KR20160107107A - Scattering prevention sheet - Google Patents

Abstract

The present invention provides an internally adhesive scattering preventing sheet capable of ensuring excellent Newton ring preventing properties and certainly preventing close placement on a glass surface or a deflecting plate. To this end, the scattering preventing sheet is attached on the inner surface of a display device of a member for constituting the display device, has a layer containing particles and resin, and has a plurality of block parts formed on the surface thereof due to the particles. The average particle size of the particles is 0.5-10 m, and a content thereof is less than 0.3 wt% of a resin solid constituting the layer. The resin is obtained by introducing a photocurable unsaturated group in a thermoplastic resin or a thermosetting resin, and a weight average molecular weight thereof is 70000 or more. The resin is an ionization radiation hardening resin including more than 15 wt% and 50 wt% or less of a compound having a glass transition temperature of 45C or more in the total resin.

Description

{Scattering prevention sheet}

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a scattering-prevention sheet adhered to a surface opposite to a touch surface of a capacitive touch panel.

The capacitance type touch panel has both a surface type and a projection type. Both detect the input position by grasping the change in capacitance caused at the touch position. Therefore, there is an advantage that input can be performed with a light touch as much as touching the screen because the input does not need any force as compared with the resistance film type involving the mechanical contact deformation (the transparent conductive film is lost).

In order to protect transparent substrates such as glass or plastic and to prevent scattering during breakage, such a capacitive touch panel is formed by attaching a hard coat film or a protective sheet (scattering-preventive sheet) . The scatter preventive sheet is also called an inner attaching sheet when it is used on the side opposite to the touch surface, and it is required that no Newton ring is generated when contacting the glass plate or the deflecting plate of the display device located below.

Patent Document 1 discloses a capacitive touch panel-equipped display device and a capacitive touch panel which are less prone to occurrence of Newton ring and have a bright touch surface. In this technique, a protective sheet having a hard coat layer having fine irregularities is adhered to the surface opposite to the touch surface of the touch panel, and irregularities are provided on the surface facing the display (liquid crystal display).

Japanese Patent No. 5440747

Since the protective sheet described in Patent Document 1 has fine irregularities of 400 nm or less almost uniformly distributed over the entire uneven surface, the effect of preventing Newton ring is limited, and for example, the occurrence of Newton rings It is considered impossible to inhibit it.

The applicant of the present invention proposed a technology that combines anti-scattering property, anti-Newtoning property and anti-sparkle property (Japanese Patent Application No. 2013-198380) as a hard coat film for a front surface of a display device such as a touch panel, It is demonstrated that a hard coat film satisfying the above performance can be obtained by using a resin having a specific reactive functional group together with an ionizing radiation curable resin as the resin of the hard coat layer and having a specific glass transition temperature and molecular weight. This technique can achieve good performance as a hard coat film for the front surface, but it can not necessarily achieve satisfactory performance as an inner sheet for attachment (shatterproof sheet) used inside the display device.

Based on the technology disclosed in Japanese Patent Application No. 2013-198380, the inventors of the present invention have conducted studies on a configuration for obtaining a performance particularly suited to the anti-scattering sheet. As a result, by adjusting the particle diameter and the content of the particles contained in the hard coat layer to a specific range and adjusting the state (state) of the convex portion formed by the particles, more excellent anti-ringing property can be obtained as the inner side attachment sheet And it is possible to surely prevent the glass plate from contacting with the glass plate or the deflecting plate, thereby reaching the present invention.

That is, the scattering-prevention sheet of the present invention includes a layer containing particles and a resin, and has a plurality of convexities due to the particles on the surface thereof. The scattering- ), Said particles having an average particle size of 0.5 to 10 mu m and a content of less than 0.3 wt% of the resin solid constituting said layer. The resin is preferably a resin having a photopolymerizable unsaturated group introduced into a thermoplastic resin or a thermosetting resin and having a weight average molecular weight of 70,000 or more and containing a compound having a glass transition temperature of 45 ° C or higher in an amount exceeding 15% Radiation curable resin.

In addition, the scattering-prevention sheet of the present invention preferably has an area of a flat region having no convexity due to the particles of 98% or more.

In addition, the shake preventive sheet of the present invention preferably has a haze (JIS K7136: 2000) of 2.0% or less.

In the present invention, the term " display device " is used broadly to include a display device (for example, a display device with a touch panel) or the like in which a display device is combined with an accessory or an additional member such as a touch panel.

According to the present invention, it is possible to effectively prevent the occurrence of Newton ring and sparkle in a touch panel-equipped display device or the like, and to prevent the occurrence of watermarks due to close contact between the scattering-prevention sheet and the display surface. Further, the watermark is a phenomenon in which the light propagation path in each region is largely different in the region (close contact region) in which the scattering prevention sheet and the display surface are in close contact with each other (the non-contact region) And the boundary between the non-contact region and the non-contact region are conspicuous.

1 is a view for explaining an example of a capacitive touch panel-mounted display apparatus using the scattering-prevention sheet of the present invention.
Fig. 2 is a cross-sectional view showing the anti-scattering sheet as an example of the present invention.
3 is a cross-sectional view showing a conventional anti-scattering sheet.

An embodiment of the anti-scattering sheet of the present invention will be described below.

The light-scattering-prevention sheet of the present embodiment is a sheet adhered to a surface facing the inside of a display device of a member constituting a display device, and has a layer containing particles and resin.

In the present embodiment, the display device is a touch panel-equipped display device in which a capacitive touch panel and a display device are arranged with a predetermined gap therebetween, and the scatter prevention sheet is a surface facing the display device of the capacitive touch panel .

Fig. 1 shows an example of a display device with a touch panel equipped with the scattering-prevention sheet of the present embodiment. As shown in the figure, the capacitive touch panel-equipped display device 35 has a structure in which the display device 34 such as a liquid crystal display and the capacitive touch panel 32 are adhered to each other by the pressure- And a predetermined gap is provided between the display device 34 and the capacitive touch panel 32. [ The anti-scattering sheet 1 is adhered to the opposite side of the touch surface 31 of the capacitive touch panel 32 via the adhesive layer 3.

The anti-scattering sheet 1 comprises a base material 4 and a layer 2 containing particles and a resin as shown in Fig. The layer 2 containing the particles and the resin functions as a hard coat layer which has irregularities on the surface and functions as an anti-Newton ring layer and protects the capacitive touch panel 32. Hereinafter, the hard coat layer 2 ). The anti-scattering sheet 1 is disposed so that the hard coat layer 2 faces the gap. 2 shows that the adhesive layer 3 for adhering the scattering-prevention sheet 1 to the capacitive touch panel 32 is provided on the base material 4. The adhesive layer 3 is provided on the touch panel side Or may be formed when the anti-scattering sheet 1 is adhered, and it is not essential to the anti-scattering sheet 1 itself. The shatterproof sheet may be a single layer hard coat layer as well as a hard coat layer laminated on one side or both sides of the substrate sheet.

The anti-scattering sheet 1 of the present embodiment is characterized by using a specific ionizing radiation curable resin as the resin and having a specific surface shape by setting the particle diameter and the content of the particles to a specific range. As a result, the light transmittance and the haze The effect of preventing the occurrence of Newton ring while satisfying the optical characteristics of the touch surface 31, the effect of preventing adhesion to the surface of the display device located below, typically the glass surface or the deflection plate, and the effect of preventing sparkle The occurrence prevention effect is obtained.

The specific structure of the base material and the hard coat layer will be described below by taking the scattering-prevention sheet 1 having the structure shown in Fig. 2 as an example below.

The substrate 4 is not particularly limited as long as it is a film having high optical transparency. For example, a transparent film formed of a material such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene, polypropylene, polystyrene, triacetylcellulose, and acrylic. Among these, stretching processing, particularly, biaxially stretched polyethylene terephthalate film is preferable because of excellent mechanical strength and dimensional stability. It is also preferable to conduct corona discharge treatment on the surface of the base material 4 or to improve adhesion with the hard coat layer 2 by providing an easy adhesion layer. The thickness of the base material 4 is generally 6 to 500 占 퐉, preferably 23 to 200 占 퐉.

The hard coat layer 2 includes a binder resin 5 and particles 6 and has a plurality of projections 8 on the surface thereof due to the particles 6.

The binder resin (5) of this embodiment includes an ionizing radiation curable resin and a specific resin. Specific resin is a compound having a photo-curable unsaturated group introduced into a thermoplastic resin or a thermosetting resin, having a weight average molecular weight of 70,000 or more and a glass transition temperature of 45 ° C or more.

First, the ionizing radiation curable resin will be described. As the ionizing radiation curable resin, crosslinking and curing by irradiation with ionizing radiation (ultraviolet ray or electron beam) is used. As such, a mixture of one kind or a mixture of two or more of a photocationic polymerizable photopolymerizable resin, a photopolymerizable photopolymerizable prepolymer or a photopolymerizable monomer may be used.

Examples of the light-ion polymerizable resin include epoxy resins such as bisphenol-based epoxy resins, novolak-type epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins, and vinyl ether-based resins.

As the photopolymerizable prepolymer, acrylic type prepolymer having two or more acryloyl groups in one molecule and having a three-dimensional network structure by crosslinking and curing is particularly preferably used. As the acrylic prepolymer, urethane acrylate, polyester acrylate, epoxy acrylate, melamine acrylate, polyfluoroalkyl acrylate, and silicone acrylate can be used. These acrylic prepolymers can be used alone, but it is preferable to add a photopolymerizable monomer in order to improve the crosslinking curability and further improve the hardness of the functional layer.

Examples of the photopolymerizable monomer include monofunctional acrylic monomers such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate and butoxyethyl acrylate, 1,6-hexanediol diacrylate, Bifunctional acrylic monomers such as pentyl glycol diacrylate, diethylene glycol diacrylate, polyethylene glycol diacrylate, and hydroxypivalic acid ester neopentyl glycol diacrylate, dipentaerythritol hexaacrylate, trimethylpropane triacrylate, And polyfunctional acrylic monomers such as pentaerythritol triacrylate, and the like.

In addition to the photopolymerizable resin, the photopolymerizable prepolymer or the photopolymerizable monomer described above, when the ionizing radiation curable resin is cured by ultraviolet irradiation, it is preferable to contain a curing auxiliary such as a photopolymerization initiator, a photopolymerization accelerator, and an ultraviolet sensitizer.

Examples of the photopolymerization initiator include photo radical polymerization initiators such as acetophenone, benzophenone, Michler's ketone, benzoin, benzylmethyl ketal, benzoyl benzoate,? -Acyloxime ester and thioxanthone, onium salts, sulfonic acid esters , An organic metal complex, and the like. Examples of ultraviolet sensitizers include n-butylamine, triethylamine, tri-n-butylphosphine and the like.

In addition, the photopolymerization accelerator is capable of accelerating the curing rate by alleviating the polymerization trouble caused by air at the time of curing, and examples thereof include p-dimethylaminobenzoyl isoamyl ester and p-dimethylaminobenzoic acid ethyl ester.

Also, an ionizing radiation-curable organic-inorganic hybrid resin may be used as the ionizing radiation curing resin. An ionizing radiation-curable organic-inorganic hybrid resin (hereinafter sometimes briefly referred to as "organic-inorganic hybrid resin") is different from an example of a composite represented by glass fiber reinforced plastic (FRP) The inorganic component and the organic component react with each other by irradiation with ionizing radiation to form a coating film.

Examples of the inorganic component in the organic-inorganic hybrid resin include metal oxides such as silica and titania, preferably silica. As the silica, a reactive silica into which a photosensitive group having photopolymerization reactivity is introduced on the surface can be mentioned. The content of the inorganic component in the organic-inorganic hybrid resin is preferably 10% by weight or more, more preferably 20% by weight, preferably 65% by weight or less, and more preferably 40% by weight or less.

As the organic component in the organic-inorganic hybrid resin, a compound having a polymerizable unsaturated group capable of polymerizing with the inorganic component (preferably reactive silica) (for example, a polyfunctional unsaturated organic compound having two or more polymerizable unsaturated groups in the molecule, Unsaturated organic compounds having a polymerizable unsaturated group, and the like).

Next, the resin A will be described.

Resin A is obtained by introducing a photocurable unsaturated group into a thermoplastic resin or a thermosetting resin.

Examples of the thermoplastic resin include a thermoplastic resin such as a polyester resin, an acrylic resin, a polycarbonate resin, a cellulose resin, an acetal resin, a vinyl resin, a polyethylene resin, a polystyrene resin, a polypropylene resin, Polyimide resins, and fluorine resins. Examples of the thermosetting resin include a polyester acrylate resin, a polyurethane acrylate resin, an epoxy acrylate resin, an epoxy resin, a melamine resin, a phenol resin, and a silicone resin.

The photocurable unsaturated group introduced into the thermoplastic resin or the thermosetting resin is preferably an ionizing radiation curable unsaturated group. Specific examples thereof include ethylenic unsaturated bonds such as a (meth) acryloyl group, a styryl group, a vinyl group and an allyl group, and an epoxy group. More preferably a (meth) acryloyl group.

In the present embodiment, a resin having a glass transition temperature (Tg) of 45 占 폚 or higher, preferably 80 占 폚 or higher, more preferably 90 占 폚 or higher is used as the resin A. By using the resin A having a Tg of 45 캜 or higher together with the ionizing radiation curable resin, the flow of the ionizing radiation curable resin can be easily suppressed in the course of curing.

The Tg referred to herein is before the resin A is cured.

In the present embodiment, resin A having a weight average molecular weight (Mw) of 70,000 or more, preferably 80,000 or more is used. By using the resin A having an Mw of 70,000 or more with an ionizing radiation curable resin, the flow of the ionizing radiation curable resin can be easily suppressed in the course of curing.

The molecular weight distribution of the compound is measured by gel permeation chromatography (GPC) equipped with, for example, a differential refractive index detector (RID), and the standard molecular weight (Mw) It can be calculated as a calibration curve.

The effect of using the resin A in combination will be described with reference to Fig.

Generally, an ionizing radiation curable resin has a property of being cured while flowing in the course of its curing. Therefore, when a cured product is to be obtained by using the curable composition comprising the particles (6) and the binder resin (5) comprising an ionizing radiation curable resin, the ionizing radiation curable resin flows during curing of the curable composition, As a result, as shown in Fig. 3, a "wave 5a '" of the binder resin 5a centering on the particle 6a is generated to form a lens shape. In the case of the conventional anti-scattering sheet 1a, this wave was one of the causes of spark generation.

In the present embodiment, by using a predetermined amount of the specific resin A together with the ionizing radiation curable resin, the flow of the ionizing radiation curable resin during the curing process is suppressed. As a result, as shown in Fig. 2, the occurrence of "wave" of the binder resin 5 after curing is suppressed (substantially not corresponding to the wave 5a 'in Fig. 3, the same applies hereinafter) It is possible to more effectively prevent the occurrence of sparkle in the anti-scattering sheet 1 after curing.

Also, the hardness of the coating film can be increased as compared with the case where the photocurable unsaturated group contained in the resin A strengthens the bond with the ionizing radiation curable resin and, as a result, the photocurable unsaturated group is not introduced.

The ionizing radiation curable resin is preferably in the range of 50 wt% or more and less than 85 wt%, more preferably 60 wt% or more and 80 wt% or less, and more preferably 60 wt% or more and 75 wt% or less based on the total resin component constituting the hard coat layer More preferable.

The above-mentioned resin A is preferably contained in an amount of more than 15% by weight, preferably 20% by weight or more and 40% by weight or less, more preferably 25% by weight or more and 40% by weight or less in the total resin constituting the hard coat layer Do. When the blending amount of the resin A is set to an amount exceeding 15% by weight, the generation of the wave can be sufficiently suppressed and the sparkling can be easily prevented. When the content is 50% by weight or less, it is easy to prevent the decrease of the coating film strength.

The dispersibility of the particles is improved by blending the blending amount of the resin A in the range of more than 15 wt% to 50 wt% or less, whereby the surface property of the coating film is appropriately adjusted.

The above-mentioned ionizing radiation curable resin and a compound or resin other than the resin A may be added to the hard coat layer of the present embodiment within a range that does not hinder the function thereof.

Next, the particles 6 included in the hard coat layer 2 will be described. Examples of the particles include inorganic particles (e.g., calcium carbonate, magnesium carbonate, barium sulfate, aluminum hydroxide, silica, kaolin, clay, talc and the like), resin particles (e.g., acrylic resin particles, polystyrene resin particles, Polyethylene resin particles, benzoguanamine resin particles, epoxy resin particles, etc.). Among them, spherical fine particles are preferable from the viewpoint of easiness of handling and control of surface shape. Further, the resin particles are suitable because they are easy to bring the difference in refractive index between the binder resin and the binder resin, easily generate sparkles, and are difficult to inhibit transparency.

Since the average particle size of the particles 6 differs depending on the thickness of the hard coat layer 2, it can not be said to be uniform, but is preferably not less than 0.1 탆, more preferably not less than 0.5 탆, still more preferably not less than 1 탆 , Preferably 10 m or less, and more preferably 8 m or less. Sparkling can be prevented easily by setting the average particle diameter of the particles (6) to 10 mu m or less. When the average particle diameter is 0.1 mu m or more, the anti-glare property and the anti-Newton ring property can be easily exhibited. In this specification, the " average particle size " and " variation coefficient of particle size distribution " of the particles (6) are values measured by the Coulter counter method.

The particles 6 may be composed of a combination of a plurality of particles having different average particle diameters.

The content of the particles (6) is preferably less than 0.3% by weight based on the solid content of the binder resin (5). The lower limit is preferably 0.05% by weight or more, and more preferably 0.075% by weight or more. When the content of the particles with respect to the solid content of the resin is 0.05 wt% or more, the watermark prevention property and the anti-Newton ring property can be obtained. When the content is less than 0.3 wt%, the haze and the high light ray transmittance required for the inner attachment sheet can be achieved.

The hard coat layer 2 of the present embodiment can be formed by applying a curable composition containing a resin and particles before curing onto a substrate 4, drying and irradiating it with ionizing radiation. Additives such as a leveling agent, an ultraviolet absorber, and an antioxidant may be added to the above-mentioned curable composition.

The thickness of the hard coat layer 2 is preferably 0.5 占 퐉 or more, more preferably 1 占 퐉 or more, preferably 10 占 퐉 or less, more preferably 5 占 퐉 or less, particularly preferably 3 占 퐉 or less.

Next, the shape and optical characteristics of the hard coat layer 2 will be described.

The surface of the hard coat layer 2 composed of the resin and the particles described above is formed with convex portions due to particles. When the particle size and the content of the particles are in a specific range, the area excluding the convex portions (flat portion area) is 98% Is adjusted to be less than 100%. In a state where the flat area is 98% or more and less than 100%, the convex portions adjacent to each other on the surface of the hard coat layer hardly adhere to each other and are dispersed sparsely. The distance between the convex portion and the convex portion closest to the convex portion is, for example, on the order of several to several tens of times the convex portion radius. By this state, the effect of preventing Newton rings can be enhanced as compared with the case where fine convex portions are present on one surface. Further, since the convex portions are dotted, there is no case in which a so-called watermark is generated by pressing evenly on a flat surface, for example, a surface (glass surface or a deflection plate) of a display device.

The flat surface area referred to herein is obtained by photographing the surface of the anti-scattering sheet of the present embodiment with a CCD camera at a magnification of 100 and from the data obtained by binarizing (image processing) the image. Specifically, in the case of a binary image, the convex portion is drawn in white, and the flat portion is drawn in black. The black area is calculated with respect to the reference area (for example, 6.3 mm 2), and the ratio of the black area to the reference area is determined to be the flat area.

Since the convex portions in the scattering-prevention sheet of the present embodiment exist in a sparse state as described above, even if relatively large particles (for example, particles having an average particle size of 5 mu m) are used, the haze is not increased and a high total light transmittance . The haze (JIS K7136: 2000) as the inner adhesive sheet is preferably 2.0% or less, more preferably 1.0% or less. It is possible to maintain an appropriate haze by adjusting the content thereof according to the average particle size of the particles.

Regarding the shape of the convex portion, as described above, the hard coat layer of the present embodiment has no "wave" by using an ionizing radiation curable resin containing a specific resin A as the resin constituting it, The ratio of the height of the convex portion (referred to as aspect ratio) is a relatively large convex portion. Specifically, the aspect ratio is 0.043 or more. If the aspect ratio of the convex portion 8 is out of this range, it is difficult to obtain the effect of preventing sparkle due to suppression of wave generation while maintaining the coating film strength.

The aspect ratio of the convex portion is preferably 0.2 or less, more preferably 0.18 or less, and still more preferably 0.16 or less from the viewpoint of preventing the coating film surface particles 6 from falling off.

The "aspect ratio of the convex portion" means a ratio (H / L) to the bottom length L of the height H of the convex portion 8 (all refer to FIG. 3). Here, the "convex portion 8" means a portion where the particles 6 protrude from the surface of the coating film (hard coat layer 2), and the height (the height of the convex portion 8) (탆) of the tangent line on the smooth part of the coating film on which the coating film does not exist and the tangent line to the upper part of the convex part 8. Refers to the bottom face of a circular area having a gradient of 0.1 mu m in height of the coat portion contacting with the periphery of the convex portion 8 when the convex portion 8 is viewed from a plane, and the length (bottom length) (L ) Denotes the diameter (mu m) of the bottom surface of the circular area.

In the present embodiment, the height H of the convex portion 8 is preferably 0.3 占 퐉 or more, and more preferably 0.4 占 퐉 or more, in consideration of the anti-Newton ring property. On the other hand, it is preferably 8 占 퐉 or less, more preferably 6 占 퐉 or less, from the viewpoint of preventing the coating film surface particles 6 from coming off.

In the present embodiment, the bottom length L is preferably 80 占 퐉 or less, more preferably 60 占 퐉 or less, further preferably 40 占 퐉 or less, and most preferably 37 占 퐉 or less, in consideration of spark- . On the other hand, it is preferably not less than 3 탆, more preferably not less than 4 탆, from the viewpoint of both anti-Newton ring property and anti-sparkle property.

In the present embodiment, the height H and the bottom length L of the convex portion 8 can be obtained from the cross-sectional shape of the coating film photographed using, for example, a confocal laser microscope (VK-9710, manufactured by Keyence Corporation) . Dimensional information of the coating film surface shape measured by using various apparatuses such as a confocal microscope, an interference microscope, and an atomic force microscope (AFM).

The hard coat layer 2 has a surface hardness such that scratches do not occur even if the steel wool # 0000 is reciprocated 5 times (preferably 10 times) or more by a load of 200 g / 2 cm 2 from the viewpoint of preventing scratches desirable. Particularly, in the present embodiment, since the photopolymerizable unsaturated group is introduced into the thermoplastic resin / thermosetting resin to be combined with the ionizing radiation curable resin, the number of reciprocations by the steel wool # 0000 on the surface of the hard coat layer 2 is increased to 10 times or more It is possible to do.

In the case where the scattering-prevention sheet of the present embodiment includes the adhesive layer 3 (Fig. 2), the same adhesive agent as the adhesive agent for bonding the display device and the touch panel may be used as the adhesive layer.

Although the scattering-prevention sheet of the present invention has been described above as an example of the scattering-prevention sheet having the structure shown in Fig. 2, the present invention is not limited to the structure of Fig. 2, It is also possible to add elements, and these anti-scattering sheets are also included in the present invention.

Next, an application example of the anti-scattering sheet of the present embodiment will be described. The light-scattering-prevention sheet of the present embodiment can be applied to various display apparatuses as long as it is a display apparatus having a surface disposed in opposition to the inside. As a typical application example, a display apparatus with capacitive touch panel using the shake- .

1, the capacitive touch panel-attached display device 35 is mainly composed of a capacitive touch panel 32 with a scattering-prevention sheet 1 on the display device 34 as an optical adhesive (OCA: Optically Clear Adhesive (33). The anti-scattering sheet 1 is disposed on the opposite side of the touch surface 31 of the capacitive touch panel 32, and the hard coat layer 2 of the anti-scattering sheet 1 faces the display device 34 have. The capacitive touch panel-attached display device 35 fixes only the outer edge portion of the capacitive touch panel 32 to the display device 34 by using the optical adhesive 33. [

Examples of the display device 34 include a liquid crystal display device, a CRT display device, a plasma display device, and an EL display device.

The capacitance type touch panel 32 may be a conventionally known capacitance type touch panel, and a capacitance type touch panel having a surface type structure or a projection type structure may be used.

The optical pressure sensitive adhesive 33 may be a known pressure sensitive adhesive used for optical use of the capacitive touch panel 32. For example, a natural pressure sensitive adhesive, a synthetic rubber pressure sensitive adhesive, an acrylic pressure sensitive adhesive, a urethane pressure sensitive adhesive or a silicone pressure sensitive adhesive . The pressure-sensitive adhesive may be a solvent-based, solvent-based, emulsion-based or aqueous-based adhesive. Among them, an acrylic pressure-sensitive adhesive, particularly a solvent-based pressure-sensitive adhesive, is preferable from the viewpoint of transparency, weather resistance, durability or cost.

1 shows a surface structure in which only the outer edge portion of the capacitive touch panel 32 is fixed to the display device 34 by the optical adhesive 33. The front surface of the capacitive touch panel 32 is connected to the display device 34) bonded to each other.

Further, the scattering-prevention sheet of the present embodiment can be used in any of a large-sized or small-sized display device.

Example

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in more detail with reference to embodiments. In the following examples, " part " and "% " are by weight unless otherwise indicated.

1. Synthesis of Resin A

150 parts by weight of methyl isobutyl ketone as a solvent was supplied to the reaction vessel and heated to 90 DEG C and maintained. 61 parts by weight of methyl methacrylate, 26 parts by weight of glycidyl methacrylate, and 1.5 parts by weight of azobis-2-methylbutyronitrile as a radical polymerization initiator were slowly added dropwise to the reaction vessel over 2 hours, Time left. Thereafter, the mixture was heated at 120 DEG C for 1 hour to carry out a polymerization reaction to obtain a polymer.

Next, after cooling the polymer to 60 占 폚, 13 parts by weight of acrylic acid, 0.05 part by weight of para-methoxyphenol as a polymerization inhibitor and 0.5 part by weight of triphenylphosphine as a catalyst were mixed with the polymer to obtain a mixture. Thereafter, the mixture was heated to 110 DEG C for 8 hours, and acrylic acid was added to the polymer. As a result, Resin A (40% non-volatile component) having an acryloyl group (photo-curable unsaturated group) introduced into the thermosetting resin was prepared. The resin A had a glass transition point of 86 占 폚 and a weight average molecular weight of 80,000.

2. Fabrication of shatterproof sheet

[Example 1]

A coating liquid of the following formulation was applied to one side of a transparent polyester film (Cosmo Shine A4350: Toyo Boseki Co., Ltd.) having a thickness of 125 占 퐉, dried and irradiated with ultraviolet rays to form a hard coat layer having a thickness of 3 占 퐉, Of the anti-scattering sheet.

≪ Coating liquid for hard coat layer >

· Ionizing radiation curable resin (solid content 80%) 125 parts

(Unidick 17-813: DIC)

Resin A (solid content 40%) 97.2 parts

· Photopolymerization initiator 3 parts

(Irgacure 184: Chiba, Japan company)

0.07 part of acrylic resin particles

(MX-180TA: an average particle size of 1.8 占 퐉, manufactured by Soken Chemical & Engineering Co., Ltd.)

Diluent 478 parts

Further, in Example 1, the ratio of the hard coat layer of the acrylic resin particles to the total resin solid content was 0.05 wt%. In Example 1 and the following Examples 2 to 7 and Comparative Examples 1 and 2, the ratio of the resin A to the total resin was 28 wt%.

[Example 2]

The anti-scattering sheet of Example 2 was obtained in the same manner as in Example 1, except that the content of the acrylic resin particles in the coating liquid for hard coat layer in Example 1 was changed to 0.14 parts (0.1 wt%).

[Example 3]

The procedure of Example 1 was repeated except that the acrylic resin particles in the coating solution for hard coat layer were changed to acrylic resin particles (MX-300, manufactured by Soken Chemical & Engineering Co., Ltd., average particle size 3 탆) having different average particle diameters To obtain the anti-scattering sheet of Example 3.

[Example 4]

A shatterproof sheet of Example 4 was obtained in the same manner as in Example 3 except that the content of the acrylic resin particles in the coating solution for hard coat layer of Example 3 was changed to 0.14 parts (0.1 wt%).

[Comparative Example 1]

The anti-scattering sheet of Comparative Example 1 was obtained in the same manner as in Example 3, except that the content of the acrylic resin particles in the coating solution for hard coat layer of Example 3 was changed to 0.42 part (0.3% by weight).

[Example 5]

The procedure of Example 1 was repeated except that the acrylic resin particles in the coating solution for hard coat layer were changed to acrylic resin particles (MX-500, manufactured by Soken Chemical & Engineering Co., Ltd., average particle diameter 5 탆) having different average particle diameters To obtain the anti-scattering sheet of Example 5.

[Example 6]

The anti-scattering sheet of Example 6 was obtained in the same manner as in Example 5, except that the content of the acrylic resin particles in the coating solution for hard coat layer in Example 5 was changed to 0.14 parts (0.1 wt%).

[Comparative Example 2]

The anti-scattering sheet of Comparative Example 2 was obtained in the same manner as in Example 5, except that the content of the acrylic resin particles in the coating solution for hard coat layer in Example 5 was changed to 0.42 part (0.3% by weight).

[Comparative Example 3]

The anti-scattering sheet of Comparative Example 3 was obtained in the same manner as in Example 1 except that the coating solution for hard coat layer of Example 1 was changed to the following formulation.

≪ Coating liquid for hard coat layer >

· Ionizing radiation curable resin (solid content 80%) 125 parts

(Unidick 17-813: DIC)

Resin A (40% solids) 27.8 parts

· Photopolymerization initiator 3 parts

(Irgacure 184: Chiba, Japan company)

0.07 part of acrylic resin particles

(MX-300, manufactured by Soken Chemical & Engineering Co., average particle diameter: 3 mu m)

Diluent 478 parts

The ratio of the resin A to the total resin in Comparative Example 3 was 10% by weight.

[Comparative Example 4]

The anti-scattering sheet of Comparative Example 4 was obtained in the same manner as in Example 1, except that the acrylic resin particles in the coating liquid for hard coat layer of Example 1 were excluded.

[Comparative Example 5]

The acrylic resin particles in the coating solution for hard coat layer of Example 1 were formed into a colloidal silica dispersion (SIRMIBK (solid content: 30%): CIK Nanotech Co., colloidal silica having an average particle diameter of 0.1 占 퐉) having different average particle diameters The shatterproof sheet of Comparative Example 5 was obtained in the same manner as in Example 1 except that the content was changed to 153 parts (33% by weight).

Details of the resin and particles used in Examples and Comparative Examples are summarized in Table 1.

3. Evaluation

The following evaluation was made on the anti-scattering sheet obtained by each of the Examples and Comparative Examples.

(1) Number of particles, convex area ratio and flat area area ratio

The surface of each shrinkage preventing sheet was photographed at a magnification of 100 at a magnification of 100 using a digital microscope VHX-100 (manufactured by Keans), and an image was taken in a two-dimensional image analysis software WinROOF (manufactured by Mitani Co.) (Binary Evolution Valley Method). The areas of the white portion and the black portion in the monochrome image after the treatment were calculated to obtain the convex area and the flat area, respectively.

The convex area was calculated by dividing the obtained convex area by a measuring range of 6.3 mm < 2 >. The flat area ratio was calculated by subtracting the convex area ratio calculated from 100%.

(2) Arithmetic mean roughness

The arithmetic mean roughness of the uneven surface of the shatterproof sheet was measured using an atomic force microscope (Nanocute system manufactured by Hitachi High-Tech Science Co., Ltd., standard: JIS B0601: 2001, probe: Si single crystal probe, measurement mode: DFM mode, Treatment (XY) once).

100 mu m x 100 mu m of each of the scattering-preventive sheets was observed with an atomic force microscope, and 10 mu m x 10 mu m was set as a measurement area of the convexity portion around the point having the convexity, and 10 mu m占 10 占 퐉 as the measurement area of the flat part, and the arithmetic average roughness was obtained for each measurement area.

In Comparative Example 5, fine convex portions were formed almost uniformly all over the surface, and an area with convex portions and an area with concave portions could not be divided in the above-mentioned measurement area. Therefore, the measurement area (10 占 퐉 占 10 占 퐉) Respectively.

(3) Sparkle

Size: 3 inches, resolution: 480 x 854 dpi After the display screen of the wide VGA liquid crystal display device was displayed in green, each scattering prevention sheet was placed on the display screen and the liquid crystal display screen was observed with the naked eye. As a result, it was determined that the sparkle was not visually observed at all, "? &Quot;, the sparkle was slightly visually observed but the no sparkle was observed "

(4) Newton ring prevention property

Each shatterproof sheet was placed on a smooth glass plate so that the concave and convex surfaces were in close contact with each other, and pressed firmly with a finger to visually confirm the occurrence of the Newton ring. As a result, "Newton ring" was shown as "○" and Newton ring was shown as "×".

(5) Watermark

A sample piece having a length of 3 cm and a length of 3 cm was cut out from each shatterproof sheet, and each sample piece was placed on a glass plate whose surface was smooth, so that the concave and convex surfaces were in contact with each other. Silicone rubber cube (size: 2.5 mm in height) was placed at four corners of a scattering-prevention sheet (sample piece), and a glass plate was placed thereon and a weighing scale (weight: 1 kg) Was applied. After heating for 10 minutes at 110 DEG C in this state, the occurrence of a watermark was visually confirmed.

, &Quot;? &Quot;, "? &Quot;, and " x ", respectively.

The evaluation results are summarized in Table 2.

As can be seen from the results shown in Table 2, the amount of particles in the hard coat layer using the specific resin A was less than 0.3 wt% of the resin solid content, and the area ratio of the flat part was 98% Shrinkage preventing sheet excellent in anti-Newton ring property and anti-adhesion property is provided.

1 ... scattering prevention sheet, 2 ... hard coat layer, 5 ... binder resin, 6 ... particle, 8 ... convex portion, 31 ... touch surface, 32 ... capacitive type A touch panel, 34 ... display device, 35 ... a capacitive touch panel display device.

Claims (6)

A scatter preventive sheet comprising a plurality of convex portions due to the particles on a surface thereof and having a layer containing a particle and a resin and being adhered to (adhered to) a surface of the member constituting the display device,
The particles have an average particle size of 0.5 to 10 mu m and a content of less than 0.3 wt% of the resin solid constituting the layer,
Wherein the resin comprises a compound having a photopolymerizable unsaturated group introduced into a thermoplastic resin or a thermosetting resin and having a weight average molecular weight of 70,000 or more and a glass transition temperature of 45 ° C or higher in an amount of not less than 15% Wherein the curable resin is a curable resin. The anti-scattering sheet according to claim 1,
Wherein an area of a flat region without a convexity caused by the particles is 98% or more. The anti-scattering sheet according to claim 1,
And a haze (JIS K7136: 2000) of 2.0% or less. The anti-scattering sheet according to claim 1,
And the aspect ratio of the convex portion is 0.043 to 0.2. The anti-scattering sheet according to claim 1,
And the height of the convex portion is 0.3 to 8 占 퐉. The anti-scattering sheet according to claim 1,
Wherein the convex portion has a bottom length of 3 to 80 占 퐉.

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