JP7035330B2 - Hardcourt film - Google Patents

Description

The hard coat film of the present invention is a display device such as a liquid crystal display or an organic EL display, an input device such as a touch panel, and various electric and electronic terminals of a portable electronic terminal (game device, personal computer, tablet, mobile phone, smartphone, smart glass, etc.). Regarding products.

The touch panel type image display device usually has a configuration in which a surface protection panel, a touch panel, and an image display panel (collectively, also referred to as "components for an image display device") are combined.
The surface protection panel of the touch panel type image display device such as a smartphone or tablet terminal is made of a plastic material such as an acrylic resin plate or a polycarbonate plate together with tempered glass. In the touch panel, a plastic film sensor is used together with the glass sensor, a member called a touch-on lens (TOR) whose touch panel function is integrated with the surface protection panel is used, and the touch panel function is integrated into the image display panel. Members such as on-cell and in-cell are used.

In recent years, in this type of image display device, one having a characteristic design such as a curved design of the image display device itself has been disclosed. (Patent Document 1)

Japanese Unexamined Patent Publication No. 2016-108555

When designing a hard-coated film compatible with the curved display described in Patent Document 1, it is necessary to achieve both the contradictory characteristics of surface hardness and flexibility at a high level. Further, when the member having a curved surface shape and the hard coat film are bonded to each other, the smoothness of the hard coat film is also required in order to prevent wrinkles and the like from forming in the hard coat film.

Therefore, the present invention provides a hard coat film that can achieve both surface hardness and flexibility at a high level, and that wrinkles and the like are less likely to occur when a member having a curved surface shape and a hard coat film are bonded to each other. The task is to do.

As a result of diligent studies on the above problems, the present inventor has found that the above problems can be easily solved by using a hard coat film having a hard coat layer on at least one side of the copolymerized polyester film, and completed the present invention. I came to let you.

That is, the gist of the present invention is to have a hard coat layer on at least one side of a copolymerized polyester film having a storage elastic modulus ^E'at 100 ° C. of 2.0 × 109 Pa or less and a haze of 8% or less. It exists in the hard coat film characterized by that.

By using the hard coat film according to the present invention, it is possible to achieve both surface hardness and flexibility at a high level, and an image display device such as a liquid crystal display or an organic EL display, or an input device such as a touch panel. , Suitable for various components of various terminals (game devices, personal computers, tablets, mobile phones, smartphones, smart glasses, etc.).

It is sectional drawing which shows typically the example of the hard coat film which is an Example of this invention.

Hereinafter, the present invention will be described in more detail.

<Copolymerized polyester film>
The copolymerized polyester film constituting the hard coat film of the present invention may have a single-layer structure or a laminated structure. For example, as long as the gist of the present invention is not exceeded other than the two-layer and three-layer structure, 4 It may be a layer or more layers, and is not particularly limited. Further, for example, in the case of a three-layer structure (surface layer / intermediate layer / surface layer), either one or two layers of the surface layer or the intermediate layer are used as a copolymerized polyester component, and the other layers are made of a copolymerized component. It is also possible to configure it with a polyester component that does not contain it.

Further, the copolymerized polyester film refers to a film obtained by cooling a molten polyester sheet extruded by an extrusion method and then stretching it, if necessary.

As the dicarboxylic acid component, terephthalic acid is preferable as the copolymerized polyester, and in addition, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid and diphenyl ether dicarboxylic acid. One or more of known dicarboxylic acids such as an acid and a cyclohexanedicarboxylic acid may be contained as a copolymerization component. Ethylene glycol is preferable as the diol component, and propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, and neopentyl are also preferable. One or more known diols such as glycol may be contained as a copolymerization component.
Among them, the copolymerized polyethylene terephthalate having one or more as a copolymerization component from the group consisting of phthalic acid and isophthalic acid as a dicarboxylic acid component and 1,4-cyclohexanedimethanol, 1,4-butanediol and diethylene glycol as a diol component is more suitable. preferable.

The content of the copolymerization component is preferably 1 mol% or more and 50 mol% or less, more preferably 3 mol% or more or 40 mol% or less, and further preferably 4 mol% or more or 30 mol% or less. When the content of the copolymerization component is 1 mol% or more, a concave shape, a convex shape, or an uneven shape can be formed on the surface of the pressure-sensitive adhesive sheet when laminated with the pressure-sensitive adhesive sheet. On the other hand, when it is 50 mol% or less, not only it has sufficient dimensional stability, but also it is possible to sufficiently suppress the occurrence of wrinkles during processing.

The melting point of the copolymerized polyester is preferably designed to be in the range of 260 ° C. or lower, more preferably 200 to 255 ° C. When the melting point is 260 ° C. or lower, sufficient strength can be obtained even in a heat treatment at a temperature lower than the melting point of the copolymerized polyester film in the heat treatment step after stretching.

It is desirable to contain particles in the copolymerized polyester film from the viewpoint of improving film workability. The particles include inorganic particles such as calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, lithium phosphate, magnesium phosphate, calcium phosphate, lithium fluoride, aluminum oxide, silicon oxide and kaolin; organic particles such as acrylic resin and guanamine resin. Particles; Precipitated particles obtained by granulating the catalyst residue can be mentioned, but are not limited thereto. The particle size of these particles and the content in the copolymerized polyester film can be appropriately determined according to the purpose. The particles to be contained may be a single component, or two or more components may be used at the same time. Further, various stabilizers, lubricants, antistatic agents and the like can be appropriately added.

The average particle size of the particles contained in the copolymerized polyester film is preferably 0.1 to 5.0 μm. When the average particle size of the particles is less than 0.1 μm, the slipperiness of the film may be insufficient and the workability may be lowered. On the other hand, if the average particle size of the particles exceeds 5.0 μm, the smoothness of the film surface may be impaired.

The content of the particles contained in the copolymerized polyester film is preferably 0.01 to 0.3% by weight. If the content of the particles is less than 0.01% by weight, the slipperiness of the film may be insufficient and the workability may be lowered. On the other hand, if the content of the particles exceeds 0.3% by weight, the smoothness of the film surface may be impaired.

The method of adding the particles to the copolymerized polyester film is not particularly limited, and a known method can be adopted. For example, it can be added at any stage in which polyester is produced, but is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification or at the stage after the completion of the transesterification reaction and before the start of the polycondensation reaction. The condensation reaction may proceed. Further, a method of blending a slurry of particles dispersed in ethylene glycol or water with a polyester raw material using a kneading extruder with a vent, or a method of blending dried particles with a polyester raw material using a kneading extruder. It is carried out by a method, a method of precipitating particles in a polyester manufacturing process system, or the like.

The ultimate viscosity of the copolymerized polyester is usually 0.40 to 1.10 dl / g, preferably 0.45 to 0.90 dl / g, and more preferably 0.50 to 0.80 dl / g. If the ultimate viscosity is less than 0.40 dl / g, the mechanical strength of the film tends to be weak, and if the ultimate viscosity exceeds 1.10 dl / g, the melt viscosity becomes high and the extruder is overloaded. In some cases.

Next, a production example of the copolymerized polyester film will be specifically described, but the present invention is not limited to the following production examples.

First, a method of using the above-mentioned copolymerized polyester raw material and cooling and solidifying the molten sheet extruded from the die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the smoothness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and / or the liquid coating adhesion method is preferably adopted.
The unstretched sheet obtained next is preferably stretched at least in the uniaxial direction, and more preferably biaxially stretched in the biaxial direction. For example, as biaxial stretching, in the case of sequential biaxial stretching, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine in the mechanical direction. The stretching temperature is usually 70 to 120 ° C., preferably 75 to 110 ° C., and the stretching ratio is usually 2.5 to 7.0 times, preferably 3.0 to 6.0 times. Then, it is stretched in the direction perpendicular to the stretching direction (mechanical direction) of the first stage (width direction). The stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7.0 times, preferably 3.5 to 6.0 times. Then, the heat treatment is subsequently performed at a temperature of 150 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially oriented film. In the biaxial stretching, a method of performing unidirectional stretching in two or more steps can also be adopted. In that case, it is preferable to finally set the stretching ratios in the two directions within the above ranges.

Further, regarding the production of the copolymerized polyester film, the simultaneous biaxial stretching method can also be adopted. The simultaneous biaxial stretching method is a method in which the unstretched sheet is simultaneously stretched and oriented in the mechanical direction and the width direction in a state where the temperature is controlled at 70 to 120 ° C., preferably 75 to 110 ° C., and the stretching ratio is as follows. The area magnification is preferably 4 to 50 times, more preferably 7 to 35 times, still more preferably 10 to 25 times. Then, the heat treatment is subsequently performed at a temperature of 150 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially stretched film. As for the simultaneous biaxial stretching device that adopts the above-mentioned stretching method, a conventionally known stretching method such as a screw method, a pantograph method, and a linear drive method can be adopted.

The storage elastic modulus E'at 100 ° C. of the copolymerized polyester film is 2.0 × 10 ⁹ Pa or less, preferably 1.0 × 10 ⁹ Pa or less. By satisfying the above range, a hard-coded film having good moldability such as followability to a curved surface shape can be obtained. In order for the storage elastic modulus E'at 100 ° C. to satisfy the above range, it can be satisfied by adjusting the type and content of the copolymerization component contained in the copolymerized polyester film.
On the other hand, the lower limit is not particularly limited, but 1.0 × 10 ⁷ Pa or more is preferable, and 1.0 × 10 ⁸ Pa or more is more preferable.

The haze of the copolymerized polyester film is 8% or less, preferably 5% or less, and more preferably 3% or less. If the haze exceeds 8%, when used as an image display device member such as a display, there is a possibility that problems such as impaired design, poor light transmission, and poor visibility may occur.

The heat shrinkage rate of the copolymerized polyester film after heating at 120 ° C. for 5 minutes is preferably 4.0% or less, more preferably 2.5% or less. By setting the heat shrinkage rate to 4.0% or less, when it is used as a hard coat film for curved surface processing, wrinkles and the like do not occur during curved surface processing, and sufficient workability can be obtained. In order for the heat shrinkage rate to satisfy the above range, it can be satisfied by adjusting the type and content of the copolymerization component contained in the copolymerized polyester film.

Above all, the shrinkage rate in the mechanical direction (MD) after heating at 120 ° C. for 5 minutes is preferably 4.0% or less, preferably 2.5% or less. On the other hand, the lower limit is not particularly limited, but is preferably 0.1% or more, and more preferably 0.5% or more.

Further, the shrinkage rate in the machine direction and the direction perpendicular to the machine direction (TD) after heating at 120 ° C. for 5 minutes is preferably 1.0% or less, preferably 0.8% or less. On the other hand, the lower limit is not particularly limited, but is preferably −1.0% or higher, more preferably −0.5% or higher.

<Hard coat layer>
The hard coat film of the present invention has a hard coat layer on at least one side of the copolymerized polyester film. As the hard coat layer constituting the hard coat film, the pencil strength of the hard coat layer is more preferably H or more, and further preferably 2H or more. When the pencil strength of the hard coat layer is H or more, it is possible to protect the surface of the hard coat film from scratches and stains.

Examples of the hard coat layer include a cured product layer formed by using various hard coat agents. For example, the hard coat layer is formed by using a hard coat agent containing an active energy ray-curable composition and a thermosetting composition. Layers are mentioned.

The material used for the hard coat agent is not particularly limited as long as it satisfies the pencil hardness. For example, it may contain a polymerizable monomer, a polymerizable oligomer, or the like that forms a cured product by irradiation with active energy rays.
Examples of the polymerizable monomer or the polymerizable oligomer include a (meth) acrylate monomer having a radically polymerizable unsaturated group in the molecule and a (meth) acrylate oligomer having a radically polymerizable unsaturated group in the molecule. Be done.
Examples of the (meth) acrylate monomer having a radically polymerizable unsaturated group in the molecule or the (meth) acrylate oligomer having a radically polymerizable unsaturated group in the molecule include urethane (meth) acrylate and polyester (meth). ) Monomers or oligomers such as acrylates, epoxy (meth) acrylates, melamine (meth) acrylates, polyfluoroalkyl (meth) acrylates, silicone (meth) acrylates and the like. These polymerizable monomers or polymerizable oligomers may be used alone or in combination of two or more. Of these, urethane (meth) acrylate is preferable because it has both high surface hardness and flexibility.

The urethane (meth) acrylate is, for example, a urethane (meth) acrylate obtained by reacting a polyisocyanate compound with a (meth) acrylate compound having one hydroxyl group in the molecular structure, or a polyisocyanate compound having a hydroxyl group in the molecular structure. An example is urethane (meth) acrylate obtained by reacting one (meth) acrylate compound with a polyol compound.

As the material used for the hard coat agent, a cured product of polyfunctional (meth) acrylate may be contained.
Examples of the polyfunctional (meth) acrylate include trimethyl propanetri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, and pentaerythritol tri (meth). ) Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethyl propantri (meth) acrylate, Ditrimethylol propanetetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol octa (meth) acrylate, tetrapentaerythritol deca (meth) acrylate, isocyanuric acid tri (meth) acrylate, isocyanuric acid di (meth) Acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin tetra (meth) acrylate, adamantyldi (meth) acrylate, isoboronyldi (meth) acrylate, dicyclopentane (meth) ) Acrylate, tricyclodecandi (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate, and those modified with PO, EO, caprolactone and the like can be mentioned.
Among these, those having 3 to 6 functionalities are more preferable because they can preferably satisfy the surface hardness, and for example, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), pentaerythritol tetraacrylate (PETTA), and the like. Dipentaerythritol pentaacrylate (DPPA), trimethylolpropane tri (meth) acrylate, tripentaerythritol octa (meth) acrylate, tetrapentaerythritol deca (meth) acrylate and the like are preferable.

In the present invention, in order to obtain a hardcoat film having both high surface hardness and flexibility, it is preferable that the hardcoat layer contains a cured product of the urethane (meth) acrylate and the polyfunctional (meth) acrylate. ..
The blending ratio of the urethane (meth) acrylate (A) and the tripentaerythritol octa (meth) acrylate (B) is preferably (A) / (B) = 90/10 to 10/90 in terms of weight ratio, and (A). / (B) = 80/20 to 40/60 is more preferable.

Additives such as a cross-linking agent, a polymerization initiator, a lubricant, a plasticizer, organic particles, inorganic particles, an antifouling agent, an antioxidant, and a catalyst may be added to the hard coat agent as long as the physical properties are not impaired.

Further, if necessary, the hard coat agent may contain a solvent. Examples of the solvent include alcohols (methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol, diacetone alcohol); ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, Cyclopentanone, cyclohexanone, heptanone, diisobutylketone, diethylketone, diacetone alcohol); esters (methyl acetate, ethyl acetate, butyl acetate, n-propyl acetate, isopropyl acetate, methyl acrylate, PGMEA); aliphatic hydrocarbons (hexane) , Cyclohexane); Halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride); Aromatic hydrocarbons (benzene, toluene, xylene); Amidos (dimethylformamide, dimethylacetamide, n-methylpyrrolidone); Ethers (diethyl ether, Dioxane, tetrahydrofuran); ether alcohol (1-methoxy-2-propanol); carbonates (dimethyl carbonate, diethyl carbonate, ethylmethyl carbonate) and the like. These solvents may be used alone or in combination of two or more.

The thickness of the hard coat layer of the present invention is preferably 1 μm to 50 μm, more preferably 2 μm to 40 μm, still more preferably 3 μm to 25 μm. When the thickness of the hard coat layer satisfies the above range, it is possible to prevent the hard coat film from being scratched, and even when the hard coat film is directly attached to another member as a component for the image display device, the configuration for the image display device. It is possible to effectively prevent the member from being damaged. Further, when the hard coat layer is formed, it is possible to prevent the hard coat film and the protective adhesive film from being warped due to the curing shrinkage of the hard coat agent.

As a method of providing the hard coat layer on the copolymerized polyester film, a conventionally known coating method such as a reverse gravure coat, a direct gravure coat, a roll coat, a die coat, a bar coat, and a curtain coat can be used. Regarding the coating method, there is a description example in "Coating method" (Maki Shoten, Yuji Harasaki, published in 1979).

Further, in order to provide the hard coat layer, the copolymerized polyester film may be subjected to surface treatment such as corona treatment, plasma treatment, and ultraviolet irradiation treatment in advance.

The method for drying the hard coat layer is not particularly limited, but it is generally preferable to dry the hard coat layer at 30 to 160 ° C.
Further, as a method for curing the hard coat layer, a known method may be appropriately selected depending on the composition of the hard coat agent and the like. For example, if the hard coat agent is an active energy ray-curable type, it may be cured by irradiating it with active energy rays (visible light, ultraviolet rays, X-rays, γ-rays). At this time, the irradiation amount of the active energy ray may be appropriately adjusted according to the characteristics of the hard coat agent, but it is generally preferable to irradiate at 10 to 10000 mJ / m ² .

<Hardcourt film>
Since the hard coat film of the present invention has high surface hardness and flexibility, curved surface processing is possible.
The curvature of the hardcourt film of the present invention measured by the cylindrical mandrel bending tester is preferably 5 mm or less, more preferably 3 mm or less. When the curvature of the hard coat film is 5 mm or less, the occurrence of defects such as cracking of the hard coat layer and peeling from the copolymerized polyester film is suppressed, and the hard coat film has sufficient flexibility for curved surface processing.

The thickness of the hard coat film of the present invention is preferably 9 μm to 250 μm, more preferably 2 μm to 125 μm, and even more preferably 25 μm to 75 μm.
If the thickness is less than 9 μm, the film tension may be insufficient, which may cause problems such as easy wrinkling at the time of slitting. On the other hand, if it exceeds 250 μm, when it is used as a hard coat film for curved surface processing, the followability to a member having a curved surface shape may be insufficient.

The hard-coated film of the present invention can be used, for example, as a surface protective film in various products, a surface protective film in members or parts of various products, or as a constituent material of various products or members or parts thereof. You can also do it. Examples of the above products include display devices such as liquid crystal displays and organic EL displays; input devices such as touch panels: solar cells; various home appliances; various electric / electronic products; portable electronic terminals (for example, game devices, personal computers, tablets, etc.). Various electric and electronic products (smartphones, mobile phones, etc.); various optical devices, etc. can be mentioned. Further, as an embodiment in which the hard coat film of the present invention is used as a constituent material of various products and their members or parts, for example, an embodiment in which a hard coat film and a transparent conductive film are laminated in a touch panel and the like can be mentioned. Be done.

The hard-coated film of the present invention may be provided with an adhesive layer on the surface of the copolymerized polyester film in order to be bonded to the constituent materials of various products, members or parts. The adhesive layer is not particularly limited, but is limited to acrylic adhesive, natural rubber adhesive, synthetic rubber adhesive, ethylene-vinyl acetate copolymer adhesive, ethylene- (meth) acrylic acid ester copolymer adhesive. Specific examples thereof include a pressure-sensitive adhesive layer formed from one or more of known pressure-sensitive adhesives such as an agent, a styrene-isoprene block copolymerization system pressure-sensitive adhesive, and a styrene-butadiene block copolymerization system pressure-sensitive adhesive. Further, the adhesive layer may contain various additives (antistatic agent, slip agent, etc.), if necessary.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. Various physical properties and characteristics are measured or defined as follows.

(1) Extreme viscosity of polyester (dl / g)
1 g of polyester from which other components incompatible with polyester had been removed was precisely weighed, 100 ml of a mixed solvent of phenol / tetrachloroethane = 50/50 (weight ratio) was added and dissolved, and the measurement was carried out at 30 ° C.

(2) Average particle size (i) In the case of added particles The average particle size is determined by the sedimentation method based on the resistance value of the stokes using a centrifugal sedimentation type particle size distribution measuring device (SA-CP3 type, manufactured by Shimadzu Corporation). It was measured.
(Ii) In the case of precipitated particles A polyester film containing particles was sandwiched between slides, melted, and then cooled, and the sample was observed under a microscope. From the microscope image, the average particle size was measured using an image processing device (Quantimet500 +, manufactured by Leica).
The concentration of the precipitated particles can be obtained by adding 1.0 liter of o-chlorophenol to 100 g of polyester, heating at 120 ° C. for 3 hours, and then centrifuging for 40 minutes using an ultracentrifuge (55P-72) manufactured by Hitachi Koki. The particles were vacuum dried at 100 ° C. and measured.
If a melting peak corresponding to the polymer is observed when the particles are measured with a scanning differential calorimeter, o-chlorophenol is added to the particles, the particles are heated, cooled, and then centrifuged again. Was done. When no melting peak was observed, the particles were designated as precipitated particles.

(3) Thickness A small piece of film was fixedly molded with an epoxy resin, cut with a microtome, and the cross section of the film was observed by a transmission electron micrograph. Of the cross section, the interface is observed by light and dark almost parallel to the film surface. The distance between the interface and the film surface was measured from 10 photographs, and the average value was taken as the thickness.

(4) Haze The haze was measured with an integrating sphere type turbidity meter (NDH-20D, manufactured by Nippon Denshoku Kogyo Co., Ltd.) according to JIS K7105.

(5) Storage elastic modulus With respect to the obtained film, a sample of 30 mm in the longitudinal direction × 5 mm in the width direction was taken so that the longitudinal direction was the mechanical direction. Next, using a dynamic viscoelastic device (“DVA-220” manufactured by IT Measurement Control Co., Ltd.), the sample was sandwiched and fixed in a chuck set at an interval of 20 mm, and then the temperature rise rate was 10 ° C./min at room temperature. The storage elastic modulus was measured at a frequency of 10 Hz up to 200 ° C. From the obtained data, the storage elastic modulus at 100 ° C. was read.

(6) Heat treatment shrinkage A strip-shaped (15 mm width x 150 mm length) sample is cut out from the center position in the width direction of the obtained film so that the sample longitudinal direction is the measurement direction, and the oven (manufactured by TABAI: Heat treatment was performed in a hot air circulation furnace) in an atmosphere of 120 ° C. for 5 minutes, the length of the sample before and after the heat treatment was measured, and the heat shrinkage rate (%) of the film was calculated by the following formula. In the following formula, a is the sample length (mm) before the heat treatment, and b is the sample length (mm) after the heat treatment.
Heat shrinkage rate (%) = [(ab) / b] × 100

(7) Applicability of Hard Coat Layer The obtained copolymerized polyester film was applied offline by a reverse gravure coating method so that the thickness of the hard coat layer after drying was 5 μm. After coating, it was dried at 140 ° C. for 30 seconds to obtain a hardcourt film.
At this time, the coating suitability of the hard coat layer was evaluated from the evaluation criteria shown below, such as the transport status of the film.
(Evaluation criteria)
◯: A hard-coated film having a good appearance can be obtained without fluttering during film transportation or wrinkling during drying.
Δ: Due to the fluttering during film transportation, the hard coat film comes into contact with the coating device and causes slight scratches. Alternatively, slight wrinkles occur when drying.
X: The hard coat film comes into contact with the coating device due to fluttering during film transportation, and the entire surface is scratched. Or strong wrinkles occur when drying.

(8) Pencil hardness of the hard coat layer The pencil hardness of the hard coat layer was measured according to JIS K5600-5-4.

(9) Scratch resistance of the hard coat layer After 10 reciprocating steel wool # 0000 with a load of 500 g applied to the surface of the hard coat layer, the degree of scratches on the surface was visually observed and evaluated according to the following evaluation criteria.
(Evaluation criteria)
◯: No scratches occur. (No problem in practical use)
Δ: Slight scratches occur. (May be a problem in practice)
X: Scratches are clearly generated. (There is a problem in practical use)

(10) Evaluation of Flexibility of Hardcourt Film Flexibility was evaluated using a cylindrical mandrel bending tester according to JIS K5600-5-1. When the sample film for evaluation was wound around the test rod, an integer value (mm) of the maximum diameter at which problems such as cracks in the hard coat layer and delamination between the hard coat layer and the copolymerized polyester film occurred was measured. Evaluation was performed according to the following evaluation criteria, and a score of △ or higher was regarded as acceptable.
(Evaluation criteria)
◯: 3 mm or less Δ: 4 to 5 mm
×: 6 mm or more

The polyester raw materials used in the following examples and comparative examples were produced by the following methods.

<Manufacturing of polyester A>
100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, and 0.07 parts by weight of calcium acetate monohydrate were taken in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. About 4 hours after the reaction started. The temperature was raised to 230 ° C. in half, and the transesterification reaction was substantially completed. Next, 0.04 part by weight of phosphoric acid and 0.035 part by weight of antimony trioxide were added, and the mixture was polymerized according to a conventional method. That is, the reaction temperature was gradually increased to 280 ° C., while the pressure was gradually reduced to 0.05 mmHg. After 4 hours, the reaction was terminated and chips were obtained according to a conventional method to obtain polyester A. The ultimate viscosity of the obtained polyester A was 0.65 dl / g.

<Manufacturing of polyester B>
In the above method for producing polyester A, polyester B was produced by the same method as polyester A except that the dicarboxylic acid unit was 78 mol% of terephthalic acid and 22 mol% of isophthalic acid. The ultimate viscosity of the obtained polyester B was 0.70 dl / g.

<Manufacturing of polyester C>
When producing the polyester A, 3000 ppm of amorphous silica having an average particle size of 3 μm was added to prepare the polyester C.

<Manufacturing of polyester D>
When producing the polyester A, 6000 ppm of amorphous silica having an average particle size of 4 μm was added to prepare the polyester D.

[Example 1]
A raw material in which the polyesters A and C are mixed at a ratio of 90% by weight and 10% by weight, respectively, is used as a raw material for the surface layer, and a raw material in which polyesters B and A are mixed at a ratio of 35% by weight and 65% by weight is used for the intermediate layer. As a raw material, melt-extruded by different melt extruders (surface layer / intermediate layer / surface layer) to obtain an amorphous sheet of 2 types and 3 layers. Then, the sheet was co-extruded onto a cooled casting drum and cooled and solidified to obtain an unoriented sheet. Then, after stretching 3.4 times in the mechanical direction (longitudinal direction) at 82 ° C., further through a preheating step in the tenter, stretching 3.9 times in the width direction (horizontal direction) at 110 ° C., and 210 ° C. for 3 seconds. After that, a 2.4% relaxation treatment was performed in the width direction to obtain a polyester film having a thickness of 50 μm.
Next, a hard coat layer having the composition of the following hard coat layer was applied offline by a reverse gravure coat method so that the thickness after drying was 5 μm. After heat treatment at 80 ° C. for 5 minutes, the film was irradiated with ultraviolet rays at an integrated light intensity of 200 mJ / m ² to obtain a hardcourt film. The characteristics of this film are shown in Table 1.
(Composition of hard coat layer)
Urethane (meth) acrylate (A-1) 50 parts by weight Polyfunctional acrylate containing tripentaerythritol octaacrylate (B-1) 50 parts by weight Photopolymerization initiator (“Irgacure 184” manufactured by BASF Japan Ltd.) 3 parts by weight Acetic acid 80 parts by weight of butyl

(Manufacturing of urethane (meth) acrylate (A-1))
Nitrogen gas was blown into a 2 liter clean separable flask equipped with a stirrer, a gas introduction tube, a condenser, a dropping funnel and a thermometer, the air in the flask was replaced with nitrogen gas, and then the flask was filled with 336 g of hexamethylene diisocyanate. 352 g of butyl acetate, 0.1 g of dibutyltin diacetate and 0.5 g of methquinone were added, and the temperature was raised to 70 ° C. with stirring. Next, a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (“M-305” manufactured by Toagosei Co., Ltd., hydroxyl value: 110.0, pentaerythritol triacrylate / pentaerythritol tetraacrylate = 60/40 (mass). %)) 1,071 g was added over 1 hour. Further, the mixture was kept at 80 ° C. for 3 hours to obtain 1,616 g of a butyl acetate solution of urethane (meth) acrylate (A-1).
The property values of the urethane (meth) acrylate (A-1) were as follows. Non-volatile content: 80%, Gardner viscosity (25 ° C.): U, Gardner color: 1 or less, weight average molecular weight (Mw) of solid content: 1,250, (meth) acryloyl equivalent: 153 g / eq

[Example 2] to [Example 3]
A hard-coated film was obtained in the same manner as in Example 1 except that the conditions shown in Table 1 below were changed. The characteristics of the film are shown in Table 1.

[Example 4]
The raw materials obtained by mixing the polyesters B, A, and D at a ratio of 85% by weight, 10% by weight, and 5% by weight, respectively, were melt-extruded by a melt extruder to obtain a single-layer amorphous sheet.
Then, the sheet was co-extruded onto a cooled casting drum and cooled and solidified to obtain an unoriented sheet. Then, after stretching 3.4 times in the mechanical direction (longitudinal direction) at 80 ° C., and further undergoing a preheating step in the tenter, it is stretched 3.9 times in the width direction (horizontal direction) at 80 ° C. for 3 seconds at 185 ° C. After that, a 6.4% relaxation treatment was carried out in the width direction to obtain a polyester film having a thickness of 50 μm.
Next, a hard coat film was obtained by providing a hard coat layer in the same manner as in Example 1. The characteristics of the film are shown in Table 1.

[Example 5]
A hard-coated film was obtained in the same manner as in Example 4 except that the conditions shown in Table 1 below were changed. The evaluation results are shown in Table 1 below.

[Comparative Example 1] to [Comparative Example 2]
A hardcourt film was obtained in the same manner as in Example 1 except that the conditions shown in Table 2 below were changed. The evaluation results are shown in Table 2 below. Since the storage elastic modulus E'at 100 ° C. of the copolymerized polyester film was too high, the hard-coated film had insufficient flexibility.

[Comparative Example 3]
A polyester film was obtained in the same manner as in Example 4 except that the hard coat layer was not provided. The evaluation results are shown in Table 2 below. Since the hard coat layer was not provided, the surface hardness was insufficient.

The hard-coated film in the present invention has flexibility while maintaining high surface hardness, and can be manufactured and processed by a roll-to-roll method. For example, it is suitable for display devices such as liquid crystal displays and organic EL displays, input devices such as touch panels, and various terminals (for example, game devices, personal computers, tablets, mobile phones, smartphones, smart glasses, etc.).

Claims (9)

It has a copolymerized polyethylene terephthalate having a storage elastic modulus E'at 100 ° C. at a frequency of ¹⁰ Hz of 2.0 × 109 Pa or less, a haze of 8% or less, and a diol component of ethylene glycol. A copolymerized polyester film having a laminated structure of three seeds has a hard coat layer on at least one side thereof.
The intermediate layer of the copolymerized polyester film has a copolymerized polyethylene terephthalate having ethylene glycol as a diol component and containing terephthalic acid and isophthalic acid as a dicarboxylic acid component.
A hard-coated film for displays having a maximum diameter of 3 mm or less when the flexibility is evaluated using a cylindrical mandrel bending tester according to JIS K5600-5-1. It has a copolymerized polyethylene terephthalate having a storage elastic modulus E'at 100 ° C. at a frequency of ¹⁰ Hz of 2.0 × 109 Pa or less, a haze of 8% or less, and a diol component of ethylene glycol. A copolymerized polyester film having a laminated structure of three seeds has a hard coat layer on at least one side thereof.
At least one layer of the copolymerized polyester film has a copolymerized polyethylene terephthalate in which the diol component is ethylene glycol and one or more of terephthalic acid and isophthalic acid as a dicarboxylic acid component is contained as a copolymerization component.
The intermediate layer has a copolymerized polyethylene terephthalate containing ethylene glycol as a diol component and terephthalic acid and isophthalic acid as a dicarboxylic acid component.
A hard-coated film for displays having a maximum diameter of 3 mm or less when the flexibility is evaluated using a cylindrical mandrel bending tester according to JIS K5600-5-1. Each of the layers constituting the laminated structure contains a polyester having a dicarboxylic acid component of terephthalic acid and a diol component of ethylene glycol, and the intermediate layer contains 35 to 45% by weight of the copolymerized polyethylene terephthalate. The hard coat film for a display according to claim 1 or 2 , which is contained in a proportion. The hard coat film for a display according to any one of claims 1 to 3, wherein the hard coat layer contains a cured product of urethane (meth) acrylate or polyfunctional (meth) acrylate. The hard coat film for a display according to any one of claims 1 to 4, wherein the pencil hardness of the hard coat layer is H or more. The copolymerized polyester film is characterized in that the storage elastic modulus E'at 100 ° C. at a frequency of 10 Hz is 1.2 × 10 ⁹ Pa or more and 2.0 × 10 ⁹ Pa or less. 5. The hard coat film for a display according to any one of 5. A hard coat film for curved surface processing using the hard coat film for display according to any one of claims 1 to 6. A laminated body having a structure in which the hard coat film for a display according to any one of claims 1 to 6 and a member having a curved surface shape are bonded to each other. A method for using a display hard coat film, which comprises attaching the display hard coat film according to any one of claims 1 to 6 to a member having a curved surface shape.

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