JP2009009099A - Luminance improving sheet and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical sheet having excellent abrasion resistance. <P>SOLUTION: The optical sheet has a flexible support body, a molding layer containing active energy ray curable resin and 0.02-30.0 mg/m<SP>2</SP>lubricant on the front face of the flexible support body, and a lubricant layer containing 0.02-10.0 mg/m<SP>2</SP>lubricant on the rear face of the flexible support body. The optical sheet has a low friction coefficient and excellent abrasion resistance on both faces. As the lubricant, at least one kind selected from a group consisting of fatty acid ester and fatty acid is preferable. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a brightness enhancement sheet provided with a molding layer containing an active energy ray-curable resin on one surface of a flexible support and a method for producing the same.

  Up to now, optical sheets having a concavo-convex pattern on the surface have been mainly used as decorative members such as building materials. However, in recent years, optical films such as antireflection films, diffusion sheets, brightness enhancement sheets, light guide plates, diffraction gratings, patterned It is widely used for members such as media, information recording media, optical elements, holograms, and microchannels. In particular, the use of an optical sheet having a concavo-convex pattern in an optical film application represented by an antireflection film or the like, or an information recording medium application having a tracking layer such as a CD (compact disc) or a DVD (digital versatile disc). It has increased. In these applications, miniaturization of the concavo-convex pattern has become important in order to improve the performance of optical characteristics. For example, it has been proposed to improve the antireflection function by reducing the pitch of the concavo-convex pattern to a submicron order of visible light wavelength or less (for example, Non-Patent Document 1).

Among the optical sheets described above, as a method for producing a brightness enhancement sheet, in addition to an injection molding method or an extrusion molding method for directly molding a base material, a molding layer having an active energy ray curable resin such as an ultraviolet curable resin is flexible. There is a method of forming on a conductive support. For example, a resin layer containing an active energy ray-curable resin or the like is applied onto a flexible support to form a resin layer, and an emboss pattern on a molding roll is transferred to the uncured resin layer to form a resin layer. The resin layer is cured by irradiating the molded resin layer with active energy rays such as ultraviolet rays to form a molding layer having a concavo-convex pattern, and the original fabric roll having the formed molding layer is formed to a predetermined length. A method for producing a brightness enhancement sheet by cutting the sheet is known (for example, Patent Documents 1 and 2). According to the method of forming a molding layer using this active energy ray-curable resin, a fine concavo-convex pattern can be formed with high accuracy and thermal damage to the flexible support can be avoided. Moreover, since a shaping | molding layer is formed continuously, a brightness improvement sheet | seat can be manufactured cheaply.

  By the way, this type of optical sheet has a concavo-convex pattern due to rubbing between optical sheets when stacked and conveyed after manufacture, contact with a liquid crystal member or the like when incorporated in an optical device such as a liquid crystal device, and sliding. The formed layer on which is formed and its opposite surface are easily damaged. In particular, since the flexible support is exposed on the opposite surface of the molding layer, a soft flexible support such as a polyester film is easily damaged, which may lead to a decrease in optical properties.

Therefore, in a light diffusion sheet or the like, a polymer having a quaternary ammonium base, a (meth) acryloyl group and a polyorganosiloxane unit, and a polyfunctional (meth) having three or more (meth) acryloyl groups in the molecule. It has been proposed to improve the film hardness of both layers by using an ionizing radiation curable composition having an acrylate for the light diffusion layer and the backcoat layer (for example, Patent Document 3).
Japanese Patent No. 3016638 Japanese Patent No. 3490099 JP 2002-98809 A PBClapham and MCHutley, Nature (London) 244, p.281-282 (1973)

However, for example, when an optical member made of a hard acrylic resin such as a diffusion plate and a brightness enhancement sheet are arranged to overlap each other, scraping powder of the acrylic resin may be interposed between the brightness enhancement sheet and the diffusion plate. . In such a case, since the acrylic resin is harder than the ionizing radiation curable resin contained in the molding layer and the backcoat layer in Patent Document 3, the luminance enhancement sheet is brought into contact with and slid with the acrylic resin powder to improve the luminance. Both sides of the sheet are easily damaged. In addition, the production cost is increased by forming the back coat layer. In Patent Documents 1 and 2, a silicone surfactant that is considered to have lubrication performance is added to the resin solution together with the active energy ray curable resin, but the silicone surfactant is uniformly dispersed depending on the type of resin. The resin solution may become cloudy. In addition, since the silicone surfactant is not uniformly dispersed in the resin, a large amount of the silicone surfactant is present on the surface of the molding layer, and there is a problem that the coefficient of friction is increased and scratches are easily generated.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a brightness improving sheet excellent in scratch resistance at a low cost.

The present inventors have focused on the slipperiness of both sides of the brightness enhancement sheet and found that the scratch resistance can be improved at a low cost by optimizing the slipperiness of both sides.

That is, the present invention is formed by irradiating an active energy ray to a flexible support and an uneven pattern formed by molding a resin layer on the surface of the flexible support. containing a forming layer containing a lubricant rESIN and 0.1~28.8 mg / ^{m 2,} the lubricant .06 to 9.5 mg / ^{m 2} on a back surface of the flexible support A brightness enhancement sheet having a lubricant layer.
According to the brightness enhancement sheet, since the molding layer containing the lubricant and the lubricant layer are provided on both sides of the flexible support, the friction coefficient on both sides of the brightness enhancement sheet can be reduced. Then, each of the molded layer and a lubricant layer for lubricating agent 0.06~9.5 mg / ^{m 2} containing a 0.1~28.8 mg / ^{m 2,} the sticking of the brightness improving sheet duplex Scratch resistance can be improved without occurring. That is, if the brightness enhancement sheet molding layer and a lubricant layer are formed, each containing the predetermined amount of lubricant is slid stacked brightness improving sheet in a state where the dust is interposed between the brightness enhancing sheet However, since the brightness enhancement sheets are in contact with each other with little sticking, and dust easily slips between the molding layer and the lubricant layer, the occurrence of scratches on both sides can be suppressed. For this reason, even if a brightness improvement sheet contacts and slides with the hard foreign material which consists of an acrylic resin etc., generation | occurrence | production of a damage | wound can be reduced.
The molding layer and the lubricant layer contain at least one selected from the group consisting of fatty acid esters and fatty acids. Since fatty acid esters and fatty acids are excellent in dispersibility in the active energy ray-curable resin, it is possible to prevent white turbidity of the resin solution. Further, since these lubricants have a large effect of reducing the friction coefficient, the scratch resistance can be improved. In particular, when a fatty acid ester and a fatty acid are used in combination, a brightness improving sheet excellent in scratch resistance can be obtained even in a cycle test from a low temperature to a high temperature.
Further, in the brightness enhancement sheet, the forming layer, it contains more lubricant than the lubricant layer. Since the molding layer which is an optical functional layer has fine irregularities and is easily damaged by this, the lubricant content of the molding layer is preferably larger than that of the lubricant layer. On the other hand, since the lubricant layer has a smooth surface compared to the molded layer, if the lubricant content of the lubricant layer is too much than that of the molded layer, the surface of the lubricant layer is increased when a plurality of brightness enhancement sheets are stacked. The back side becomes easy to stick.

Further, when the content of the lubricant in the molding layer is Cs and the content of the lubricant in the lubricant layer is Cb, the difference between Cs and Cb (Cs−Cb) preferably satisfies the following relationship.
0 mg / m ² <(Cs−Cb) ≦ 7.0 mg / m ²
If the difference in the content of the lubricant between the molded layer and the lubricant layer is within the above range, the blocking property between the brightness enhancement sheets can be further improved.

The fatty acid ester preferably has a melting point of 80 ° C. or lower. Since the fatty acid ester has a low melting point, the friction coefficient on both sides of the brightness enhancement sheet can be further reduced. Moreover, since the low melting point fatty acid ester has high mobility, the fatty acid ester dispersed in the active energy ray-curable resin is likely to ooze out on the surface of the molding layer. For this reason, the fatty acid ester in a shaping | molding layer can be transcribe | transferred to the back surface of a flexible support body by forming the original fabric roll which has a shaping | molding layer containing fatty acid ester. Thereby, it is not necessary to separately provide a process for forming the lubricant layer, and the brightness enhancement sheet can be manufactured at a low cost.

  The fatty acid ester preferably has a melting point of 25 ° C. or lower. If the low melting point fatty acid ester is used, the friction coefficient can be further reduced. Moreover, since the said fatty acid ester tends to exude further to the surface of a shaping | molding layer by aging, the fatty acid ester in a shaping | molding layer can be efficiently transcribe | transferred to the back surface of a flexible support body.

The fatty acid preferably has a melting point of 25 to 80 ° C. The fatty acid is excellent in reducing the friction coefficient in a low temperature environment. In addition, when a fatty acid ester and the above-mentioned fatty acid are used in combination as a lubricant, a brightness-enhancing sheet that is further excellent in scratch resistance in a cycle test from a low temperature to a high temperature can be obtained.

The fatty acid preferably has a melting point that is 25 ° C. higher than the melting point of the fatty acid ester. The brightness enhancement sheet is excellent in scratch resistance even in a wide temperature environment from low temperature to high temperature.

  The active energy ray-curable resin preferably contains a diacrylate or dimethacrylate having a bisphenol A skeleton as a main component. Since the active energy ray-curable resin is excellent in moldability, it is possible to form a molding layer having a fine uneven pattern. The resin is excellent in the dispersibility of the lubricant, particularly fatty acid ester and fatty acid. Further, when the molding layer contains the active energy ray-curable resin and a lubricant such as fatty acid ester or fatty acid, the lubricant tends to ooze out on the surface of the molding layer, so that the back surface of the flexible support is lubricated. The agent can be sufficiently transferred, and the friction coefficient can be further reduced.

And in manufacture of the said brightness improvement sheet | seat , 0.01-5 mass% lubricant with respect to the active energy ray-curable resin and resin component whole quantity provided in the surface of the flexible support body conveyed continuously, Forming a concavo-convex pattern on the resin layer by bringing a molding roll into contact with the resin layer containing the resin layer, irradiating the molded resin layer with an active energy ray to form a molded layer by curing the resin layer, A production method is preferred in which the flexible support on which the molding layer is formed is wound into a roll to form an original roll, and the original roll is aged at a temperature of 30 to 100 ° C.
According to the above production method, a resin layer containing an active energy ray-curable resin and a certain amount of lubricant is molded with a molding roll, and after the resin layer is cured, 30 rolls of the raw fabric roll are wound. By aging at ˜100 ° C., the lubricant in the molding layer can be efficiently transferred to the back surface of the flexible support. Moreover, according to the said manufacturing method, the curvature and wave | undulation of a brightness improvement sheet | seat can be suppressed.

  The resin layer preferably contains at least a fatty acid ester having a melting point of 25 ° C. or less as the lubricant. Since the low melting point fatty acid ester has high mobility in the molding layer and easily oozes onto the surface of the molding layer, the lubricant can be efficiently transferred to the back surface of the flexible support even by using a small amount. .

According to the said brightness improvement sheet | seat and manufacturing method, the brightness improvement sheet | seat excellent in abrasion resistance can be provided cheaply.

FIG. 1 is a schematic cross-sectional view showing an example of the basic configuration of the brightness enhancement sheet according to the present embodiment. As shown in FIG. 1, a molding layer 3 that is an optical functional layer is formed on the surface of the flexible support 2, and a lubricant layer 4 is formed on the back surface of the flexible support 2. Yes.

  As the flexible support 2, a conventionally known flexible support used in optical films, information recording media and the like can be used. In general, there are flexible films made of various synthetic resins. Specific examples include polyethylene terephthalate (PET) film, polyethylene naphthalate film, polyamide film, polyaramid film, polyimide film, polycarbonate film, polyphenylene sulfide film, polysulfone film, and polypropylene film. Among these, a polyethylene terephthalate film is preferable from the viewpoint of optical properties, mechanical strength, dimensional stability, heat resistance, price, and the like, and a biaxially stretched polyethylene terephthalate film is particularly preferable. The thickness of the flexible support to be used is not particularly limited, but a flexible support having a thickness of usually 300 μm or less is used according to the application. In particular, in the case of an optical film application such as an antireflection film, the thickness of the flexible support is preferably 200 μm or less. Since such a thin film is easily scratched, the effect of lowering the friction coefficient by providing a molding layer and a lubricant layer containing a lubricant is more remarkable. Moreover, in order to improve the adhesiveness of the shaping | molding layer with respect to a film, surface treatments, such as a corona and a plasma treatment, may be performed, and the easily bonding layer which has a polyurethane, polyester, etc. on the surface may be provided.

  The average surface roughness (Ra) of the flexible support is preferably 1 μm or less, more preferably 0.5 μm or less, and most preferably 0.1 μm or less. Further, the ten-point average surface roughness (Rz) of the flexible support is preferably 5 μm or less, more preferably 3 μm or less, and most preferably 0.5 μm or less. Such a flexible support having surface properties with excellent smoothness suppresses irregular reflection of light and is excellent in optical properties, while the contact area increases, so the friction coefficient becomes high and scratches are likely to occur. . Therefore, the effect of lowering the coefficient of friction is more significantly exhibited by providing the molding layer and the lubricant layer containing the lubricant.

Molding layer 3 together with the active energy ray-curable resin, a lubricant and 0.1 to 28.8 mg / ^{m 2,} more preferably 1.5~13.0mg / ^{m 2} containing. By forming the molding layer containing the lubricant, the friction coefficient of the molding layer can be reduced and the slipperiness can be improved. Further, if a molding layer containing a lubricant in the above range and a lubricant layer containing a certain amount of lubricant are formed, the friction coefficient can be lowered without causing sticking on both sides of the brightness enhancement sheet. . In addition, even if the brightness enhancement sheets are stacked and slid with dust interposed between the brightness enhancement sheets, the dust is easily slid between the molding layer and the lubricant layer, thereby suppressing the occurrence of scratches on both sides. Can do. When the content of the lubricant in the molding layer is less than 0.1 mg / m ² , the lubrication performance is insufficient, the slipperiness cannot be sufficiently improved, and the scratch resistance is deteriorated. When the content of the lubricant in the molding layer is more than 28.8 mg / m ² , since the lubricant is present in a large amount in the molding layer, the molding layer becomes soft and the friction coefficient becomes high. For this reason, it becomes easy to produce sticking and it becomes easy to enter a crack. Further, in the case of a lubricant that is solid at room temperature, there is a tendency that bleed out occurs due to a large amount of the lubricant exuded on the surface, resulting in poor appearance. Note that the content of the lubricant in the molding layer can be obtained by washing the molding layer with hexane.

Examples of lubricants include fatty acid esters; fatty acids; aliphatic amides; aliphatic alcohols; aliphatic amines; monosulfides; hydrocarbon compounds such as liquid paraffin, squalane and synthetic squalane; silicone compounds; fatty acids and fluorinated alcohols Examples of the ester include fluorine compounds such as fluoropolyether. These may be used alone or in combination. Among these, the molding layer preferably contains at least one selected from the group consisting of fatty acid esters and fatty acids, more preferably contains at least fatty acid esters, and contains both fatty acid esters and fatty acids. Is more preferable. Fatty acid esters and fatty acids have a large friction coefficient reducing effect. Moreover, since these lubricants are excellent in dispersibility in the active energy ray-curable resin as compared with other lubricants such as silicone compounds, the cloudiness of the resin solution can be prevented. Fatty acid esters increase in viscosity and the friction coefficient may increase in a low temperature environment, but fatty acids have a small increase in friction coefficient even in a low temperature environment. For this reason, if a fatty acid ester and a fatty acid are used in combination, a brightness enhancement sheet having excellent scratch resistance can be obtained even in a cycle test from a low temperature to a high temperature.

The fatty acid ester is preferably a fatty acid ester having a melting point of 80 ° C. or lower, more preferably a fatty acid ester that is liquid at room temperature and has a melting point of 25 ° C. or lower. Since the low melting point fatty acid ester is likely to exude on the surface of the molding layer, a raw roll having a molding layer containing the fatty acid ester is formed, and the fatty acid ester exuding on the surface is transferred to the back surface of the flexible support. Thus, a lubricant layer can be formed. In particular, a fatty acid ester having a melting point of 25 ° C. or less has a large effect of reducing the friction coefficient and more easily oozes onto the surface of the molding layer by aging. It can be transferred efficiently. For this reason, if the said low melting-point fatty acid ester is used, it will become unnecessary to form a lubricant layer by another process, and a brightness improvement sheet | seat can be manufactured further cheaply.

  Specific examples of fatty acid esters having a melting point of 80 ° C. or lower include oleyl oleate, myristyl oleate, 2-ethylhexyl oleate, methyl stearate, butyl stearate, stearyl stearate, octyl myristate, and lauric acid. Examples include methyl, isopropyl myristate, isopropyl palmitate, stearic acid monoglyceride, palmitic acid monoglyceride, oleic acid monoglyceride, ethyl oleate, and pentaerythritol tetrastearate. These may be used alone or in combination. Among these, oleyl oleate, butyl stearate, octyl myristate, isopropyl myristate, monoglyceride stearate and monoglyceride palmitate having a melting point of 25 ° C. or lower are preferred, and stearin having a low melting point and a low coefficient of friction can be obtained. Particularly preferred is butyl acid.

  Specific examples of fatty acids include hexanoic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, icosanoic acid, oleic acid, linoleic acid, and the like. These may be used alone or in combination. Among these, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid and icosanoic acid having a melting point of 25 to 80 ° C. are preferable, and myristic acid, palmitic acid and stearic acid having a melting point of 50 to 70 ° C. Is more preferable. The fatty acid is excellent in reducing the friction coefficient in a low temperature environment.

  When both the fatty acid ester and the fatty acid are contained in the molding layer, a fatty acid having a melting point that is 25 ° C. higher than the melting point of the fatty acid ester is more preferable. By using a fatty acid ester having a difference in melting point and a fatty acid in combination, excellent scratch resistance can be obtained under a wide temperature environment regardless of whether the temperature is low or high. In this case, the ratio between the fatty acid ester and the fatty acid in the molding layer is preferably 1: 9 to 9: 1, more preferably 8: 2 to 3: 7, and 8: 2 to 6: 4 in terms of mass ratio. Further preferred.

  In addition to fatty acids, suitable lubricants that can be used in combination with fatty acid esters include caproic acid amide, capric acid amide, lauric acid amide, palmitic acid amide, behenic acid amide, oleic acid amide, linoleic acid amide, and methylene bis. Aliphatic amides such as stearic acid amide; Silicone compounds such as silicone oil and modified silicone oil; Aliphatic alcohols such as stearyl alcohol and myristyl alcohol; Hydrocarbon compounds and the like.

  Examples of the active energy ray-curable resin include resins that are cured by irradiation with active energy rays such as ultraviolet rays, infrared rays, visible rays, X-rays, and electron beams. For example, a resin mainly composed of polymerizable monomers and oligomers can be used. Among such polymerizable monomers and oligomers, acrylic monomers and oligomers are preferred because there are many types and a wide range of options. The active energy ray-curable resin preferably has a viscosity at 25 ° C. of 10 to 600 mPa · s. If the viscosity is less than 10 mPa · s, the amount of the monofunctional monomer used to control this viscosity increases, and the properties of the molded layer may deteriorate, such as the curability being lowered and the molded layer becoming brittle. is there. If the viscosity exceeds 600 mPa · s, the resin may not smoothly enter the pattern of the molding roll when the resin layer is brought into contact with the molding roll, and defects such as entrapment of bubbles may occur.

  The active energy ray-curable resin preferably contains a monofunctional vinyl monomer or monofunctional (meth) acrylic monomer and a polyfunctional (meth) acrylic monomer (oligomer). In general, polyfunctional monomers (oligomers) are dominant in the cured product characteristics. The monofunctional monomer is used as a diluent for adjusting the viscosity. However, the lower the viscosity of the active energy ray-curable resin, the more difficult it is to secure the mechanical properties of the molding layer.

  Specific examples of the monofunctional vinyl monomer and the monofunctional (meth) acrylic monomer include, for example, vinylpyrrolidone, vinylformamide, acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, hydroxyethyl (meth) acrylate, and dimethylacrylamide. , Isobornyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, acryloylmorpholine , Phenoxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinic acid, 2 Acryloyloxyethyl-2-hydroxyethyl phthalate, 2-acryloyloxyethyl acid phosphate, and the like. These may be used alone or in combination. Acrylic monomers are preferred to methacrylate monomers from the viewpoint of curability. Since these monomers have a low viscosity, a low-viscosity resin solution can be obtained. Further, since these monomers have a heterocyclic ring, a functional group such as an amide group, a hydroxyl group, and a methoxy group, it is possible to improve the adhesion of the molded layer to the flexible support after curing. Among these, in terms of viscosity, curability, hardness, adhesion, and refractive index, vinylpyrrolidone, dimethylacrylamide, acryloylmorpholine, tetrahydrofurfuryl acrylate, hydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl-2-hydroxyethylphthalic acid is more preferred. In particular, 2-hydroxy-3-phenoxypropyl acrylate and 2-acryloyloxyethyl-2-hydroxyethylphthalic acid, which are well balanced in terms of viscosity, curability, hardness, adhesion, and refractive index, are preferable.

  Specific examples of the polyfunctional (meth) acrylic monomer (oligomer) include 2,2-bis [4- (acryloxyethoxy) phenyl] propane and 2,2-bis [4- (acryloxydiethoxy). ) Phenyl] propane, 2,2-bis [4- (acryloxypolyethoxy) phenyl] propane, 2,2-bis [4- (acryloxypropoxy) phenyl] propane, dimethyloltricyclodecane diacrylate, 2- Hydroxy-3- (meth) acryloyloxypropyl tri (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (Meth) acrylate, pentaerythritol tetra (meth) a Relate, dipentaerythritol hexa (meth) acrylate. These may be used alone or in combination. Examples of commercially available polyfunctional (meth) acrylic oligomers include Kyoeisha Chemical Co., Ltd. AH-600, UA306H, Shin-Nakamura Chemical Co., Ltd. U-4HA, U-6HA, U-6LPA, and the like. These monomers (oligomers) can impart hardness after curing or promote curability. Among these, 2,2-bis [4- (acryloxyethoxy) phenyl] propane, which is a polyfunctional (meth) acrylic monomer (oligomer) containing a diacrylate or dimethacrylate having a bisphenol A skeleton as a main component, 2,2-bis [4- (acryloxydiethoxy) phenyl] propane, 2,2-bis [4- (acryloxypolyethoxy) phenyl] propane, 2,2-bis [4- (acryloxypropoxy) phenyl Propane is preferred. Since the polyfunctional (meth) acrylic monomer (oligomer) having the bisphenol A skeleton is excellent in moldability at the time of molding the resin layer, a molding layer having a fine uneven pattern can be formed with high accuracy. Moreover, the said resin is excellent in the dispersibility of fatty acid ester and a fatty acid. Furthermore, fatty acid esters and fatty acids tend to exude on the surface of the molding layer in the molding layer containing the resin. For this reason, fatty acid ester and a fatty acid can be efficiently transcribe | transferred from the shaping | molding layer to the back surface of a flexible support body by aging. In terms of refractive index, 2,2-bis [4- (acryloxyethoxy) phenyl] propane, 2,2-bis [4- (acryloxydiethoxy) phenyl] propane, 2,2-bis [4- ( Acryloxypolyethoxy) phenyl] propane and 2,2-bis [4- (acryloxypropoxy) phenyl] propane are preferred. From the viewpoint of curability and hardness, tri- or higher functional pentaerythritol triacrylate, dipentaerythritol hexaacrylate, and acrylic oligomer are preferable.

  The mixing ratio of the monofunctional vinyl monomer or monofunctional (meth) acrylic monomer and the polyfunctional (meth) acrylic monomer (oligomer) is not particularly limited as long as the viscosity of the active energy ray-curable resin is 10 to 600 mPa · s. However, 10: 90-80: 20 are preferable by mass ratio. When the mass ratio of the monofunctional monomer is less than 10, the resin viscosity increases, the resin does not smoothly enter the pattern on the molding roll, and the transferability tends to deteriorate. When the mass ratio of the monofunctional monomer is larger than 80, the molding layer tends to be brittle. The active energy ray-curable resin preferably has a flash point of 70 ° C. or higher. The content of the active energy ray-curable resin in the molding layer is not particularly limited as long as the resin is contained as a main component, but is preferably 85 to 99% by mass, and 95 to 99% by mass with respect to the entire molding layer. Is more preferable.

  In addition to the above monomers, conventionally known general monomers and oligomers may be used for the active energy ray-curable resin. Moreover, you may use general purpose resin, an organic solvent, a photoinitiator, a sensitizer, a promoter, a leveling agent, a mold release agent, a coloring material, a filler, etc. as needed. When using an organic solvent, it is preferable to provide a drying step for removing the organic solvent after forming the resin layer. The need for a photoinitiator depends on the type of active energy ray. In particular, when an ultraviolet ray or a visible ray is used for the curing reaction as an active energy ray, a photoinitiator is required. Moreover, when irradiating an active energy ray through a flexible support body, it is preferable to use the photoinitiator according to the wavelength of the active energy ray which permeate | transmits a flexible support body. For example, when a polyethylene terephthalate film or a polyethylene naphthalate film is used as the flexible support, it does not overlap with the absorption wavelength of each flexible support such as Irgacure 369, 819, 907 (Ciba Geigy). It is possible to use a photoinitiator that absorbs in any wavelength region. In particular, it is preferable to use Irgacure 907 in combination with 2,4-diethylthioxanthone or 2-chlorothioxanthone because curing of the active energy ray-curable resin can be promoted. Although the quantity of a photoinitiator is based also on the kind of resin and photoinitiator to be used, it is 0.5-5 mass% normally with respect to the total amount of resin and a photoinitiator.

  The molding layer containing the active energy ray-curable resin and the lubricant as described above preferably has a pencil hardness of B or higher from the viewpoint of scratch resistance.

The lubricant layer 4 on the back surface of the flexible support 2 contains 0.06 to 9.5 mg / m ^{2 of} lubricant, preferably 0.5 to 4.5 mg / m ² , more preferably 0.8 to Contains 4.5 mg / m ² . By forming the lubricant layer containing the lubricant on the back surface of the flexible support, the coefficient of friction can be reduced and the slipperiness can be improved. Further, if a molding layer containing a lubricant in the above range and a lubricant layer containing a certain amount of lubricant are formed, the friction coefficient can be lowered without causing sticking on both sides of the brightness enhancement sheet. . Furthermore, since the dust is slippery between the molded layer and a lubricant layer, are laminated brightness enhancement sheet in a state where the dust between the brightness enhancing sheet is interposed, contact with the back surface of the molded layer and the flexible support Even when the back surface of the flexible support comes into contact with or slides on a hard foreign substance made of an acrylic resin or the like, damage to the brightness enhancement sheet can be reduced. When the amount of the lubricant is less than 0.06 mg / m ² , the lubrication performance is insufficient, the sliding property of the back surface of the flexible support cannot be sufficiently improved, and the scratch resistance is deteriorated. On the other hand, when the amount of the lubricant is more than 9.5 mg / m ² , the friction coefficient becomes high, sticking is likely to occur, and scratches are easily generated. In the case of a lubricant that is solid at room temperature, a large amount of lubricant tends to cause bleed-out and cause poor appearance. Note that the amount of the lubricant in the lubricant layer can be determined by washing the lubricant layer with hexane as in the case of the molded layer.

Further, in the brightness enhancement sheet of the present embodiment, when the content of the lubricant in the molding layer is Cs and the content of the lubricant in the lubricant layer is Cb, it is preferable that Cs is larger than Cb. Since the molding layer has fine irregularities and is easily damaged thereby, the lubricant content of the molding layer is preferably larger than that of the lubricant layer. On the other hand, since the lubricant layer has a smooth surface compared to the molded layer, if the lubricant content of the lubricant layer is too much than that of the molded layer, the front and back surfaces of the brightness enhancing sheets are stacked when stacked. It becomes easy to stick between. Further, the difference between Cs and Cb (Cs−Cb) preferably satisfies the following relationship.
0 mg / m ² <(Cs−Cb) ≦ 7.0 mg / m ²
When Cs is more than Cb and the difference between Cs and Cb (Cs−Cb) is 7.0 mg / m ² or less, the blocking property of the brightness enhancement sheet can be further improved. In addition, since the difference in the lubricant content between the molded layer and the lubricant layer is small within the range of the difference in the lubricant content, there is little difference in the optical characteristics of the two layers. For this reason, while being excellent in abrasion resistance, the brightness improvement sheet excellent in an optical characteristic can be obtained.

  As the lubricant for the lubricant layer, the same lubricant as that for the molding layer can be used. Among these, like the molding layer, the lubricant layer preferably contains at least one selected from the group consisting of fatty acid esters and fatty acids, more preferably contains at least fatty acid esters, and includes fatty acid esters and fatty acid esters. More preferably, both are contained. Moreover, as said fatty acid ester, the fatty acid ester which has melting | fusing point of 80 degrees C or less is preferable from the same reason as a shaping | molding layer, and the fatty acid ester which has melting | fusing point of 25 degrees C or less is more preferable. Moreover, as a fatty acid, the fatty acid which has 25-80 degreeC melting | fusing point is preferable, and the fatty acid which has 50-70 degreeC melting | fusing point is more preferable. Furthermore, when both the fatty acid ester and the fatty acid are contained, a fatty acid having a melting point higher by 25 ° C. or more than the melting point of the fatty acid ester is preferable. In this case, the ratio between the fatty acid ester and the fatty acid in the lubricant layer is preferably 1: 9 to 9: 1, more preferably 8: 2 to 3: 7, and 8: 2 to 6: 4 in terms of mass ratio. Is more preferable. When forming the lubricant layer without transferring the lubricant from the molded layer to the back surface of the flexible support, the lubricant in the lubricant layer is a different type of lubricant from the lubricant in the molded layer. May be. When the lubricant layer is formed by transferring the lubricant from the molding layer to the back surface of the flexible support, a lubricant layer containing the same type of lubricant as the lubricant of the molding layer can be formed. .

  The lubricant layer may contain other additives in addition to the lubricant as long as it does not affect the slipperiness. However, in consideration of scratch resistance, a lubricant layer containing substantially only a lubricant is preferable, and a lubricant layer consisting only of a lubricant is more preferable.

The static friction coefficient between the molding layer and the lubricant layer of the present embodiment is preferably 0.90 or more. When the static friction coefficient is 0.90 or more, the brightness enhancement sheet is difficult to move when a large number of brightness enhancement sheets are stored and transported in a stacked manner. The dynamic friction coefficient between the molding layer and the lubricant layer is preferably 0.90 or less. When the dynamic friction coefficient is 0.90 or less, even if the molding layer and the lubricant layer are rubbed, the molding layer and the lubricant layer are slid with low friction by the lubricant. For this reason, generation | occurrence | production of the damage | wound at the time of a preservation | save and conveyance of a brightness improvement sheet | seat can be prevented.

Next, the manufacturing method of the brightness enhancement sheet of the present embodiment will be described. In producing the brightness enhancement sheet, first, a resin solution containing an active energy ray-curable resin and a lubricant is prepared. In order to form a lubricant layer on the back surface of the flexible support, a lubricant solution containing a lubricant is prepared separately from the resin solution, and a molding layer containing an active energy ray-curable resin and a lubricant is formed. Before or after formation, the lubricant solution may be applied to the back surface of the flexible support to form a lubricant layer. However, if the lubricant layer is formed by transferring the lubricant from the molding layer, the preparation of the lubricant solution becomes unnecessary, and the lubricant layer forming step of applying the lubricant solution on the flexible support is performed. It is not necessary to perform it separately. Furthermore, when a solid lubricant is used at room temperature, a lubricant layer cannot be directly formed on the back surface of the flexible support. Therefore, a lubricant solution in which a solid lubricant is dissolved in a solvent is used as the flexible support. In order to remove the solvent, it is necessary to dry the coating solution, but according to the transfer from the molding layer, there is no need to provide such a lubricant layer forming step. Therefore, the manufacturing cost can be further reduced. Therefore, in the following, a method for forming a lubricant layer by using a resin solution containing an active energy ray-curable resin and a lubricant and transferring the lubricant from the molded layer to the back surface of the flexible support will be described. .

When preparing a resin solution containing an active energy ray-curable resin and a lubricant, it is preferable to adjust the content of the lubricant in the resin solution according to the type and melting point of the lubricant. For example, when a fatty acid ester having a relatively high melting point of 60 ° C. or higher is used, the lubricant has a lower mobility in the molding layer than a low melting point fatty acid ester, and the flexible support is formed from the molding layer. Therefore, the content of the lubricant is preferably 0.5 to 15% by mass with respect to the resin component (including the total amount when a photoinitiator is used). On the other hand, when a fatty acid ester having a relatively low melting point of 25 ° C. or less, which is a suitable lubricant, is used, the lubricant has a high mobility in the molding layer and is likely to ooze out on the surface of the molding layer. Thus, the lubricant can be efficiently transferred to the back surface of the flexible support. For this reason, 0.01-5 mass% is preferable with respect to resin component whole quantity (when using a photoinitiator, the total amount is included), and, as for content of a lubricant, 0.5-3 mass% is more. preferable. If the amount of lubricant is less than the amount of lubricant, the amount of lubricant in the molding layer is reduced, the amount of lubricant transferred is reduced, the coefficient of friction on both sides of the brightness enhancement sheet is increased, and the scratch resistance is increased. There is a tendency to deteriorate. When the amount is larger than the amount of the lubricant, the amount of the lubricant in the molding layer increases, and the amount of the lubricant to be transferred increases, which tends to cause sticking. In addition, when a solid lubricant is used at room temperature, bleeding out occurs and the appearance is liable to be poor.

FIG. 2 is a schematic configuration diagram illustrating an example of a brightness enhancement sheet manufacturing apparatus according to the present embodiment. As shown in FIG. 2, this manufacturing apparatus includes a transport unit 10 having a delivery roll 10 a and a take-up roll 10 b, and a resin layer 5 containing an active energy ray-curable resin and a lubricant on a flexible support 2. It has a resin layer forming part 20 for forming, and a transfer part 30 for molding a predetermined uneven pattern on the resin layer 5 and curing the molded resin layer 5. The transfer unit 30 is disposed in a sealed box (not shown) in order to cure the resin layer 5 in a nitrogen gas atmosphere (for example, an oxygen concentration of 300 ppm or less).

  As shown in FIG. 2, first, the resin layer forming unit 20 contains the active energy ray-curable resin and the lubricant on the flexible support 2 with a constant supply amount from the coating means 21 made of a coater or the like. The resin solution is supplied, and an uncured resin layer 5 is formed on one surface of the flexible support 2. Examples of the coating method include conventionally known roll coating methods, gravure coating methods, die coating methods, dip coating methods, curtain coating methods, and the like. As long as the application means 21 is before the molding of the resin layer 5, the place where the application means 21 is particularly arranged is not limited. For example, as shown in FIG. 3, the applying means 21 may be disposed on the forming roll 31.

  Next, the flexible support 2 on which the resin layer 5 is formed is conveyed to the transfer unit 30. This transfer unit 30 is active on the molding roll 31 for molding the concave / convex pattern on the resin layer 2, the nip roll 32 for pressing the flexible support 2 against the molding roll 31, and the resin layer 5 on which the concave / convex pattern is molded. Irradiation means 34 for irradiating the energy ray E to cure the resin layer 5, a backup roll 33, and a shielding plate 35 for preventing the active energy ray E from diffusing.

  In the transfer unit 30, the conveyed flexible support 2 is in contact with a molding roll 31 having a resin layer 5 having an emboss pattern (not shown) on the surface, and is opposite to the side on which the resin layer 5 is formed. The flexible support 2 is supplied between the forming roll 31 and the nip roll 32 so that the back surface of the flexible support 2 is in contact with the nip roll 32. The resin layer 5 is pressed against the molding roll 31 from the flexible support 2 side by the nip roll 32, and the embossed pattern on the molding roll 31 is transferred to the resin layer 5, whereby the uneven pattern is molded into the resin layer 5. . The resin layer 5 is cured by irradiating the molded resin layer 5 with active energy rays E from the irradiation means 34. As long as the irradiation means 34 can harden the resin layer 5, the place in particular will not be restrict | limited. For example, as shown in FIG. 4, an irradiation unit 34 may be disposed in the forming roll 31. In this case, as the forming roll 31, a resin roll that transmits the active energy ray E is used. According to this method, even when the flexible support 2 is made of a material that does not transmit the active energy ray E, the resin layer 5 can be cured.

  The uneven pattern of the molding layer 3 is formed in various shapes according to the purpose and application. For example, the average interval (D) of the unevenness is 0.01 to 50 μm, the average height (H) of the unevenness is 0.01 to 50 μm, and the ratio between the average interval (D) of the unevenness and the average height (H) of the unevenness A concavo-convex pattern with (D / H) of 0.01 to 100 can also be formed. FIG. 5 is a schematic cross-sectional view illustrating the concavo-convex pattern formed on the molding layer of the present embodiment. In the figure, (a) shows a flat concavo-convex pattern with a constant interval, (b) shows a prism-shaped concavo-convex pattern with a constant interval, and (c) shows a random prism-shaped concavo-convex pattern.

Next, the raw fabric roll 6 is formed by winding the flexible support 2 on which the molding layer 3 is formed in a roll shape with the take-up roll 10b. Winding tension original fabric roll 6 is preferably from 0.01 to 1 kg / mm ^2, more preferably 0.05 to 0.5 / mm ^2, and most preferably between 0.1 and 0.3 kg / mm ^2. When the winding tension is less than 0.01 kg / mm ² , the contact between the molding layer 3 and the back surface of the flexible support 2 becomes insufficient, and the lubricant may not be sufficiently transferred, and the raw roll 6 is deformed. It becomes easy to do. When the winding tension is greater than 1 kg / mm ² , the molding layer 3 is strongly pressed, so that dust may adhere between the flexible supports 2 and the shape may be transferred to the molding layer 3.

  The raw roll formed as described above is preferably aged at 30 to 100 ° C. in order to transfer the lubricant in the molding layer to the back surface of the flexible support to form the lubricant layer. . The lubricant can be transferred from the molded layer to the back surface of the flexible support without aging, but by aging in the roll state, the lubricant in the molded layer can easily exude to the surface of the molded layer, A sufficient amount of lubricant can be transferred to the back surface of the flexible support in a short time. For this reason, the lubricant amount in the molding layer and the lubricant layer can be appropriately adjusted by changing the addition amount of the lubricant in the resin solution and the aging conditions. When the aging temperature is less than 30 ° C., although depending on the melting point of the lubricant, there is little movement of the lubricant in the molding layer, the amount of lubricant exudation is small, the transfer of the lubricant is apt to be insufficient, and the Aging is required. When the aging temperature is higher than 100 ° C., a large amount of the lubricant is transferred and sticking tends to occur, and the flexible support tends to be deformed. Aging may be performed for a long time as long as the temperature does not cause deformation of the flexible support, but considering productivity, it is usually 24 hours to 1 week, preferably 24 to 48 hours. .

The brightness enhancement sheet of the present embodiment can be produced by cutting the raw roll produced as described above into a predetermined length. Since the brightness enhancement sheet thus obtained has improved scratch resistance, it can be used in various applications. For example, a lens sheet having a fine lens such as a lenticular lens or a fly-eye lens, can be used as a prism sheet.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(Examples 1-14 and Comparative Examples 1-5)
Resin solutions having the compositions shown in Tables 1 to 3 were prepared. In the table, “parts” means “parts by mass”. In the preparation, the viscosity (25 ° C.) of the active energy ray-curable resin alone and the resin solution was measured with an E-type viscometer (rotation speed: 10 rpm) manufactured by Toki Sangyo. Moreover, the state (25 degreeC) of the prepared resin solution was confirmed visually.
In producing the original fabric roll, the production apparatus shown in FIG. 1 was used. First, in the resin layer forming part, a resin solution was applied onto a PET film (thickness: 188 μm, Ra: 0.01 μm, Rz: 0.3 μm) that is continuously conveyed to form a resin layer. Thereafter, in the transfer portion, the resin layer is formed by a molding roll having a lenticular-shaped uneven pattern rotating at the same speed as the conveyance speed of the flexible support (average unevenness interval (D): 40 μm, average height of unevenness ( H): 20 μm, D / H: 2), in a state where the resin layer is pressed against the forming roll, by irradiating ultraviolet rays (1000 mJ / cm ² ) from a high-pressure mercury lamp to cure the resin layer Then, a molding layer having an uneven pattern was formed. Next, a roll of the flexible support was wound up with a winding tension of 0.1 kgf / mm ² to prepare an original roll.

(Comparative Example 6)
A raw roll was prepared in the same manner as in Comparative Example 1 except that a flexible support having a back coat layer having a thickness of 5 μm on the back surface of the surface on which the molding layer was formed was used as the flexible support. . The back coat layer was formed by applying a resin solution containing only the same resin as the active energy ray curable resin of the molding layer to one surface of the flexible support and irradiating the coating film with ultraviolet rays.

About each original fabric roll of Examples 1-14 produced as mentioned above and Comparative Examples 1-6, after aging each for 48 hours on the conditions shown in Tables 1-3, it cut | judged to fixed length and each brightness | luminance An improvement sheet was produced.

(Comparative Example 7)
A sheet was cut out from the raw roll produced in the same manner as in Comparative Example 5, and 0.5% by mass of a butyl stearate solution (solvent: n-hexane) was added to the back surface of the surface on which the molding layer of this sheet was formed. After coating, it was dried to produce a brightness enhancement sheet.

The following evaluation was performed using each brightness improvement sheet produced as described above.

[Amount of fatty acid ester]
At 25 ° C., the front and back surfaces of the brightness enhancement sheet were washed with hexane, and the amount of fatty acid ester washed out from each side in the washing solution was measured. In Comparative Example 2, the amount of silicone compound was measured.

[Coefficient of friction]
The dynamic friction coefficient with respect to the polyethylene terephthalate film (Toyobo A4300) on each surface of the brightness enhancement sheet was measured at 25 ° C. and 50% RH. The measurement conditions were a load of 20 g / mm, a sliding distance of 50 mm, a sliding speed of 1000 mm / min, and a sliding frequency of 2 reciprocations.

[Pencil hardness]
The pencil hardness of the molded layer of the brightness enhancement sheet was measured according to JIS K5600-5-4 at 25 ° C. and 50% RH.

[Abrasion resistance]
10 brightness enhancement sheets are laminated with the front and back surfaces of the brightness enhancement sheet facing each other, and 1 g of acrylic beads (particle size: 1 to 3 μm) per 1 m ² are scattered between the brightness enhancement sheets, and then the outer periphery with tape. Was fixed to prepare a measurement sample. The measurement sample produced as described above was vibrated at a frequency of 10 to 100 Hz in the X, Y, and Z directions for 1 hour each using a vibration tester (G-5230NS, manufactured by Senken Co., Ltd.). Gravitational acceleration was performed with two types of 2G and 4G. After vibration, the measurement sample was opened, and both surfaces of the brightness enhancement sheet that had been in contact with the acrylic beads were visually observed.

[appearance]
A measurement sample was prepared by cutting the brightness enhancement sheet into a size of 13 cm × 15 cm. This measurement sample was placed on a flat metal plate, and the maximum values of the height of warpage from the metal plate and the height of undulation from the metal plate were measured. The case where both heights were 1 mm or less was set to 1, the case where any one height was 1-2 mm, 2, and the case where any one height was larger than 2 mm was set to 3.

[Blocking properties]
Ten brightness enhancement sheets are laminated with the front and back surfaces of the brightness enhancement sheet facing each other, and a measurement sample is prepared by placing a weight on the laminate so that the load is 30 kg / m ^2. The sample was stored for 24 hours in an environment of 40 ° C. and 80% RH. After storage, observe the state of sticking between the sheets when the brightness enhancing sheet is peeled off by hand, ○ that there is no sticking between the sheets, ○, that there is some sticking between the sheets, △, between the sheets Were stuck and the sheet was difficult to peel off was evaluated as x.

Tables 1 to 3 also show the conditions for producing the brightness enhancement sheet and the evaluation results. In addition, the symbol in a table | surface shows the following.
a) HPPA: 2-hydroxy-3-phenoxypropyl acrylate (monofunctional acrylic monomer, n = 1.526, 200 mPa · s (25 ° C.))
b) PEGA: Phenoxyethylene glycol acrylate (monofunctional acrylic monomer, n = 1.519, 10 mPa · s (25 ° C.))
c) HEA: 2-hydroxyethyl acrylate (monofunctional acrylic monomer, n = 1.447, 5 mPa · s (25 ° C.))
d) AEPP: 2,2-bis [4- (acryloxydiethoxy) phenyl] propane (bifunctional acrylic monomer, n = 1.543, 1500 mPa · s (25 ° C.))
e) NPGA: Neopentyl glycol diacrylate (bifunctional acrylic monomer, n = 1.450, 5 mPa · s (25 ° C.))
f) PETA: pentaerythritol triacrylate (trifunctional acrylic monomer, n = 1.485, 800 mPa · s (25 ° C.))
g) OO: oleyl oleate (melting point: <5 ° C.)
h) SB: butyl stearate (melting point: 21 ° C.)
i) SS: stearyl stearate (melting point: 66 ° C.)
j) BYK-377: BYK-377 manufactured by Big Chemie (silicone compound, melting point: 0 ° C. or less)

As shown in the above table, the resin solutions of the examples contain an active energy ray-curable resin and a fatty acid ester, but since the fatty acid ester is uniformly dispersed in the resin, a colorless and transparent resin solution is prepared. can do. Moreover, the brightness improvement sheet | seat of an Example forms a shaping | molding layer using the resin solution containing active energy ray-curable resin and fatty acid ester, and ageds a raw fabric roll at 30-80 degreeC after shaping | molding layer formation. Thus, it is understood that the fatty acid ester is efficiently transferred from the molding layer to the back surface of the flexible support, and a lubricant layer is formed. Then, the transfer of a fatty acid ester, a shaping layer having a fatty acid ester of 0.1~28.8mg / ^{m 2,} it can be seen that can form a lubricant layer having a fatty acid ester of 0.06~9.5mg / ^{m 2} . For this reason, all the brightness enhancement sheets have a low coefficient of friction on both sides, improved slipperiness, and excellent scratch resistance. In particular, the brightness enhancement sheet produced using butyl stearate as the fatty acid ester has lower frictional resistance on both sides and is more slippery than the brightness enhancement sheet produced under the same conditions using other fatty acid esters. It turns out that it is excellent. Furthermore, in the embodiment, it is possible to transfer to the back surface of the flexible support a fatty acid ester from the forming layer by aging of 30 to 80 ° C., it can be seen that little brightness improvement over the sheet warp and waviness are obtained. In particular, in an example in which the aging temperature is 30 to 60 ° C., it is possible to obtain a brightness enhancement sheet with extremely little warpage and undulation. Furthermore, it can be seen that the brightness-enhancing sheet having a molding layer with a greater amount of lubricant than that of the lubricant layer and a difference of 6.4 mg / m ² or less is excellent in scratch resistance and blocking properties. .

On the other hand, the brightness enhancement sheet of the comparative example in which the molded layer does not contain a fatty acid ester has a high friction coefficient and is inferior in scratch resistance. Moreover, in the comparative example using the resin solution containing the silicone type compound which has lubricating performance, white turbidity occurred at the time of resin solution preparation, and the uniform resin solution was not able to be formed. Further, it can be seen that the brightness enhancement sheet of this comparative example contains a large amount of silicone compound on both sides. This is presumably because the silicone compound is not uniformly dispersed in the active energy ray-curable resin and the silicone compound is unevenly distributed near the surface of the molding layer. For this reason, the coefficient of friction increases as the measurement limit is exceeded, and the scratch resistance decreases. Further, even in a brightness enhancement sheet having a molding layer formed using a resin solution containing a fatty acid ester, if the amount of the fatty acid ester in the molding layer or the lubricant layer is too much or too little, the scratch resistance is sufficient. It turns out that it is not improved. Further, the brightness enhancement sheet of the comparative example provided with the backcoat layer containing the active energy ray curable resin had a high friction coefficient and was damaged when the vibration conditions were severe.

(Examples 15 to 16)
Resin solutions having the compositions shown in Table 4 were prepared, and brightness enhancement sheets were produced in the same manner as in Example 1.

Using the produced brightness enhancement sheet, the total amount of fatty acid ester and fatty acid, dynamic friction coefficient, pencil hardness, scratch resistance, and appearance were evaluated in the same manner as in the above Examples. In addition, the ratio (mass ratio) of fatty acid ester and fatty acid was measured by gas chromatography. Furthermore, the scratch resistance in the following cycle tests was evaluated using these brightness enhancement sheets and the brightness enhancement study sheet prepared in Example 2.

[Cycle test]
10 brightness enhancement sheets are laminated with the front and back surfaces of the brightness enhancement sheet facing each other, and 1 g of acrylic beads (particle size: 1 to 3 μm) per 1 m ² are scattered between the brightness enhancement sheets, and then the outer periphery with tape. Was fixed to prepare a measurement sample. The measurement sample produced as described above was vibrated at a frequency of 10 to 100 Hz in a cycle temperature environment in the X, Y, and Z directions using a vibration testing machine (G-5230NS, manufactured by Senken Co., Ltd.). The cycle condition was 25 ° C. for 3 hours → 60 ° C. for 3 hours → 25 ° C. for 3 hours → −20 ° C. for 3 hours, and this condition was repeated for 4 cycles. Moreover, gravitational acceleration was performed in two types, 2G and 4G. After vibration, the measurement sample was opened, and both surfaces of the brightness enhancement sheet that were in contact with the acrylic beads were visually observed. The case where there was no flaw was evaluated as ◯, and the case where there was a flaw was evaluated as x.

Table 4 shows these results. In addition, the symbol in a table | surface is the same as that of Table 1, and RA and SA show the following.
k) RA: Lauric acid (mp: 44 ° C.)
l) SA: Stearic acid (mp: 70 ° C.)

As shown in the above table, it can be seen that a resin solution having no cloudiness can be prepared even when a fatty acid ester and a fatty acid are used in combination as a lubricant. In addition, by forming a molding layer using a resin solution containing an active energy ray-curable resin, a fatty acid ester, and a fatty acid, and aging the raw roll after the molding layer is formed, the flexible support is removed from the molding layer. It can be seen that the fatty acid ester and the fatty acid are transferred to the back surface to form a lubricant layer. And it turns out that the friction coefficient of both surfaces is reduced and slipperiness is improved by forming the shaping | molding layer and lubricant layer containing fatty acid ester and a fatty acid. For this reason, these brightness improvement sheets are excellent in abrasion resistance.

  Furthermore, it can be seen that by forming a molding layer and a lubricant layer containing both a fatty acid ester and a fatty acid, the scratch resistance is further improved in a cycle test from a low temperature to a high temperature. In particular, when a fatty acid having a relatively high melting point of about 70 ° C. and having a melting point 25 ° C. higher than the melting point of the fatty acid ester is used in combination with the fatty acid ester, this effect is great.

It is a schematic sectional drawing which shows an example of the brightness improvement sheet | seat which concerns on embodiment of this invention. It is a schematic block diagram which shows an example of the manufacturing apparatus for manufacturing the brightness improvement sheet | seat which concerns on embodiment of this invention. It is a schematic block diagram which shows another example of the manufacturing apparatus for manufacturing the brightness improvement sheet | seat which concerns on embodiment of this invention. It is a schematic block diagram which shows another example of the manufacturing apparatus for manufacturing the brightness improvement sheet | seat which concerns on embodiment of this invention. It is a schematic sectional drawing which illustrates the uneven | corrugated pattern of a shaping | molding layer, (a) shows the flat uneven | corrugated pattern of fixed space | interval, (b) shows the prism-shaped uneven | corrugated pattern of fixed space | interval, (c) is random A prismatic uneven pattern is shown.

Explanation of symbols

1 Brightness improving sheet 2 Flexible support 3 Molding layer 4 Lubricant layer 5 Resin layer 6 Original roll 31 Molding roll E Active energy ray

Claims (11)

A flexible support;
On the surface of the flexible support, a molding layer containing an active energy ray-curable resin and 0.02 to 30.0 mg / m ² of a lubricant,
An optical sheet having a lubricant layer containing 0.02 to 10.0 mg / m ² of lubricant on the back surface of the flexible support.   The optical sheet according to claim 1, wherein the molding layer contains more lubricant than the lubricant layer. The difference (Cs-Cb) between Cs and Cb satisfies the following relationship, where Cs is the lubricant content of the molding layer and Cb is the lubricant content of the lubricant layer. The optical sheet described.
0 mg / m ² <(Cs−Cb) ≦ 7.0 mg / m ²   The optical sheet according to any one of claims 1 to 3, wherein the molding layer and the lubricant layer contain at least one selected from the group consisting of a fatty acid ester and a fatty acid as the lubricant.   The optical sheet according to claim 4, wherein the fatty acid ester has a melting point of 80 ° C. or less.   The optical sheet according to claim 4, wherein the fatty acid ester has a melting point of 25 ° C. or lower.   The optical sheet according to any one of claims 4 to 6, wherein the fatty acid has a melting point of 25 to 80 ° C.   The optical sheet according to any one of claims 4 to 7, wherein the fatty acid has a melting point higher by 25 ° C or more than the melting point of the fatty acid ester.   The optical sheet according to any one of claims 1 to 8, wherein the active energy ray-curable resin contains a diacrylate or dimethacrylate having a bisphenol A skeleton as a main component. A molding roll is brought into contact with a resin layer containing an active energy ray-curable resin provided on the surface of a flexible support that is continuously conveyed and 0.01 to 5% by mass of a lubricant with respect to the total amount of resin components. Mold the resin layer,
The resin layer is cured by irradiating the molded resin layer with active energy rays to form a molded layer,
The flexible support on which the molding layer is formed is wound into a roll to form a raw roll,
The manufacturing method of the optical sheet which ages the said original fabric roll at the temperature of 30-100 degreeC.   The method for producing an optical sheet according to claim 10, wherein the resin layer contains at least a fatty acid ester having a melting point of 25 ° C. or less as the lubricant.

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