JP2013020120A - Hard coat film and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coat film capable of effectively preventing scattering of broken pieces or the like even when a glass substrate or the like is broken, and to provide a touch panel using the same.SOLUTION: In the hard coat film which has a transparent substrate layer, a hard coat layer stacked in one face side of the substrate layer, and an adhesive layer stacked in the other face side of the substrate layer, an in-plane retardation value (Ro) is 100 nm or less, and a retardation value in a thickness direction (Rth) is 200 nm or less. In the hard coat film, the substrate layer contains a polycarbonate-based resin, a cycloolefin copolymer or an acrylic resin as a main component. The hard coat film has an average thickness of the substrate layer of 10 μm or more and 500 μm or less. The hard coat film has a haze value of 2% or less.

Description

  The present invention relates to a hard coat film and a touch panel suitably used for a liquid crystal display device.

  Liquid crystal display modules (LCDs) are widely used as flat panel displays taking advantage of their features such as thinness, light weight, and low power consumption, and their applications are information on mobile phones, personal digital assistants (PDAs), personal computers, televisions, etc. It is expanding year after year as a display device. In recent years, characteristics required for liquid crystal display modules vary depending on applications, but include bright (higher brightness), easier viewing (wider viewing angle), energy saving, thinner and lighter, larger screen, and the like.

  As such a liquid crystal display module, there is a liquid crystal display module on which a touch panel is mounted in order to improve the operability and quickness of the viewer. A liquid crystal display module equipped with such a touch panel generally has a structure in which a touch panel, a liquid crystal display element, various optical sheets, and a backlight are superimposed in this order from the front surface side to the back surface side. Yes.

  As such a touch panel, there are an electrostatic capacity method, a resistance film method, an electromagnetic induction method, and the like. As such a capacitance method, an electrode is extended in a direction intersecting each other, and when the finger or the like comes into contact, the capacitance between the electrodes is detected to detect the input position. (Refer to JP 2011-76386 A), by applying alternating current of the same phase and the same potential to both ends of the translucent conductive film, and detecting the weak current that flows when the capacitor is formed in contact with or close to the finger. There is something that detects the input position.

  However, when such a touch panel is pressed down or dropped by the viewer, the glass substrate or the like may be damaged and the fragments may be scattered. In such a touch panel, when a glass substrate or the like scatters, there is a risk that these fragments will pierce the viewer's fingers and the like and the viewer may be injured, and these fragments are superposed on the back side of the touch panel. There is a problem that the display element or the like may be damaged. Such a problem also exists in other types of touch panels such as a resistive film type and an electromagnetic induction type.

JP 2011-76386 A

  The present invention has been made in view of such circumstances, and even when a glass substrate or the like is broken, a hard coat film that can effectively prevent the fragments and the like from scattering and a touch panel using the hard coat film. It is intended to provide.

The invention made to solve the above problems is
A transparent substrate layer;
A hard coat layer laminated on one surface side of the base material layer;
Having an adhesive layer laminated on the other surface side of the base material layer,
The hard coat film has an in-plane retardation value (Ro) of 100 nm or less and a thickness direction retardation value (Rth) of 200 nm or less.

  Since the hard coat film is provided with a base material layer, a hard coat layer and an adhesive layer, even if this glass substrate or the like is damaged by sticking to the glass substrate or the like of the touch panel by this adhesive layer, These pieces can be effectively prevented from scattering. In addition, since the hard coat film has a hard coat layer laminated on one side of the base material layer, it can enhance the function of preventing damage during manufacturing or transportation of touch panels, etc. Can be improved. Since the inner surface retardation value (Ro) and the thickness direction retardation value (Rth) of the hard coat film are in a predetermined range, it is possible to prevent the optical function of other optical members from being hindered. The hard coat film may be used in a three-dimensional display device. When the hard coat film is used in a stereoscopic image display device, it can suppress a rainbow pattern when viewed with polarized sunglasses.

  In the hard coat film, the base material layer preferably contains a polycarbonate resin, a cycloolefin copolymer, or an acrylic resin as a main component. Thereby, the inner surface retardation value (Ro) and the thickness direction retardation value (Rth) can be easily reduced. Moreover, the said hard coat film can improve impact resistance because the said base material layer has a polycarbonate-type resin as a main component. In the hard coat film, since the base material layer is mainly composed of a cycloolefin copolymer, it can suppress a change in phase difference caused by an external force such as direct sunlight or heat generated from a display, and has excellent optical uniformity. Fine video display can be performed.

  In the hard coat film, the average thickness of the base material layer is preferably 10 μm or more and 500 μm or less. The hard coat film has an average thickness of the base material layer within the above range, thereby improving the properties of the film, such as the strength of the film and the anti-bending property, while suppressing the decrease in luminance of the liquid crystal display device. It is possible to effectively exert a function of preventing scattering of fragments generated when the glass substrate is broken.

  The hard coat film may have a haze value of 2% or less. In this way, by setting the haze value in the above range, it is possible to suppress a decrease in the visibility of the video and maintain the sharpness of the displayed video.

  The hard coat film may have a visible light transmittance of 87% or more. Thus, by making visible light transmittance into the above range, visible light can be sufficiently transmitted and visibility can be improved.

  The said hard coat film is good to be stuck by the surface and / or back surface of the glass substrate of a touch panel with the said adhesion layer. Thereby, the function of preventing scattering of fragments generated when the glass substrate is broken can be effectively enhanced.

Another invention made to solve the above problems is as follows:
It is a touch panel provided with a glass substrate and the said hard coat film stuck by the adhesion layer on the surface and / or back surface of this glass substrate.

  Since the hard coat film includes a base material layer, a hard coat layer, and an adhesive layer, by sticking the adhesive layer to the back surface of the glass substrate, even when the glass substrate is damaged, These pieces can be effectively prevented from scattering. In addition, the touch panel has a hard coat layer laminated on one side of the base layer of the hard coat film, so it can improve the damage prevention function during manufacturing and transportation, and also improve ease of handling. Can be made. Since the inner surface retardation value (Ro) and the thickness direction retardation value (Rth) of the hard coat film are in a predetermined range, the touch panel can prevent the possibility of hindering the optical functions of other optical members. it can.

  In the present invention, “in-plane retardation value (Ro)” is a value obtained by Ro = (Ny−Nx) × d, and “thickness direction retardation value (Rth)” is Rth = ((Nx + Ny). ) / 2−Nz) × d. Here, Nx is the refractive index of the fast axis of the film (axis parallel to the plane direction), and Ny is the refractive index of the slow axis of the film (axis parallel to the plane direction and perpendicular to the fast axis). Nz is the refractive index of the film in the thickness direction (direction perpendicular to the surface direction), and d is the thickness of the film.

  The “haze value” is a value according to JIS K7136. “Visible light transmittance” is a value according to JIS K7361-1.

  As described above, the hard coat film of the present invention and the touch panel using the same can effectively prevent the fragments and the like from scattering even when the glass substrate or the like is damaged.

It is a typical sectional view showing the hard coat film concerning one embodiment of the present invention. It is typical sectional drawing which shows the touchscreen which concerns on one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate.

  The hard coat film 1 in FIG. 1 has a base material layer 2, a hard coat layer 3, and an adhesive layer 4. The hard coat film 1 is laminated on a glass substrate by attaching an adhesive layer 4 to the front surface and / or back surface of the glass substrate of the touch panel in a liquid crystal display device equipped with a touch panel.

  Since the base material layer 2 needs to transmit light, the base material layer 2 is formed to be transparent, particularly colorless and transparent. Although the main component which comprises the base material layer 2 is not specifically limited, Typically, it selects from the group which consists of polycarbonate-type resin, cycloolefin-type resin, acrylic resin, polypropylene-type resin, and polyethylene terephthalate-type resin. These synthetic resins have excellent optical transparency and can transmit light rays well. Especially, as a main component which comprises the base material layer 2, polycarbonate-type resin, a cycloolefin copolymer, or acrylic resin is preferable. By using a polycarbonate resin, a cycloolefin copolymer or an acrylic resin as the main component constituting the base material layer 2, the inner surface retardation value (Ro) and the thickness direction retardation value (Rth) of the hard coat film 1 can be easily obtained. Can be made smaller. Polycarbonate resins have excellent impact resistance. As a result, the hard coat film 1 can improve impact resistance by using a polycarbonate-based resin as a main component, and as a result, can further improve the prevention of scattering of fragments such as a glass substrate. Cycloolefin copolymers have a low photoelastic coefficient. As a result, the hard coat film 1 has a cycloolefin copolymer as a main component, so that the retardation value can be reduced and a change in phase difference caused by an external force such as direct sunlight or heat generation of the display can be suppressed. Excellent uniformity and fine video display.

  The base material layer 2 may contain other optional components as long as the transparency and the desired strength are not impaired, but preferably contains 90% by mass or more, more preferably 98% by mass or more of the main component made of the above synthetic resin. Including. Examples of optional components here include ultraviolet absorbers, stabilizers, lubricants, processing aids, plasticizers, impact resistance aids, retardation reducing agents, matting agents, antibacterial agents, and fungicides.

  The polycarbonate resin forming the base material layer 2 is not particularly limited, and may be either a linear polycarbonate resin or a branched polycarbonate resin, but a linear polycarbonate resin and a branched polycarbonate resin A polycarbonate-based resin made of

  The linear polycarbonate-based resin is a linear aromatic polycarbonate-based resin produced by a known phosgene method or melting method, and includes a carbonate component and a diphenol component. Examples of the precursor for introducing the carbonate component include phosgene and diphenyl carbonate. Examples of the diphenol include 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, and 1,1-bis (4-hydroxy). Phenyl) cyclohexane, 1,1-bis (3,5-dimesyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) decane, 1,1-bis (4-hydroxyphenyl) propane, , 1-bis (4-hydroxyphenyl) cyclodecane, 1,1-bis (3,5-dimethyl-4-hydroxyphenyl) cyclododecane, 4,4′-dihydroxydiphenyl ether, 4,4′-thiodiphenol, 4 , 4'-dihydroxy-3,3-dichlorodiphenyl ether and the like. These can be used alone or in combination of two or more. Such a linear polycarbonate resin is produced by, for example, the method described in US Pat. No. 3,998,672, and preferably has a refractive index of 1.57 or more and 1.59 or less.

  The branched polycarbonate resin is a polycarbonate resin produced using a branching agent. Examples of the branching agent include phloroglucin, trimellitic acid, 1,1,1-tris (4-hydroxyphenyl) ethane, 1, 1,2-tris (4-hydroxyphenyl) ethane, 1,1,2-tris (4-hydroxyphenyl) propane, 1,1,1-tris (4-hydroxyphenyl) methane, 1,1,1-tris (4-hydroxyphenyl) propane, 1,1,1-tris (2-methyl-4-hydroxyphenyl) methane, 1,1,1-tris (2-methyl-4-hydroxyphenyl) ethane, 1,1, 1-tris (3-methyl-4-hydroxyphenyl) methane, 1,1,1-tris (3-methyl-4-hydroxyphenyl) ethane, 1,1-tris (3,5-dimethyl-4-hydroxyphenyl) methane, 1,1,1-tris (3,5-dimethyl-4-hydroxyphenyl) ethane, 1,1,1-tris (3- Chloro-4-hydroxyphenyl) methane, 1,1,1-tris (3-chloro-4-hydroxyphenyl) ethane, 1,1,1-tris (3,5-dichloro-4-hydroxyphenyl) methane, , 1,1-tris (3,5-dichloro-4-hydroxyphenyl) ethane, 1,1,1-tris (3-bromo-4-hydroxyphenyl) methane, 1,1,1-tris (3-bromo -4-hydroxyphenyl) ethane, 1,1,1-tris (3,5-dibromo-4-hydroxyphenyl) methane, 1,1,1-tris (3,5-dibromo-4-hydroxyphenyl) Tan, 4,4'-dihydroxy-2,5-dihydroxydiphenyl ether, and the like.

  Such branched polycarbonate resins include, for example, aromatic diphenols, polycarbonate oligomers derived from the above branching agents and phosgene, aromatic diphenols, and the like, as described in JP-A No. 03-182524. A method in which an end stop agent is reacted while stirring so that the reaction mixture containing these becomes a turbulent flow, and when the viscosity of the reaction mixture rises, an aqueous alkali solution is added and the reaction mixture is reacted as a laminar flow. Can be manufactured. The branched polycarbonate resin of the resin composition of the present invention is contained in the polycarbonate resin in the range of 5 wt% to 80 wt%, preferably in the range of 10 wt% to 60 wt%. This is because if the branched polycarbonate resin is less than 10% by weight, the elongational viscosity decreases and molding by extrusion molding becomes difficult, and if it exceeds 80% by weight, the shear viscosity of the resin increases and the molding processability decreases. It is to do.

  The cycloolefin copolymer forming the base material layer 2 refers to an amorphous cyclic olefin resin that is a copolymer of a cyclic olefin and an olefin such as ethylene. As the cyclic olefin, there are a polycyclic cyclic olefin and a monocyclic cyclic olefin. Such polycyclic olefins include norbornene, methylnorbornene, dimethylnorbornene, ethylnorbornene, ethylidenenorbornene, butylnorbornene, dicyclopentadiene, dihydrodicyclopentadiene, methyldicyclopentadiene, dimethyldicyclopentadiene, tetracyclododecene. , Methyltetracyclododecene, dimethylcyclotetradodecene, tricyclopentadiene, tetracyclopentadiene, and the like. Examples of the monocyclic olefin include cyclobutene, cyclopentene, cyclooctene, cyclooctadiene, cyclooctatriene, and cyclododecatriene.

The photoelastic coefficient of the cycloolefin copolymer is not particularly limited, but is, for example, 10 × 10 ⁻¹² / Pa or less, preferably 9 × 10 ⁻¹² / Pa or less, particularly preferably 8 × 10 ⁻¹² / Pa or less. . If the photoelastic coefficient of the cycloolefin copolymer exceeds the above range, the change in the phase difference when exposed to high temperature and high humidity becomes large, and the visibility may be lowered. On the other hand, when the photoelastic coefficient of the optical film 1 is within the above range, it is possible to reduce a change in phase difference when exposed to high temperature and high humidity, thereby suppressing a decrease in the visibility of the screen. Image display can be performed.

Incidentally, "photoelastic coefficient" is a coefficient representing the resulting ease of change in refractive index due to external force is a value determined by _{C R [/ Pa] = Δn} / σ R. Here, σ _R is an extensional stress [Pa], Δn is a refractive index when stress is applied, and Δn is defined by the following equation.
Δn = n ₁ −n ₂
(Where n ₁ is the refractive index in the direction parallel to the tensile stress, and n ₂ is the refractive index in the direction perpendicular to the tensile direction.)

  The acrylic resin forming the base material layer 2 is a resin having a skeleton derived from acrylic acid or methacrylic acid. Examples of acrylic resins include, but are not limited to, poly (meth) acrylic acid esters such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymers, and methyl methacrylate- (meth) acrylic acid esters. Copolymer, methyl methacrylate-acrylic ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer, polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate- Cyclohexyl methacrylate copolymer, methyl methacrylate- (meth) acrylate norbornyl copolymer), and the like. Among these acrylic resins, poly (meth) acrylic acid C1-6 alkyl such as poly (meth) methyl acrylate is preferable, and methyl methacrylate resin is more preferable.

  The polypropylene resin forming the base material layer 2 is a resin having a skeleton derived from propylene. Although it does not specifically limit as an example of a polypropylene resin, Copolymer of propylene homopolymer or propylene, and 1 or more types of monomers selected from the group which consists of ethylene and a C4-C12 alpha olefin. A polymer etc. are mentioned.

  The polyethylene terephthalate resin forming the base material layer 2 is a polymer obtained by the reaction of terephthalic acid and ethylene glycol. The polyethylene terephthalate-based resin may contain other comonomers, but those having a repeating unit of polyethylene terephthalate of 80 mol% or more are preferable. Polyethylene terephthalate is prepared by, for example, charging dimethyl terephthalate and ethylene glycol into a reactor, performing an ester exchange reaction while gradually raising the internal temperature, then transferring the reaction product to the polymerization reactor, and performing a polymerization reaction under high temperature vacuum Can be generated.

  Although the thickness (average thickness) of the base material layer 2 is not specifically limited, For example, 10 micrometers or more and 500 micrometers or less are preferable, 20 micrometers or more and 300 micrometers or less are more preferable, and 25 micrometers or more and 125 micrometers or less are especially preferable. When the thickness of the base material layer 2 is less than the above range, characteristics such as film strength and anti-bending property are deteriorated, and there is a possibility that a function of preventing the scattering of fragments generated when the glass substrate of the touch panel is broken or the like may be deteriorated. Moreover, when the thickness of the base material layer 2 exceeds the above range, the luminance of the liquid crystal display device may be lowered, and it also goes against the demand for thinning the liquid crystal display device. On the other hand, the hard coat film 1 has an average thickness of the base material layer within the above range to improve the properties such as the strength of the film and the anti-bending property while suppressing a decrease in the luminance of the liquid crystal display device. In addition, it is possible to effectively exhibit a function of preventing fragments from being scattered when the glass substrate of the touch panel is damaged.

  As the base material layer 2, one having an arithmetic average surface roughness (Ra) of 0.02 or more and 0.06 or less can be used. Further, the base material layer 2 can be subjected to a mat treatment as necessary. The arithmetic average surface roughness (Ra) of the base material layer 2 subjected to such a mat treatment is preferably 0.07 or more and 2 or less, more preferably 0.1 or more and 1 or less. By controlling the surface roughness of the base material layer 2 in such a range, scratches in the processing after the film raw fabric is manufactured are prevented, and the handleability is improved. Moreover, generally, when winding up the manufactured film original fabric, it is necessary to prevent blocking by embossing (knurling) both ends in the width direction of the film. When a knurling process is performed on a film, the processing points at both ends of the film cannot be used, so that part must be cut and discarded. In the film winding operation, masking may be performed with a protective film in order to prevent damage. However, by making the arithmetic average surface roughness of the base material layer 2 within the predetermined range as described above, blocking can be prevented without performing a knurling treatment, so that the manufacturing process is simplified, and the film width direction Both end portions of the film can be used, and the film can be wound over a long length without causing a film failure. Moreover, when the base material layer 2 has moderate surface roughness, the damage at the time of winding is suppressed effectively, and the above masking is also unnecessary.

  The method for producing the base material layer 2 is not particularly limited. For example, additives such as a synthetic resin flake raw material and a plasticizer are mixed by a conventionally known mixing method to obtain a thermoplastic resin composition in advance. 2 can be manufactured. This thermoplastic resin composition can be obtained, for example, by pre-blending with a mixer such as an omni mixer and then extruding and kneading the resulting mixture. In this case, the kneader used for extrusion kneading is not particularly limited, and for example, a conventionally known kneader such as an extruder such as a single screw extruder or a twin screw extruder or a pressure kneader can be used. .

  Examples of the method for forming the base material layer 2 include known methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, and a compression molding method. Among these, the solution casting method (solution casting method) and the melt extrusion method are preferable. At this time, a thermoplastic resin composition extruded and kneaded in advance may be used, or another additive such as a synthetic resin and a plasticizer is separately dissolved in a solvent to obtain a uniform mixed solution, and then a solution cast. You may use for the film forming process of a method (solution casting method) and a melt extrusion method. Moreover, in order to keep the retardation value of the base material layer 2 and the retardation value of the hard coat film 1 constant, for example, the molten resin is formed into an arc shape with a cooling roll and an endless belt maintained at a uniform temperature in the width direction. It may be sandwiched and cooled.

  Solvents used in the solution casting method (solution casting method) include, for example, chlorinated solvents such as chloroform and dichloromethane; aromatic solvents such as toluene, xylene, benzene, and mixed solvents thereof; methanol, ethanol, and isopropanol , N-butanol, 2-butanol and the like alcohol solvents; methyl cellosolve, ethyl cellosolve, butyl cellosolve, dimethylformamide, dimethyl sulfoxide, dioxane, cyclohexanone, tetrahydrofuran, acetone, methyl ethyl ketone (MEK), ethyl acetate, diethyl ether; It is done. These solvents may be used alone or in combination of two or more. Examples of the apparatus for performing the solution casting method (solution casting method) include a drum casting machine, a band casting machine, and a spin coater.

  Examples of the melt extrusion method include a T-die method and an inflation method. The molding temperature of the film during melt extrusion is preferably 150 ° C. or higher and 350 ° C. or lower, more preferably 200 ° C. or higher and 300 ° C. or lower. When film-forming by the T-die method, a T-die is attached to the tip of a known single-screw extruder or twin-screw extruder, and the film extruded into a film shape is wound to obtain a roll film. Under the present circumstances, it is also possible to set it as a uniaxial stretching process by adjusting the temperature of a winding roll suitably, and adding extending | stretching to an extrusion direction. It is also possible to add steps such as sequential biaxial stretching and simultaneous biaxial stretching by adding a step of stretching the film in a direction perpendicular to the extrusion direction.

  Although it does not specifically limit as a plasticizer, The functional group which can interact with a synthetic resin by a hydrogen bond etc. is generated so that a haze may be generated in the base material layer 2, or it may not bleed out or volatilize from the base material layer 2. It is preferable to have. Examples of such plasticizers include, but are not limited to, phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, polyhydric alcohol plasticizers. Glycolate plasticizers, citrate plasticizers, fatty acid ester plasticizers, carboxylic acid ester plasticizers, polyester plasticizers, and the like.

  The hard coat layer 3 is laminated on one surface side of the base material layer 2 to improve the hardness of the hard coat film 1. A material for forming the hard coat layer 3 is not particularly limited. The hard coat layer 3 may be formed only from a resin, and may contain silica fine particles, a polymerization initiator, and the like.

  Examples of the resin forming the hard coat layer 3 include a thermosetting resin and an active energy ray curable resin.

  The hard coat layer 3 is formed by, for example, applying a coating composition containing a polymerizable monomer or polymerizable oligomer of an active energy ray curable resin on one surface of the base material layer 2 to crosslink the polymerizable monomer or polymerizable oligomer. And / or by polymerization reaction.

  The functional group of the active energy ray-curable polymerizable monomer or polymerizable oligomer is preferably an ultraviolet ray, electron beam or radiation polymerizable functional group, and an ultraviolet polymerizable functional group is particularly preferred. Examples of the ultraviolet polymerizable functional group include ethylenically unsaturated polymerizable functional groups such as (meth) acryloyl group, vinyl group, styryl group and allyl group.

  Although it does not specifically limit as said coating composition, The thing which has an acrylic monomer or a urethane acrylate oligomer as a main component is preferable. Hard coat layer 3 can raise hardness by being formed from the composition which has these monomers or oligomers as the main ingredients. In particular, the hard coat layer 3 is particularly preferably formed from a composition containing both urethane acrylate and (meth) acrylate.

  The total content of urethane acrylate and (meth) acrylate forming the hard coat layer 3 is preferably 45% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 95% by mass or less, and 60% by mass or more and 90% by mass. % Or less is particularly preferable. If the total content of urethane acrylate and (meth) acrylate forming the hard coat layer 3 exceeds the above upper limit, the start of photopolymerization may be delayed and productivity may be lowered. Moreover, there exists a possibility that a softness | flexibility, abrasion resistance, scratch resistance, etc. may fall that the total content of the urethane acrylate and (meth) acrylate which forms the said hard-coat layer 3 is less than the said minimum. On the other hand, when the total content of urethane acrylate and (meth) acrylate forming the hard coat layer 3 is within the above range, the flexibility, wear resistance, scratch resistance, etc. are suitably maintained while improving productivity. be able to.

  The urethane acrylate is not particularly limited, and may be either a monomer or an oligomer. In addition, the number of functional groups of urethane acrylate is not particularly limited, and may be monofunctional or polyfunctional, but is preferably 2 or more and 6 or less, and preferably 2 or more and 3 or more. More preferably, it is as follows. The hard coat layer 3 can suitably maintain the balance between hardness and elongation rate by setting the number of functional groups of urethane acrylate within the above range. Urethane acrylates may be used alone or in combination of two or more.

  The elongation percentage of urethane acrylate is preferably 20% to 80%, more preferably 25% to 75%. If the elongation percentage of the urethane acrylate exceeds the above upper limit, the durability of the hard coat layer 3 may be reduced. Moreover, there exists a possibility that a crack may generate | occur | produce at the time of shaping | molding as the elongation rate of urethane acrylate is less than the said minimum. On the other hand, when the elongation percentage of the urethane acrylate is within the above range, the durability can be improved and the occurrence of cracking during molding can be prevented.

  The “elongation rate” here means a value measured according to JIS K5600.

  Although it does not specifically limit as glass transition temperature of resin formed from urethane acrylate, 40 to 100 degreeC is preferable and 40 to 80 degreeC is more preferable. When the glass transition temperature of the resin formed from urethane acrylate is within the above range, the hardness and durability of the hard coat layer 3 at room temperature can be improved.

  Although it does not specifically limit as content of the urethane acrylate which forms the hard-coat layer 3, 10 mass% or more and 90 mass% or less are preferable, 15 mass% or more and 85 mass% or less are more preferable, 20 mass% or more and 80 mass% or less. The following are particularly preferred: If the content of the urethane acrylate forming the hard coat layer 3 exceeds the above upper limit, the wear resistance and the coating film hardness may be lowered. Moreover, a softness | flexibility falls that the content of the urethane acrylate which forms the hard-coat layer 3 is less than the said minimum, and there exists a possibility that a crack will generate | occur | produce. On the other hand, if the content of the urethane acrylate forming the hard coat layer 3 is within the above range, it maintains appropriate flexibility while maintaining appropriate wear resistance and coating film hardness, and suppresses the occurrence of cracks. Can do.

  The (meth) acrylate is not particularly limited, and may be either a monomer or an oligomer. The number of functional groups of such (meth) acrylate is not particularly limited, and may be monofunctional or polyfunctional. In addition, durability can improve the hard-coat layer 3 by using (meth) acrylate more than trifunctional. The (meth) acrylate may have a molecular structure having a polar group or a low-polar molecular structure. (Meth) acrylates may be used alone or in combination of two or more.

  Examples of the polar group of (meth) acrylate include a hydroxyl group, a carboxyl group, an amino group, and an amide group.

  Examples of the (meth) acrylate containing a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth). Acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, glycerol mono (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate And (meth) acrylic acid hydroxyl group-containing esters.

  Examples of the (meth) acrylate containing a carboxyl group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, and 2- (meth) acryloyloxyethyl succinic acid. Examples include acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, and the like.

  Examples of (meth) acrylates containing amino groups include monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, and monoethylaminopropyl (meth) acrylate. And (meth) acrylic acid monoalkylamino esters.

Examples of the (meth) acrylate containing an amide group include acrylamides such as (meth) acrylamide, N-methyl (meth) acrylamide, and N-methylol (meth) acrylamide.
Examples of the (meth) acrylate having a low polar molecular structure include (meth) acrylic acid alicyclic ester or (meth) acrylic acid alkyl ester.

  Examples of such (meth) acrylic acid alicyclic esters include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentadienyl (meth) acrylate, and tricyclodecanyl. (Meth) acrylate, norbornyl (meth) acrylate, etc. are mentioned.

  Examples of the (meth) acrylic acid alkyl ester include lauryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isodecyl (meth) acrylate, benzyl (meth) acrylate, stearyl (meth) acrylate, butyl (meth) acrylate, 1,6-hexanediol acrylate may be mentioned.

  Although it does not specifically limit as content of (meth) acrylate which forms the hard-coat layer 3, 5 mass% or more and 85 mass% or less are preferable, 10 mass% or more and 80 mass% or less are more preferable, 15 mass% or more 75 A mass% or less is particularly preferred. If the content of (meth) acrylate forming the hard coat layer 3 exceeds the above upper limit, there is a high risk of cracking during molding. Moreover, there exists a possibility that abrasion resistance and coating-film hardness may fall that content of the (meth) acrylate which forms the hard-coat layer 3 is less than the said minimum. On the other hand, when the content of the (meth) acrylate forming the hard coat layer 3 is within the above range, the wear resistance and the coating film hardness are suitably maintained while maintaining appropriate flexibility and suppressing the occurrence of cracks. can do.

  Examples of the polymerization initiator include benzophenone, benzyl, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-diethoxyacetophenone, benzyldimethyl ketal, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (Methylthio) phenyl] -2-morpholinopropanone-1, 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one, bis (cyclopentadi Enyl) -bis (2,6- Fluoro-3- (pyr-1-yl) titanium, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2,4,6-trimethylbenzoyldiphenylphosphine oxide, etc. Note that these compounds may be used alone or in combination.

  Although it does not specifically limit as pencil hardness of the hard-coat layer 3, For example, H or more are preferable, 2H or more are more preferable, and 3H or more are especially preferable. If the pencil hardness of the hard coat layer 3 is less than the lower limit, the hard coat film 1 may be inferior in hardness. On the other hand, the hard coat film 1 can keep the hard coat layer 3 at a preferable hardness when the pencil hardness of the hard coat layer 3 is within the above range. Thereby, the hard coat film 1 can improve the scratch-preventing property of the hard coat layer 3, and can improve the handleability of the hard coat film 1. “Pencil hardness” refers to a value based on the pencil scratch value described in 8.4 of the test method defined in JIS K5400.

  The thickness (average thickness) of the hard coat layer 3 is not particularly limited, but can be, for example, 0.5 μm or more and 50 μm or less.

  Although the manufacturing method of the hard-coat layer 3 is not specifically limited, It can manufacture by apply | coating active energy ray hardening resin to one surface of the base material layer 2, making it dry, and irradiating active energy ray. The application method of the active energy ray curable resin is not particularly limited as long as it is a method capable of uniformly applying the active energy ray curable resin to one surface of the base material layer 2. For example, the spin coating method and the spray method are used. And various methods such as a slide coating method, a dip method, a bar coating method, a roll coater method, and a screen printing method. In manufacturing the hard coat layer 3, surface modification treatment such as plasma treatment in an inert gas atmosphere such as argon gas or nitrogen gas may be performed as a pretreatment as necessary. Further, an undercoat layer may be laminated on one surface of the base material layer 2, and the hard coat layer 3 may be laminated via the undercoat layer.

  It is laminated on the other surface side of the base material layer 2. The adhesive layer 4 can be formed using a known adhesive resin such as an acrylic resin or a urethane resin. In addition to the known adhesive resin, the adhesive layer 4 is mixed with a thermoplastic resin such as high-pressure low-density polyethylene, an elastomer such as synthetic rubber and natural rubber, an adhesion assistant such as terpene resin and petroleum resin, and the like. It may be formed by doing.

  Examples of the adhesive resin that forms the adhesive layer 4 include structural units derived from alkyl acrylate monomers having 8 to 20 carbon atoms in the alkyl group, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, and tricyclodecane (meth). An acrylic copolymer having a structural unit derived from at least one alicyclic monomer selected from acrylates and a structural unit derived from a functional group-containing monomer can be suitably used. As the alkyl acrylate monomer, 2-ethylhexyl acrylate, isooctyl acrylate, lauryl acrylate, and stearyl acrylate are preferable, and 2-ethylhexyl acrylate is particularly preferable from the viewpoint of suppressing the adhesive force and foaming from the target of adhesion. When the adhesive strength is weak, a small amount of gas component generated from the adhesion target may stay at the interface to form bubbles, which may cause a decrease in adhesiveness or appearance. As content of the structural unit derived from the said alkyl acrylate monomer, it is with respect to all the structural units which comprise an acrylic copolymer from the point which hold | maintains predetermined adhesive force, maintaining the content of another structural unit. 29.9 mass% or more and 55 mass% or less are preferable, and 35 mass% or more and 50 mass% or less are more preferable. Moreover, as said alicyclic monomer, a cyclohexyl acrylate can be used suitably from the point which suppresses foaming from adhesive force and adhesion | attachment object. As content of the structural unit derived from the said alicyclic monomer, 50 to 70 mass% is preferable with respect to all the structural units which comprise an acryl-type copolymer, and 55 to 65 mass% is preferable. Further preferred. If the content of the structural unit derived from the alicyclic monomer exceeds the above upper limit, tack may be insufficient and the adhesive strength may be reduced. On the other hand, if the content of the structural unit derived from the alicyclic monomer is less than the lower limit, foaming from the adhesion target may not be effectively prevented. Examples of the functional group-containing monomer include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and various hydroxypropyl (meth) acrylates, or unsaturated monomers having a carboxyl group, such as (meth) acrylic acid. , Crotonic acid, fumaric acid, itaconic acid, maleic acid and the like. Especially, 2-hydroxyethyl acrylate is preferable from the point which suppresses foaming from adhesive force or adhesion object. As content of the structural unit derived from the said functional group containing monomer, 0.1 to 10 mass% is preferable, and 0.5 to 5 mass% is further more preferable. When the content of the structural unit derived from the functional group-containing monomer exceeds the above upper limit, the polarity of the pressure-sensitive adhesive layer 4 increases, and the adhesive force to the low-polarity surface may be reduced. On the other hand, when the content of the structural unit derived from the functional group-containing monomer is less than the lower limit, the cohesive force of the pressure-sensitive adhesive layer 4 may be reduced, and it may be difficult to maintain the shape against the stress in the shear direction.

  Examples of a method for producing such an acrylic copolymer include a known radical polymerization method. For example, azobisisobutyronitrile, azobisisovaleronitrile, benzoyl peroxide, etc. are prepared by dissolving the above monomer in a hydrocarbon organic solvent such as toluene or xylene or an ester organic solvent such as ethyl acetate. An organic solvent solution of an acrylic copolymer can be obtained by adding a polymerization initiator and performing polymerization at about 50 to 90 ° C. for about 3 to 20 hours.

  The weight average molecular weight of the acrylic copolymer is, for example, 200,000 or more, preferably 400,000 or more and 2,000,000 or less, more preferably 500,000 or more and 1,500,000 or less. If the weight average molecular weight of the acrylic copolymer exceeds the above upper limit, polymerization during polymer synthesis may be difficult. On the other hand, when the weight average molecular weight of the acrylic copolymer is less than the lower limit, there is a high possibility that bubbles will be generated. The weight average molecular weight is a standard polystyrene conversion value measured by gel permeation chromatography.

  The glass transition temperature of the acrylic copolymer is usually −10 ° C. or lower, preferably −70 ° C. or higher and −20 ° C. or lower in order to obtain sufficient adhesive strength as an adhesive.

  The pressure-sensitive adhesive layer 4 can be laminated on the base material layer 2 by applying a pressure-sensitive adhesive solution to the other surface side of the base material layer 2 and drying it. The adhesive layer 4 can also be laminated on the base material layer 2 by applying the adhesive solution on one side of the separator in advance and drying it, and then bonding the base material layer 2 together.

  Although the thickness (average thickness) of the adhesion layer 4 is not specifically limited, For example, it can be 10 micrometers or more and 40 micrometers or less.

  The in-plane retardation value (Ro) of the hard coat film 1 is 100 nm or less, more preferably 50 nm or less, further preferably 15 nm or less, and particularly preferably 5 nm or less. Moreover, the thickness direction retardation value (Rth) of the hard coat film 1 is set to 200 nm or less, more preferably 100 nm or less, further preferably 30 nm or less, and particularly preferably 10 nm or less. In this way, the hard coat film 1 reduces the in-plane retardation value (Ro) and the thickness direction retardation value (Rth), thereby suppressing the conversion action of transmitted light, and the optical functions of other optical members. The risk of inhibiting can be prevented.

  Although it does not specifically limit as a haze value of the said hard coat film 1, 2% or less is preferable, 1% or less is more preferable, and 0.5% or less is further more preferable. When the hard coat film 1 has a haze value that exceeds the above range, the visibility of the image is lowered, and the sharpness of the displayed image may be lowered. On the other hand, the said hard coat film 1 can suppress the fall of the visibility of an image | video by keeping a haze value into the said range, and can maintain the definition of the image | video displayed.

  The visible light transmittance of the hard coat film 1 is not particularly limited, but is preferably 87% or more, and more preferably 90% or more. When the hard coat film 1 has a visible light transmittance of less than the above range, the visible light cannot be sufficiently transmitted, and visibility may be deteriorated. On the other hand, the said hard coat film 1 can fully permeate | transmit visible light by making visible light transmittance into the said range, and can improve visibility.

  The hard coat film 1 has an adhesive layer 4 adhered to the front surface and / or back surface of the glass substrate of the touch panel and is laminated on the back surface side of the glass substrate, thereby preventing scattering of broken pieces when the touch panel is broken. Can be effectively increased.

  Since the hard coat film 1 includes the base material layer 2, the hard coat layer 3, and the adhesive layer 4, the glass substrate or the like is damaged by being adhered to the glass substrate or the like of the touch panel by the adhesive layer 4. Even in this case, these pieces can be effectively prevented from scattering. In addition, since the hard coat film 1 has the hard coat layer 3 laminated on one surface of the base material layer 2, the hard coat film 1 can be improved in the function of preventing damage during manufacture or transportation of touch panels and the like. The ease can be improved. Since the inner surface retardation value (Ro) and the thickness direction retardation value (Rth) of the hard coat film 1 are in a predetermined range, it is possible to prevent the possibility of hindering the optical functions of other optical members. . The hard coat film 1 may be used in a three-dimensional display device. When the hard coat film 1 is used in a stereoscopic image display device, it can suppress a rainbow pattern when viewed with polarized sunglasses.

  The touch panel 11 in FIG. 2 includes glass substrates 12 and 14, an electrode layer 13, and the hard coat film 1. The glass substrate 12 is formed as an input region in which a substantially central region on the front side is input by a fingertip. The hard coat film 1 is laminated on the back surface of the glass substrate 12 by sticking the adhesive layer 4. The electrode layer 13 is a transparent conductive film, and the first electrode and the second electrode extend in a direction crossing each other. The electrode layer 13 is laminated on the surface side of the glass substrate 14. The hard coat film 1 is laminated on the back surface of the glass substrate 14 by sticking the adhesive layer 4. The capacitance of the touch panel 11 changes before and after the fingers touch the input area of the glass substrate 12. The touch panel 11 is configured such that the first electrode and the second electrode detect a change in capacitance and specify a touch position.

  Since the hard coat film 1 includes the base layer 2, the hard coat layer 3, and the adhesive layer 4, the touch panel 11 has a glass substrate by sticking the adhesive layer 4 to the back surfaces of the glass substrates 12 and 14. Even when 12, 14, etc. are damaged, these pieces can be effectively prevented from scattering. Moreover, since the said touch panel 11 has the hard-coat layer 3 laminated | stacked on the one surface of the base material layer 2 of the hard-coat film 1, while being able to improve the damage prevention function at the time of manufacture, transportation, etc., handling The ease can be improved. Since the inner surface retardation value (Ro) and the thickness direction retardation value (Rth) of the hard coat film 1 are in a predetermined range, the touch panel 11 prevents the possibility of hindering the optical functions of other optical members. be able to.

  In addition, the hard coat film and touch panel of this invention can be implemented in the aspect which gave various change and improvement other than the said aspect. For example, the hard coat film may be formed of two or more hard coat layers. In addition, in the hard coat film, other layers (for example, a UV absorption layer, an antistatic layer, an antireflection layer, and the like) may be laminated on the hard coat layer. In the hard coat film, a base material layer and a hard coat layer, or a base material layer and an adhesive layer may be laminated via another layer. The said hard coat film can improve the scattering prevention property of these members by sticking to various optical members besides the back surface of the glass substrate of a touch panel. The said hard coat film may be stuck on the surface side of the glass substrate of a touch panel, and may be stuck on the surface side and back surface side of a touch panel. In particular, the hard coat film is effectively attached to the back surface of the glass substrate laminated on the back surface side of the electrode layer of the touch panel, thereby effectively enhancing the damage prevention function at the time of manufacturing or transporting the touch panel. It is possible to improve the ease of handling the touch panel. The hard coat film can be used for various touch panels such as a capacitance method, a resistance film method, and an electromagnetic induction method. The hard coat film can be used for various liquid crystal display modules such as a stereoscopic video display device in addition to a touch panel.

  As described above, the hard coat film of the present invention can be suitably used for a touch panel that can effectively prevent the fragments and the like from scattering even when the glass substrate or the like is damaged.

DESCRIPTION OF SYMBOLS 1 Hard coat film 2 Base material layer 3 Hard coat layer 4 Adhesive layer 11 Touch panel 12 Glass substrate 13 Electrode layer 14 Glass substrate

Claims (9)

A transparent substrate layer;
A hard coat layer laminated on one surface side of the base material layer;
Having an adhesive layer laminated on the other surface side of the base material layer,
A hard coat film having an in-plane retardation value (Ro) of 100 nm or less and a thickness direction retardation value (Rth) of 200 nm or less.   The hard coat film according to claim 1, wherein the base material layer contains a polycarbonate-based resin as a main component.   The hard coat film according to claim 1, wherein the base material layer contains a cycloolefin copolymer as a main component.   The hard coat film according to claim 1, wherein the base material layer contains an acrylic resin as a main component.   The average thickness of the said base material layer is 10 micrometers or more and 500 micrometers or less, The hard coat film of any one of Claims 1-4.   The hard coat film according to claim 1, having a haze value of 2% or less.   The hard coat film according to any one of claims 1 to 6, which has a visible light transmittance of 87% or more.   The hard coat film according to any one of claims 1 to 7, wherein the hard coat film is attached to the front surface and / or the back surface of the glass substrate of the touch panel by the adhesive layer.   A touch panel provided with a glass substrate and the hard coat film according to any one of claims 1 to 7, which is adhered to the front surface and / or back surface of the glass substrate with an adhesive layer.

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