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipenta Lithritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, propionic acid modified dipenta Examples include polyfunctional (meth) acrylates such as erythritol 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 individually by 1 type and may be used in combination of 2 or more type.

  On the other hand, examples of the (meth) acrylate-based prepolymer include polyester acrylate-based, epoxy acrylate-based, urethane acrylate-based, polyol acrylate-based prepolymers, and the like.

  Examples of the polyester acrylate-based prepolymer include esterification of a hydroxyl group of a polyester oligomer having hydroxyl groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid, It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding alkylene oxide to carboxylic acid with (meth) acrylic acid.

  The epoxy acrylate prepolymer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it.

  The urethane acrylate-based prepolymer can be obtained, for example, by esterifying, with (meth) acrylic acid, a polyurethane oligomer obtained by a reaction between polyether polyol or polyester polyol and polyisocyanate.

  The polyol acrylate prepolymer can be obtained, for example, by esterifying the hydroxyl group of the polyether polyol with (meth) acrylic acid.

  The above prepolymers may be used alone or in combination of two or more.

  It is also preferable to use an organic-inorganic hybrid resin as the active energy ray-curable component. Preferred examples of the organic / inorganic hybrid resin include a substance obtained by bonding an organic compound having a polymerizable unsaturated group to inorganic fine particles such as silica via a silane coupling agent. Note that the silica fine particles contained in the organic-inorganic hybrid resin have a function as a silica sol and also a function as a binder, and are not included in the spherical fine particles described later.

  When the organic / inorganic hybrid resin is used, it becomes easy to obtain the above-mentioned writing taste properties in relation to the spherical fine particles due to the action as a silica sol, and the surface hardness of the formed writing taste improving layer 12 can be improved. it can.

(2-1-2) Spherical fine particles The shape of the spherical fine particles is spherical, preferably true spherical. The spherical fine particles may be either inorganic fine particles or organic fine particles, but organic fine particles are preferable from the viewpoint of improving the optical properties of the writing quality improving layer 12.

  Examples of organic fine particles include silicone fine particles, melamine resin fine particles, acrylic resin fine particles (for example, polymethyl methacrylate resin fine particles), acrylic-styrene copolymer fine particles, polycarbonate fine particles, polyethylene fine particles, polystyrene. Fine particles, benzoguanamine resin fine particles, and the like. Those resins may be cross-linked. Among these, acrylic resin fine particles are preferable from the viewpoint of optical properties and hardness, polymethyl methacrylate resin fine particles are particularly preferable, and cross-linked polymethyl methacrylate resin fine particles are more preferable.

  The average particle diameter of the spherical fine particles is preferably 1.7 μm or more, particularly preferably 2.0 μm or more, and more preferably 2.5 μm or more. The average particle size of the spherical fine particles is preferably 15 μm or less, more preferably 10 μm or less, particularly preferably 8 μm or less, and further preferably 5 μm or less. When the average particle diameter of the spherical fine particles is in the above range, the above-described writing physical properties are easily satisfied, and the writing taste of the touch pen becomes closer to the feeling when writing on paper with a pen.

  In addition, the average particle diameter of the fine particles in the present specification is obtained by measuring the primary particle diameter by a laser diffraction method. The average particle diameter determined by the laser diffraction method was obtained by sufficiently stirring 1.2 g of fine particles and 98.8 g of isopropyl alcohol as a measurement sample, and using a laser diffraction scattering type particle size distribution measuring device (product name “LA” manufactured by Horiba, Ltd.). -920 ").

Regarding the particle size distribution of the spherical fine particles, the coefficient of variation (CV value) of the particle size represented by the following formula is 3% or more from the viewpoint that the writing quality improving layer 12 makes it easy to obtain the above-mentioned writing quality properties. In particular, it is preferably 5% or more, and more preferably 10% or more. From the same viewpoint, the CV value is preferably 200% or less, more preferably 175% or less, particularly preferably 150% or less, and further preferably 30% or less. preferable.
Coefficient of variation of particle size (CV value) (%) = (standard deviation particle size / average particle size) × 100
In addition, let the coefficient of variation (CV value) of a particle size be the value measured with the laser diffraction scattering type particle size distribution measuring apparatus (the product name "LA-920" by Horiba Ltd.).

  The content of the spherical fine particles in the coating composition C1 is preferably 3% by mass or more, particularly preferably 7% by mass or more, and further preferably 10% by mass or more. Further, the content of the spherical fine particles is preferably 40% by mass or less, particularly preferably 30% by mass or less, and further preferably 15% by mass or less. When the content of the spherical fine particles is in the above range, the above-mentioned writing physical properties are easily obtained.

(2-1-3) Photopolymerization initiator When ultraviolet rays are used as the active energy ray for curing the active energy ray-curable component, the coating composition C1 preferably contains a photopolymerization initiator. . By containing the photopolymerization initiator in this manner, the active energy ray-curable component can be efficiently polymerized, and the polymerization curing time and the amount of ultraviolet irradiation can be reduced.

  Examples of such a 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, p-phenylbenzophenone, 4,4′-di Tylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2 4,6-trimethylbenzoyl-diphenyl-phosphine oxide and the like. These may be used alone or in combination of two or more.

  The content of the photopolymerization initiator in the coating composition C1 is preferably 0.01 parts by mass or more, particularly 0.1 parts by mass or more, as a lower limit with respect to 100 parts by mass of the active energy ray-curable component. It is preferable that it is 1 mass part or more. Moreover, it is preferable that it is 20 mass parts or less as an upper limit, It is especially preferable that it is 10 mass parts or less, Furthermore, it is preferable that it is 5 mass parts or less.

(2-1-4) Other components The coating composition C1 may contain various additives in addition to the components described above. Examples of various additives include dispersants, leveling agents, ultraviolet absorbers, antioxidants, light stabilizers, antistatic agents, silane coupling agents, anti-aging agents, thermal polymerization inhibitors, colorants, and surfactants. , Storage stabilizers, plasticizers, lubricants, antifoaming agents, wettability improvers, coating surface improvers and the like. By containing a dispersant among the above, the dispersibility of the spherical particles is improved, and the above-mentioned writing properties are easily satisfied.

  As a dispersant, a carboxy group, a hydroxyl group, a sulfo group, a primary amino group, a secondary amino group, a tertiary amino group, an amide group, a quaternary ammonium base, a pyridium base, a sulfonium base, and a phosphonium base are included in the molecule. A compound having one or more polar groups selected from the group is preferable, and a compound having one or more polar groups of a carboxy group and a hydroxyl group is particularly preferable. One or more polar groups may be introduced into the molecule.

  When the compound as a dispersant has a plurality of polar groups, the basic skeleton of the compound is preferably composed of an ester chain, a vinyl chain, an acrylic chain, an ether chain, a urethane chain, or the like. Specifically, acrylic resins, urethane resins, polyester resins and alkyd resins are preferable, acrylic resins, urethane resins and polyester resins are particularly preferable, and acrylic resins are more preferable.

  The polar groups may be randomly arranged in the molecule, but are preferably arranged in the side chain. Therefore, the compound as the dispersant is preferably an acrylic resin having a carboxy group and / or a hydroxyl group in the side chain.

  The weight average molecular weight of the compound as the dispersant is not particularly limited, but can be selected from a wide range of from 100 to 900,000. In addition, a dispersing agent may be used individually by 1 type, and may be used in combination of 2 or more type.

  The blending amount of the dispersant is preferably 0.01 to 1 part by mass, particularly preferably 0.03 to 0.5 part by mass with respect to 100 parts by mass of the active energy ray-curable component.

(2-2) Thickness of the writing quality improving layer The thickness of the writing quality improving layer 12 is preferably 0.5 μm or more, particularly preferably 1 μm or more, and more preferably 3 μm or more, as a lower limit. Preferably there is. When the lower limit of the thickness of the writing quality improving layer 12 is as described above, the above-described writing physical properties are easily satisfied, and good scratch resistance is obtained. In addition, the thickness of the writing quality improving layer 12 is preferably 20 μm or less, particularly preferably 15 μm or less, and more preferably 10 μm or less, as an upper limit. When the upper limit value of the thickness of the writing quality improving layer 12 is the above, the above-described writing physical properties are easily satisfied.

(2-3) Haze of the writing quality improving layer In order to make the total haze of the writing quality improving sheet 1 within the above range, the haze of the writing quality improving layer 12 is preferably 6% or more, particularly 10% or more. It is preferable that it is 16% or more. The haze of the writing quality improving layer 12 is preferably 43% or less, particularly preferably 40% or less, and further preferably 35% or less. The method for measuring the haze of the writing quality improving layer 12 is as shown in the test examples described later.

(3) Light Diffusion Layer (3-1) Light Diffusion Layer Material The light diffusion layer 13 of the writing quality improving sheet 1 in the present embodiment has the total haze of the writing quality improving sheet 1 in the above range, and the above-mentioned writing quality properties. As long as it is made of a material satisfying the above, it may be made of any material, but is preferably formed by curing a coating composition C2 described below. According to the coating composition C2, it is easy to form the light diffusion layer 13 that satisfies the above total haze and writing properties. Moreover, according to the coating composition C2, the surface hardness (pencil hardness) of the writing quality improvement sheet | seat 1 obtained becomes high, and the writing quality improvement sheet | seat 1 becomes the thing excellent in abrasion resistance.

  The coating composition C2 in this embodiment preferably contains a curable component and light diffusing fine particles.

(3-1-1) Curable component As the curable component in the coating composition C2, the same curable components as those in the coating composition C1 described above can be used. Among these, it is preferable to use a polyfunctional (meth) acrylate monomer or an organic-inorganic hybrid resin from the viewpoint of improving hardness and curling.

  As the polyfunctional (meth) acrylate-based monomer, from the viewpoint of improving hardness and curling suppression, a tetrafunctional or higher-functional non-modified polyfunctional (meth) acrylate monomer such as pentaerythritol tetra (meth) acrylate, and an ethylene oxide-modified diester are used. One or two alkylene oxide-modified polyfunctional (meth) acrylate monomers such as pentaerythritol hexa (meth) acrylate are preferred, and it is particularly preferred to use them in combination. By using them in combination, hardness improvement and curl suppression can each be achieved satisfactorily. The mass ratio between the tetrafunctional or higher non-modified polyfunctional (meth) acrylate monomer and the alkylene oxide-modified polyfunctional (meth) acrylate monomer is preferably 100: 0 to 10:90, particularly 85: It is preferably 15 to 25:75, and more preferably 70:30 to 40:60.

  The amount of alkylene oxide added to the alkylene oxide-modified polyfunctional (meth) acrylate monomer is preferably 1 mol or more, particularly preferably 3 mol or more, and more preferably 5 mol or more. The addition amount is preferably 35 mol or less, particularly preferably 25 mol or less, and more preferably 20 mol or less.

(3-1-2) Light diffusing fine particles As the light diffusing fine particles, any light diffusion fine particles may be used as long as the total haze described above can be set in the above range. Inorganic fine particles such as clay, talc, titanium dioxide; Organic translucent fine particles such as acrylic resin such as polymethyl methacrylate resin, polystyrene resin, polymethyl methacrylate-polystyrene copolymer, polyethylene resin, epoxy resin; Examples thereof include fine particles (for example, Tospearl series manufactured by Momentive Performance Materials Japan) made of a silicon-containing compound having an intermediate structure between inorganic and organic, such as silicone resin. Among these, acrylic resin fine particles, polymethyl methacrylate-polystyrene copolymer fine particles, and fine particles composed of silicon-containing compounds having an intermediate structure between inorganic and organic have excellent dispersibility with respect to the curable component and uniform optical properties. Is preferable. The above light diffusing fine particles may be used alone or in combination of two or more.

  As the shape of the light diffusing fine particles, spherical fine particles with uniform light diffusion, particularly spherical fine particles are preferable. The average particle diameter of the light diffusing fine particles by the laser diffraction method is preferably 0.1 μm or more, particularly preferably 1 μm or more, and further preferably 2 μm or more. The average particle diameter is preferably 20 μm or less, more preferably 10 μm or less, particularly preferably 8 μm or less, and further preferably 3 μm or less. When the average particle diameter is within the above range, the total haze value can be easily set within the above-described range without hindering the light transmittance of the light diffusion layer 13.

  Regarding the particle size distribution of the light diffusing fine particles, the coefficient of variation (CV value) of the particle size is preferably 3% or more, particularly 5% or more, from the viewpoint of easily making the total haze described above within the above range. It is preferable that it is 10% or more. From the same viewpoint, the CV value is preferably 100% or less, more preferably 80% or less, particularly preferably 60% or less, and further preferably 30% or less. preferable.

  The content of the light diffusing fine particles in the coating composition C2 is preferably 0.5% by mass or more, particularly preferably 1% by mass or more, and further preferably 3% by mass or more. Further, the content of the light diffusing fine particles is preferably 30% by mass or less, more preferably 25% by mass or less, particularly preferably 20% by mass or less, and further preferably 9% by mass or less. Preferably there is. When the content of the light diffusing fine particles is in the above range, the above-described total haze value is easily obtained.

(3-1-3) Photopolymerization initiator When ultraviolet rays are used as the active energy ray for curing the active energy ray-curable component, the coating composition C2 preferably contains a photopolymerization initiator. . As a photoinitiator, the thing similar to the photoinitiator in the coating composition C1 mentioned above can be used. Moreover, preferable content is the same as that of the coating composition C1.

(3-1-4) Other components The coating composition C2 may contain various additives in addition to the components described above. Examples of various additives include leveling agents, UV absorbers, antioxidants, light stabilizers, antistatic agents, silane coupling agents, anti-aging agents, thermal polymerization inhibitors, colorants, surfactants, and storage stability. Agents, plasticizers, lubricants, antifoaming agents, wettability improvers, coating surface improvers and the like.

(3-2) Thickness of the light diffusion layer The thickness of the light diffusion layer 13 is preferably 0.5 μm or more, more preferably 0.7 μm or more, and particularly preferably 1 μm or more. Furthermore, it is preferable that it is 2 micrometers or more. Further, the thickness of the writing quality improving layer 12 is preferably 20 μm or less, particularly preferably 15 μm or less, and further preferably 10 μm or less. When the thickness of the light diffusion layer 13 is in the above range, the above-described total haze value is easily obtained.

(3-3) Internal haze of light diffusion layer In order to make the total haze of the writing quality improving sheet 1 within the above range, the internal haze of the light diffusion layer 13 is preferably 3% or more, particularly 5% or more. It is preferable to be 7% or more. Further, the internal haze of the light diffusion layer 13 is preferably 45% or less, particularly preferably 40% or less, and more preferably 35% or less. The method for measuring the internal haze of the light diffusion layer 13 is as shown in the test examples described later.

2. Method for producing writing quality improving sheet The writing quality improving sheet 1 according to the present embodiment is preferably produced as follows. That is, a coating composition for forming the light diffusion layer 13, preferably a coating composition C2 and, if desired, a coating solution containing a solvent is applied to the substrate 11 and cured to form the light diffusion layer 13. To do. Thereafter, a coating composition for forming the writing quality improving layer 12, preferably a coating liquid containing the coating composition C 1 and optionally a solvent is applied to the light diffusing layer 13 and cured to be cured. 12 is formed.

  The solvent can be used for improving coating properties, adjusting the viscosity, adjusting the solid content concentration, etc., and can be used without particular limitation as long as the curable components are dissolved and the fine particles are dispersed. .

  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 cellosorb), ethylene glycol monoethyl ether (ethyl cellosorb), diethylene glycol monobutyl ether (butyl cellosorb), propylene glycol monomethyl ether; aromatic hydrocarbons such as benzene, toluene and xylene; dimethylformamide Amides such as dimethylacetamide and N-methylpyrrolidone.

  Application of the coating liquid of the coating composition may be performed by a conventional method, for example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, or a gravure coating method. When the coating composition coating liquid is applied, the coating film is preferably dried at 40 to 120 ° C. for about 30 seconds to 5 minutes.

When the coating composition is active energy ray curable like the coating compositions C1 and C2, the coating composition is cured by irradiating the coating film of the coating composition with active energy rays such as ultraviolet rays and electron beams. To do. UV irradiation, high-pressure mercury lamp, a fusion H lamp, can be carried out by a xenon lamp or the like, the dose of ultraviolet ray is illuminance 50~1000mW / cm ^2, about the amount of light 50~1000mJ / cm ² is preferred. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.

3. Physical property It is preferable that the pencil hardness by the side of the writing quality improvement layer 12 of the writing quality improvement sheet 1 which concerns on this embodiment is 3H or more. Thereby, the writing taste improving sheet 1 becomes excellent in scratch resistance. The pencil hardness is a value measured according to JIS K5600.

4). Other Configurations The writing quality improving sheet 1 according to the present embodiment is further different if the writing quality improving layer 12 is the outermost surface and the light diffusion layer 13 exists between the base material 11 and the writing quality improving layer 12. You may have a layer of. For example, an adhesive layer may be formed on the surface of the substrate 11 opposite to the light diffusion layer 13, and a release sheet may be further laminated on the adhesive layer.

  As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, those usually used for optical applications can be used. For example, acrylic pressure-sensitive adhesive, rubber pressure-sensitive adhesive, silicone pressure-sensitive adhesive, urethane pressure-sensitive adhesive, polyester-based An adhesive, a polyvinyl ether adhesive, etc. are mentioned. Among these, an acrylic pressure-sensitive adhesive that expresses desired adhesiveness and has excellent optical properties and durability is preferable.

  The thickness of the pressure-sensitive adhesive layer is preferably 5 to 1000 μm, particularly preferably 7 to 500 μm, and further preferably 10 to 250 μm.

5. Use of writing quality improvement sheet The writing quality improvement sheet 1 which concerns on this embodiment is a sheet | seat which comprises the outermost layer of the touchscreen (image display apparatus with a position detection function) in which a touch pen is used. Specifically, it is 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, an organic electroluminescence (organic EL) module, or a touch sensor. Is preferred. It is preferable to perform the lamination | stacking to the cover material of the writing taste improvement sheet | seat 1 by sticking through the adhesive layer as mentioned above.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, another layer may be interposed between the base material 11 and the light diffusion layer 13 in the writing quality improving sheet 1 and between the light diffusion layer 13 and the writing quality improving layer 12.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
(1) Formation of light diffusion layer Organic-inorganic hybrid resin (product name “OPSTAR Z7530”, manufactured by Arakawa Chemical Industries, Ltd.) as a curable component, a substance formed by bonding an acryloyl group to silica fine particles and a polyfunctional (meth) acrylate 100 parts by mass (expressed in terms of solid content; hereinafter the same applies to other components) and true spherical polymethyl methacrylate-polystyrene copolymer having an average particle size of 2.5 μm 6 parts by mass of fine particles (refractive index: 1.55, CV value: 28%) were mixed to obtain a coating composition C2 for a light diffusion layer. The coating composition C2 was diluted with propylene glycol monomethyl ether to prepare a coating solution.

On the surface of the easy-adhesion layer side of the polyester film with an easy-adhesion layer (product of Toyobo Co., Ltd., product name “Cosmo Shine A4300”, thickness: 125 μm) as a base material, the coating solution for the light diffusion layer obtained above Was applied and dried at 70 ° C. for 1 minute. Next, ultraviolet light is irradiated under the following conditions by an ultraviolet irradiation device (manufactured by GS Yuasa Corporation, product name “Nitrogen purged small conveyor type UV irradiation device CSN2-40”) in the atmosphere, and light diffusion of 3 μm in thickness is performed. A layer was formed.
[UV irradiation conditions]
・ Light source: High pressure mercury lamp ・ Lamp power: 1.4 kW
・ Conveyor speed: 1.2m / min
Illuminance: 100 mW / cm ²
・ Light intensity: 240 mJ / cm ²

  The thickness of the light diffusion layer was determined by measuring the total thickness of the base material and the light diffusion layer using a constant pressure thickness meter (product name “MH-15M” manufactured by Nikon Corporation). It was calculated by subtracting the thickness of the substrate.

(2) Formation of a writing quality improving layer Organic inorganic hybrid resin as a curable component (manufactured by Arakawa Chemical Industry Co., Ltd., product name “OPSTAR Z7530”, a substance in which an acryloyl group is bonded to silica fine particles and polyfunctionality (meta) (Mixed product of acrylate monomer) 100 parts by mass, 5 parts by mass of true spherical crosslinked polymethyl methacrylate (refractive index: 1.49, CV value: 28%) having an average particle diameter of 3 μm, and side chain as a dispersant Was mixed with 0.2 part by mass of an acrylic resin having a carboxy group and a hydroxyl group (manufactured by Kyoeisha Chemical Co., Ltd., product name “Floren G700”) to obtain a coating composition C1 for a taste improving layer. The coating composition C1 was diluted with propylene glycol monomethyl ether to prepare a coating solution.

  On the exposed surface of the light diffusing layer formed on the substrate, the coating solution for the writing quality improving layer obtained above was applied and dried at 70 ° C. for 1 minute. Next, ultraviolet rays were irradiated under the same conditions as in the formation of the light diffusing layer to form a 4 μm-thickness improving layer to obtain a writing quality improving sheet.

  In addition, the thickness of the writing quality improving layer in the writing quality improving sheet is measured using a constant pressure thickness meter (manufactured by Nikon Corporation, product name “MH-15M”), and the total thickness of the writing quality improving sheet is measured. It calculated by subtracting the thickness of a base material and a light-diffusion layer from the said total thickness.

[Examples 2-3, Comparative Examples 1-4]
A writing quality improving sheet was prepared in the same manner as in Example 1 except that the materials and blending ratios of the coating compositions C1 and C2 and the thicknesses of the light diffusion layer and the writing quality improving layer were changed as shown in Table 1.

Here, details of the abbreviations and the like described in Table 1 are as follows.
A: Organic-inorganic hybrid resin (Arakawa Chemical Industries, product name “OPSTAR Z7530”, a mixture of a substance in which an acryloyl group is bonded to silica fine particles and a polyfunctional (meth) acrylate monomer)
B: Pentaerythritol tetraacrylate C: Ethylene oxide-modified dipentaerythritol hexaacrylate (ethylene oxide 12 mol)
D: Multifunctional urethane acrylate (Arakawa Chemical Industries, product name “Beam Set 575CB”)
E: True spherical polymethyl methacrylate-polystyrene copolymer fine particles having an average particle diameter of 2.5 μm (refractive index: 1.55, CV value: 28%)
F: Spherical silicone fine particles having an average particle diameter of 2 μm (fine particles made of silicon-containing compound having an intermediate structure between inorganic and organic) (product name “Tospearl 120” manufactured by Momentive Performance Materials Japan, Inc., refractive index) : 1.42, CV value: 20%)
G: True spherical crosslinked polymethyl methacrylate having an average particle size of 3 μm (refractive index: 1.49, CV value: 28%)
H: True spherical crosslinked polymethyl methacrylate having an average particle diameter of 5 μm (refractive index: 1.49, CV value 12%)
I: Amorphous silica fine particles having an average particle diameter of 4.5 μm (refractive index: 1.46, CV value: 35%)
J: Acrylic resin having a carboxy group and a hydroxyl group in the side chain (manufactured by Kyoeisha Chemical Co., product name “Floren G700”)
K: 1-hydroxycyclohexyl phenyl ketone (photopolymerization initiator)

[Test Example 1] (Measurement of haze)
The total haze (%) of the writing quality improving sheet produced in Examples and Comparative Examples was measured according to JIS K7136: 2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name “NDH-5000”). did. The results are shown in Table 2.

  The haze of the base material used in Examples and Comparative Examples was measured in the same manner as described above. Also, one of the release films of the optical adhesive sheet (product name “OPTERIA MO-T015”, manufactured by Lintec Co., Ltd.) having release films on both sides of the transparent adhesive layer was peeled off, and the exposed adhesive layers were compared with Examples and Comparative Examples. It stuck on the light-diffusion layer in the laminated body of the base material and light-diffusion layer which were obtained in the middle of manufacture in the example. Subsequently, the other peeling film in the said optical adhesive sheet was peeled, and the haze of the obtained laminated body was measured like the above, and the internal haze of the said laminated body was acquired. And the internal haze (%) of the light-diffusion layer was computed by subtracting the haze of the said base material from the internal haze of the said laminated body. The results are shown in Table 2.

  Furthermore, the haze (%) of the writing quality improving layer was calculated by subtracting the haze of the base material and the internal haze of the light diffusion layer from the total haze of the writing quality improving sheet. The results are shown in Table 2.

[Test Example 2] (Pen sliding test)
The writing quality improving sheets produced in Examples and Comparative Examples were placed on a glass substrate with the writing quality improving layer side up. The pen tip of a hard felt core touch pen (product name "ACK-2003" manufactured by Wacom Co., Ltd.) with a nib diameter of 0.5 mm is vertically applied to the surface of the writing quality improving layer under a pressure of 3.92 N. It was moved at a speed of 100 mm / min in an arbitrary direction parallel to the surface of the writing quality improving sheet while being in contact with (the direction in which the axis of the nib is perpendicular to the surface of the writing quality improving layer). In addition, the said touch pen was attached to the measurement trolley | bogie, and the said stylus was made to slide on the writing improvement layer by moving the said trolley | bogie.

  The nib resistance at the time of movement was measured using a universal testing machine (product name “Tensilon” manufactured by Orientec Co., Ltd.) to obtain a chart of moving distance (mm) −nib resistance (mN). Then, the obtained moving distance (mm) -pen tip resistance force (mN) chart is Fourier-transformed by software (product name “Excel” (registered trademark), manufactured by Microsoft Corporation), and frequency (Hz) −amplitude (−) A chart was obtained. From the frequency (Hz) -amplitude (-) chart, the average value, maximum value (maximum amplitude value), and number of peaks (amplitude number) of the amplitude in the frequency range of 1 to 2 Hz were obtained. The results are shown in Table 2.

[Test Example 3] (Sensory evaluation of writing taste)
The writing quality improving sheets produced in Examples and Comparative Examples were placed on a glass substrate with the writing quality improving layer side up. On the surface of the writing quality improving layer, a panelist performs a predetermined writing operation in a simulated manner using a hard felt core touch pen having a nib diameter of 0.5 mm (product name “ACK-2003”). The following writing taste was evaluated. The results are shown in Table 2. In addition, each writing taste was evaluated on a five-ply paper (manufactured by KOKUYO S & T, product name “Campus Note A Rule No-201A”), and a fountain pen (manufactured by ST DuPont, product name “Line D 41074”). It was done based on the writing taste when writing with "Black Lacquer &Palladium").

(1) Resistance feeling Resistance feeling as writing taste was evaluated according to the following criteria.
◎: There is moderate resistance when writing, and the pen is hard to slip ○: There is some resistance when writing, and the pen is allowed to slip ×: Resistance when writing is too small, and the pen slides

(2) Smoothness The smoothness as writing quality was evaluated according to the following criteria.
◎: Pen is very easy to slide when writing ○: Pen is easy to slide when writing ×: There is a problem with pen sliding when writing

[Test Example 4] (Evaluation of glare)
A tablet terminal (Apple) with the writing quality improving sheets manufactured in the examples and comparative examples, with the writing quality improving layer side up and displaying the entire surface in green (RGB values (R, G, B) = 0, 255, 0) The product was placed on the surface of a display screen having a product name “iPad (registered trademark)” and resolution: 264 ppi), and glare was evaluated visually by the following criteria. The results are shown in Table 2.
◯: No glare caused by the writing quality improving sheet was confirmed.
X: The glare resulting from a writing taste improvement sheet | seat was confirmed.

[Test Example 5] (Evaluation of appearance)
The writing quality improving sheets produced in the examples and comparative examples were placed on the side of the writing quality improving layer side up, and the black acrylic resin was passed through a transparent double-sided PSA sheet (product name “OPTEIA MO-T015” manufactured by Lintec Corporation). It was affixed on one side of a board (product name “Acrylite L502” manufactured by Mitsubishi Rayon Co., Ltd.) And the external appearance of the writing taste improvement sheet | seat was visually observed under the 3 wavelength fluorescent lamp, and the external appearance was evaluated on the following references | standards. The results are shown in Table 2.
A: Almost no white browning was observed.
◯: Slight browning was observed.
X: White brown was strongly observed.

[Test Example 6] (Evaluation of display image visibility)
The surface of the display screen of the tablet terminal (manufactured by Apple Inc., product name “iPad (registered trademark)”, resolution: 264 ppi) with the writing quality improving layer side up, with the writing quality improving sheet produced in the examples and comparative examples Placed on. Various images were displayed on the tablet terminal, and the image blur was observed by five evaluators. Based on the result, display image visibility was evaluated according to the following criteria. The results are shown in Table 2.
A: All five evaluators judged that there was no image blur.
A: 3 to 4 out of 5 evaluators judged that there was no blur in the image.
X: Three or more out of five evaluators judged that the image was blurred.

[Test Example 7] (Measurement of pencil hardness)
Using the pencil scratch coating film hardness tester (product name “NP”, manufactured by Toyo Seiki Seisakusho Co., Ltd.), the pencil hardness of the surface on the side of the writing quality improving layer in the writing quality improving sheet produced in Examples and Comparative Examples, The measurement was performed according to JIS K5600. The results are shown in Table 2.

[Test Example 8] (Steel Wool Hardness Test)
About the surface of the writing quality improving layer side (surface of the writing quality improving layer) in the writing quality improving sheet produced in the examples and comparative examples, using # 0000 steel wool, 10 cm, 10 reciprocations at a load of 250 g / cm ^2. Rubbed. The surface of the writing quality improving layer was visually confirmed under a three-wavelength fluorescent lamp, and the steel wool hardness (abrasion resistance) was evaluated according to the following criteria. The results are shown in Table 2.
◯: No scratch was confirmed.
X: Scratches were confirmed.

  As is clear from Table 2, the writing quality improving sheet produced in the examples was excellent in writing quality with a touch pen, and the occurrence of glare caused by the writing quality improving sheet was suppressed. Further, the writing taste improving sheet produced in the example had good visibility and appearance of the display image, and had a relatively high surface hardness.

  The writing quality improving sheet of the present invention is suitably used as the outermost layer of a touch panel in which a touch pen is used.

DESCRIPTION OF SYMBOLS 1 ... Writing quality improvement sheet 11 ... Base material 12 ... Writing quality improvement layer 13 ... Light-diffusion layer

Claims (4)

A writing quality improving sheet comprising a base material, a writing quality improving layer in contact with the touch pen, and a light diffusion layer provided between the base material and the writing quality improving layer,
The total haze of the writing quality improving sheet is 12% or more and 42% or less,
The writing quality improving layer contains spherical fine particles;
A pen tip of a hard felt core touch pen having a pen tip diameter of 0.5 mm is brought into contact with a surface in contact with the surface of the touch improvement layer of the writing quality improving layer in a vertical direction under a pressure of 3.92 N, and the writing quality improving layer is The pen tip resistance is measured while moving in one arbitrary direction parallel to the surface of the tip at a speed of 100 mm / min, and the obtained moving distance-pen tip resistance force chart is Fourier transformed, and the frequency obtained by the conversion -The writing quality improvement sheet | seat characterized by the average value of the amplitude in the range of frequency 1-2Hz acquired from an amplitude chart being 1.2-10.   A pen tip of a hard felt core touch pen having a pen tip diameter of 0.5 mm is brought into contact with a surface in contact with the surface of the touch improvement layer of the writing quality improving layer in a vertical direction under a pressure of 3.92 N, and the writing quality improving layer is The pen tip resistance is measured while moving in one arbitrary direction parallel to the surface of the tip at a speed of 100 mm / min, and the obtained moving distance-pen tip resistance force chart is Fourier transformed, and the frequency obtained by the conversion The writing quality improving sheet according to claim 1, wherein the number of amplitude peaks in a frequency range of 1 to 2 Hz acquired from the amplitude chart is 5 or more and 30 or less.   The writing quality improving sheet according to claim 1 or 2, wherein the writing quality improving layer is a layer obtained by curing a coating composition containing a curable component and the spherical fine particles.   The writing light improvement according to any one of claims 1 to 3, wherein the light diffusion layer is a layer formed by curing a coating composition containing a curable component and light diffusion fine particles. Sheet.

Images