JP2009210911A - Optical laminated sheet and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated sheet for optical purposes, which is excellent in flaw resistance with high transmittance, and can prevent adhesion of foreign matter by dust or the like. <P>SOLUTION: An easily adhesive layer 12 is formed on one surface of a support 11 formed of biaxially-stretched polyester. A protective layer 13 is formed on the other surface of the support 11. The protective layer 13 includes: a binder that is a water-soluble or water-dispersive polymer; organic fine particles; a betaine-based antistatic agent having an imidazolium skeleton; and a lubricant. According to this, a laminated sheet excellent in flaw resistance with high transparency, and which can prevent adhesion of foreign matter by dust or the like can be obtained. Luminance unevenness decreases by using the laminated sheet for a diffusion sheet. Further, front luminance rate increases by using it for a prism sheet. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical laminated sheet, and in particular, an optical laminated sheet having high transmittance and excellent optical properties used for optical functional members such as a diffusion sheet and a prism sheet, and the optical functional member as a constituent member The present invention relates to an image display device such as a liquid crystal display, a plasma display, an organic EL display, a surface electric field display (SED), and a CRT display.

  As an image display device realizing high image quality, a liquid crystal display device (LCD), a plasma display device (PDP), an organic EL display device and the like are attracting attention. Above all, LCDs are thinner and lighter than other image display devices, so the demand for such devices as large-screen TVs and portable electronic devices is growing rapidly. LCDs consist mainly of a liquid crystal cell in which a special liquid is sealed between glass plates and a polarizing plate. By applying a voltage to the liquid crystal cell and changing the direction of the liquid crystal molecules, the transmittance of light is increased or decreased to form an image. Display. In addition, LCDs have prism sheets, light diffusion sheets, antireflection sheets, hard coats to prevent reflection and scattering of light and protect polarizing plates in order to ensure high image quality. An optical sheet having an optical function such as a sheet is used. For example, Patent Document 1 describes in detail a light diffusion sheet.

  In general, an optical sheet is mainly a laminated sheet in which an optical functional layer such as a light diffusing layer or a light diffusing layer, an antireflection layer, or a hard coat layer is provided on the surface of a support made of a transparent resin. Then, it is manufactured by applying a material for forming an optical functional layer on the surface of the support to be conveyed and drying it.

  Such a laminated sheet is required to have a high transmittance. Also, if there are foreign objects such as fine dust or scratches on the surface, the contrast of the display will decrease or luminance unevenness will occur and the image quality will deteriorate, so there will be as few foreign objects and scratches on the surface as possible. In addition, it is desirable that the surface is not easily foreign matter or scratched. However, when manufacturing a laminated sheet, foreign matter such as dust is applied to the surface of the support when a material is applied to the surface of the support, the laminated sheet is conveyed, or the completed laminated sheet is accumulated. Abrasion is likely to occur. In this case, a method is known in which fine particles are added to the optical functional layer to improve slipperiness and suppress the occurrence of scratches.

For example, Patent Document 2 discloses a laminated sheet having high transparency and reduced occurrence of luminance unevenness by providing an optical functional layer composed of a polymer composition containing polyester polyol or acrylic polyol and fine inorganic fine particles. Proposed. Patent Document 3 proposes a laminated sheet that has high transparency and is hardly damaged by providing a coating layer containing organic or inorganic fine particles, a binder, and a slipping agent on at least one surface of a support. ing.
JP 2006-095980 A JP 2004-004598 A Japanese Patent Application No. 2005-354908

However, Patent Document 2 can reduce brightness unevenness caused by the occurrence of bending or discoloration by receiving heat, ultraviolet rays, or the like, but cannot reduce scratches caused during transportation. In addition, since a large amount of fine particles are added, there is a possibility that scratches may occur due to a decrease in transparency or floating of the fine particles. In Patent Document 3, since only the scratch resistance on the side where the optical functional layer is provided can be improved, improvement of scratch resistance on the other surface of the support remains as a problem.
Further, both the inventions cannot reduce the occurrence of scratches due to the adhesion of foreign matters such as dust and the friction of foreign matters.

  Therefore, the present invention provides an optical laminated sheet and an image display device that have high transmittance, are less likely to adhere foreign matter such as dust on the surface, are not easily scratched, and are excellent in optical characteristics such as transmittance and luminance. Objective.

  The optical laminate sheet of the present invention is a biaxially stretched support made of polyester, an optical functional layer disposed on one surface of the support, and disposed on the other surface of the support. Alternatively, a water-dispersible polymer binder, organic fine particles, and a protective layer containing a betaine antistatic agent having an imidazolium skeleton are provided.

  The organic fine particles are preferably made of at least one of polystyrene and polymethyl methacrylate. Furthermore, the average particle size of the organic fine particles is preferably 0.05 μm or more and 20.0 μm or less.

The binder which is a water-soluble or water-dispersible polymer is preferably made of at least one of a polyester resin, a polyurethane resin and an acrylic resin.

  The protective layer includes a water-soluble or water-dispersible polymer binder and a fine particle-containing layer containing organic fine particles, and a water-soluble or water-dispersible polymer binder and imidazolinium skeleton on the fine particle-containing layer. It is preferably a two-layer laminate comprising a surface layer containing a betaine antistatic agent.

  The image display device of the present invention includes any one of the above laminated sheets.

  According to the laminated sheet of the present invention, a binder that is a water-soluble or water-dispersible polymer, organic fine particles, and the other surface of a biaxially stretched polyester provided with an easy-adhesion layer as an optical sheet, Since a protective layer containing a betaine antistatic agent having an imidazolium skeleton is provided, for example, when a light diffusing layer is provided as an optical functional layer on an easy-adhesive layer, the main component of the LCD backlight system And can be used as a diffusion sheet having excellent scratch resistance on the light side. Further, since the antistatic property can be improved by the antistatic agent, it is possible to reduce the adhesion of foreign matter due to dust and the like, and it is possible to simultaneously realize the scratch resistance and the prevention of foreign matter adhesion. If a prism layer is provided as an optical functional layer on the easy adhesion layer by adding fine particles having an appropriate particle size, a prism sheet having excellent transmittance and front luminance can be provided. Accordingly, a laminated sheet having high transparency and excellent scratch resistance can be provided, and a high-quality image display device can be provided by using the laminated sheet.

  Hereinafter, the laminated sheet according to the present invention will be described in detail with reference to embodiments. However, this embodiment is one of the preferred applications according to the present invention, and does not limit the present invention.

  FIG. 1 is a cross-sectional view schematically showing an example of a laminated sheet 10 according to the present invention. The laminated sheet 10 includes a support 11 made of polyester, an easy adhesion layer 12 provided on one surface of the support 11, and a protective layer 13 provided on the other surface of the support 11. In addition to the configuration shown in FIG. 1, as shown in FIG. 2, a laminated sheet 17 having a protective layer 16 having a two-layer structure of a fine particle-containing layer 14 and a surface layer 15 instead of the protective layer 13 having a single-layer structure. Alternatively, instead of the easy-adhesion layer 12 having a single-layer structure, an easy-adhesion layer having a laminated structure of an easy-adhesion first layer 18 and an easy-adhesion second layer 19 may be used.

[Support]
The polyester used for forming the support 11 is not particularly limited, and known polyesters that can be used for optical applications can be used. Specific examples include polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate. Polyethylene terephthalate is particularly preferable from the viewpoint of cost and mechanical strength.

  The support 11 of the present invention is preferably biaxially stretched. Biaxial stretching refers to stretching in both directions by regarding the width direction and the longitudinal direction of the support 11 as uniaxial. As a result, the molecular orientation in the two axes of the support 11 is sufficiently controlled, so that the mechanical strength is improved. The draw ratio is not particularly limited, but the draw ratio in one direction is preferably 1.5 to 7 times, more preferably 2 to 5 times. In particular, it is preferable to perform biaxial stretching with a stretching ratio per uniaxial direction of 2 to 5 times. Here, if the stretching ratio of the support 11 is less than 1.5 times, sufficient mechanical strength cannot be obtained. On the other hand, if the stretching ratio exceeds 7 times, it is difficult to obtain a uniform thickness.

  The thickness t1 (μm) of the support 11 is preferably 30 μm or more and 400 μm or less by controlling the draw ratio. More preferably, t1 is not less than 35 μm and not more than 350 μm. Such a support 11 is lightweight and excellent in handleability while having high transparency. However, if t1 is less than 30 μm, it is difficult to handle because it is too thin.On the other hand, if t1 exceeds 400 μm, it is too thick, which makes it difficult to reduce the size and weight of the image display device. Is unsuitable because it causes an increase in

[Easily adhesive layer]
The easy-adhesion layer 12 has a function of improving adhesion between the polyester surface and improving the adhesion between the optical functional layer provided thereon and the support 11. The easy-adhesion layer 12 is usually formed by applying a coating solution comprising a binder, a curing agent, and a surfactant to one surface of the polyester support. A slipping agent such as organic or inorganic fine particles or wax may be added to the easy adhesion layer 12 as necessary.

  The binder used for the easy-adhesion layer 12 is not particularly limited as long as it can improve the adhesion to the polyester support, but from the viewpoint of easy adhesion, one of polyester resin, polyurethane resin, acrylic resin, and styrene-butadiene resin. It is preferable to use the above. A water-soluble or water-dispersible binder is particularly preferable from the viewpoint of environmental load.

  The formation method of the easy-adhesion layer 12 is not particularly limited, and a known coating method can be appropriately selected according to the purpose. For example, a spin coater, a roll coater, a bar coater, a curtain coater and the like can be mentioned. In any of the methods, a solution containing a material for forming an easy-adhesion layer is applied to a desired surface and then dried to form a layer. Here, the drying method is not particularly limited, and a commonly used method can be appropriately selected. At this time, it is preferable that the drying temperature is 90 ° C. or higher and 210 ° C. or lower because the drying can be performed in a short time without damaging the optical functional layer or the like. More preferably, it is 110 ° C. or more and 200 ° C. or less. When the drying temperature is less than 90 ° C., the close contact with the support 11 is insufficient and the drying time may be long. On the other hand, if it exceeds 210 ° C., the deformation of the polyester support may be increased, which is not preferable. Also, in order to promote drying in a short time without causing thermal damage, the drying time is preferably 10 seconds to 5 minutes under an appropriate temperature condition, more preferably 20 seconds to 3 minutes. is there.

  The thickness t2 (μm) of the easy adhesion layer 12 can be controlled by adjusting the coating amount. In order to provide high transparency and excellent easy adhesion, t2 is preferably 0.01 μm or more and 5 μm or less. More preferably, t2 is 0.02 μm or more and 3 μm or less. Here, if t2 is less than 0.01 μm, it is too thin to develop easy adhesion, while if t2 exceeds 5 μm, it is difficult to maintain a uniform coating thickness surface quality. This is unsuitable because it causes an increase in manufacturing cost. The easy adhesion layer 12 may be a single layer or a multilayer of two or more layers. Here, in the case of multiple layers, the total film thickness is regarded as t2.

[Protective layer]
The protective layer 13 contains a binder, organic fine particles, and an antistatic agent. As the binder used for the protective layer 13, a water-soluble or water-dispersible polymer is used. As a film increasing aid, it may contain an organic solvent of 20% or less of the total solvent. However, when the organic solvent is contained in excess of 20%, the amount scattered in the atmosphere increases, which is not preferable in terms of environment and explosion protection. The type of polymer is not particularly limited as long as it is water-soluble or water-dispersible, but is preferably composed of at least one of a polyester resin, a polyurethane resin, and an acrylic resin. Particularly preferred is a polymer having a glass transition temperature of 40 ° C. or higher. When the glass transition temperature is less than 40 ° C., it is difficult to ensure sufficient scratch resistance because it softens at room temperature. Among the above-mentioned polymers, it is particularly preferable to use a polymer having a carboxyl group in the molecule because the adhesive strength at the interface with the support 11 can be improved. Moreover, the polymer used as a binder may be used individually by 1 type, and may mix and use 2 or more types. For example, when an acrylic resin polymer having a carboxyl group in the molecule and a polyester polymer are mixed and used, the protective layer 13 having excellent scratch resistance and high adhesive strength can be obtained. In addition, the molecular weight of a polymer is not specifically limited, What is normally utilized as a binder can be used.

  The material of the fine particles that can be used for the protective layer 13 is not particularly limited, but organic fine particles are preferable. When inorganic fine particles are used, there is a possibility of scratching the surface of another optical sheet to be superposed due to its high hardness. Examples of the organic fine particle material include polystyrene, polymethyl methacrylate, nylon resin, polyethylene resin, polypropylene resin, polyester resin, silicone resin, and benzoguanamine resin. Among these, polystyrene and polymethyl methacrylate are preferable because they are excellent in the effect of improving slipperiness and are low in cost.

Regardless of the material, the average particle size of the fine particles is preferably 0.05 μm or more and 20 μm or less. More preferably, it is 0.5 μm or more and 18 μm or less, and particularly preferably 1 μm or more and 15 μm or less. Thereby, the slipperiness can be improved while the fine particles are uniformly dispersed to ensure high transmittance. Here, if fine particles having an average particle size of less than 0.05 μm are used, the effect of improving the slipperiness is weak, whereas if fine particles having an average particle size of more than 20 μm are used, the fine particles may fall off the coating film. The possibility increases and it is unsuitable. Moreover, although the addition amount of microparticles | fine-particles also changes with average particle diameters, 0.1 mg / m < ² > or more and 1000 mg / m < ² > or less are preferable, More preferably, they are 0.5 mg / m < ² > or more and 800 mg / m < ² > or less. Here, if the amount of fine particles added is less than 0.1 mg / m ² , the effect of improving the slipping property is weak, whereas if it exceeds 1000 mg / m ² , the light diffusibility increases and the function of the optical functional layer increases. There is a risk of lowering. The particle diameter of the fine particles in the present invention refers to the diameter of a circle having the same area as the fine particles when the fine particles are photographed with a scanning electron microscope. The average particle diameter refers to the average value of the particle diameters obtained for any 50 fine particles.

  Use of monodisperse fine particles having a narrow particle size distribution is preferable in terms of quality maintenance because fine particles having a large particle size with a high possibility of dropping off are reduced. When monodisperse particles are used, an effect of improving the optical performance of the optical functional sheet to be used can be expected due to a homogeneous lens effect.

  The antistatic agent in the present invention refers to a substance that lowers the surface resistance of the protective layer of the laminated sheet. The antistatic agent is preferably a betaine compound having an imidazolium skeleton. Fatty acid salt-based and phosphoric acid-based anionic antistatic agents have a small effect of reducing the surface resistance, and therefore, it is necessary to increase the amount added to the binder, resulting in a decrease in film strength. Similarly, fatty acid-based and aliphatic amide-based nonionic antistatic agents are also less effective in reducing surface resistance. Cationic antistatic agents such as quaternary ammonium salts are effective in reducing surface resistance, but generally exhibit acidity, so the aqueous dispersion binder to be mixed is usually anionic, so it can be applied during mixing. The stability of the liquid may decrease, and the binder may aggregate. For example, when an imidazolium chloride and an acrylic resin latex having an ammonium acrylate group are mixed, the dispersion is broken and the binder is likely to agglomerate.

  The amount of the antistatic agent used in the present invention is preferably 1 to 50% by weight, particularly preferably 3 to 40% by weight, based on the solid content in the protective layer. When the addition amount is less than 1%, a sufficient decrease in surface resistance is not observed, and an antistatic effect cannot be expected. When the addition amount exceeds 50% by weight, the film hardness of the protective layer is lowered and the scratch resistance is lowered.

The surface resistance obtained by the addition of the antistatic agent of the present invention is designed on the premise of the temperature and humidity at which the laminated sheet of the present invention or the functional optical member using the same is used. In this case, the surface resistivity is preferably 10 ¹³ / □ or less, particularly preferably 10 ¹² / □ or less. When the surface resistivity exceeds 10 ¹³ / □, adhesion of dust due to electrification increases.

  The protective layer 13 of the present invention contains a binder which is a water-soluble or water-dispersible polymer, organic fine particles, and a betaine antistatic agent having an imidazolinium skeleton as essential components. You may add a crosslinking agent, surfactant, etc.

  As the cross-linking agent, epoxy-based, melamine-based, isocyanate-based, carbodiimide-based cross-linking agents can be used. The addition amount is preferably in the range of 1% to 50%, particularly preferably in the range of 5% to 40% with respect to the total solid content in the protective layer. If the addition amount is less than 1%, the film properties are not sufficiently improved by the crosslinking effect, and if it exceeds 50%, the film properties such as the film becomes brittle.

  As the surfactant, known anionic, nonionic, and cationic surfactants can be used. Surfactants are described in, for example, “Surfactant Handbook” (issued in 1960 by Ichiro Nishi, Koichiro Imai, Shozo Kasai, Sangyo Tosho Co., Ltd., 1960).

  The thickness t3 of the protective layer 13 is preferably 0.02 μm or more and 20 μm or less, and particularly preferably 0.05 μm or more and 15 μm. If t3 is less than 0.02 μm, the antistatic property, scratch resistance and fine particle holding power may be insufficient. On the other hand, if t3 exceeds 20 μm, the surface state may be deteriorated. The protective layer 13 may be a single layer, or two or more layers may be laminated. When two or more layers are laminated, it is preferable that the total thickness of all the layers satisfies the above range.

  As shown in FIG. 2, the protective layer 16 includes a water-soluble or water-dispersible polymer binder containing fine particles 14 and organic fine particles, and a water-soluble or water-dispersible polymer binder and imidazolinium thereon. It may be a two-layer laminate comprising a surface layer 15 containing a betaine-based antistatic agent having a skeleton. By separating the protective layer 16 into the fine particle-containing layer 14 and the surface layer 15, it is possible to further suppress the drop-off of the fine particles compared to the case of one layer. In addition, the amount of antistatic agent used to obtain the same surface resistance can be reduced.

  There are no particular restrictions on the method of applying the protective layer 13 of the present invention. As a coating method, known methods such as bar coater coating and slide coater coating can be used. The coating solvent used by mixing with the above-mentioned essential components is preferably water with a small environmental load. However, in order to improve the coating surface condition and improve the stability of the coating solution, methyl alcohol, isopropyl alcohol, methyl ethyl ketone, etc. Organic solvent solvents can be mixed and used.

  The application may be performed after the support 11 is stretched in the uniaxial direction or may be performed after the biaxial stretching. However, in order to enable recovery of the base ear after lateral stretching, it is preferable to apply after biaxial stretching.

(Optical function layer)
By providing the optical functional layer on the easy-adhesion layer 12 of the laminated sheet 10, an optical functional member having a desired optical function is formed. For the optical functional layer, a light diffusion layer, an antireflection layer, a prism layer, an antiglare layer, and the like are appropriately selected according to the purpose of use. This optical functional member is used for other display devices such as a PDP, an organic EL display, and a CRT display in addition to the LCD. Moreover, by forming an optical functional layer having excellent mechanical strength, such as a hard coat layer, it is possible to impart hardness without impairing the optical function, or to make it difficult to be stained.

  According to the present invention, a diffusion sheet 20 as shown in FIG. 3 can be easily formed as an example of an optical member. The diffusion sheet 20 includes a support 21 made of polyester, a light diffusion layer 22 formed on an easy adhesion layer 24 disposed on one surface of the support 21, and a support opposite to the light diffusion layer 22. And a protective layer 23 disposed on the other surface of the body 21. The thickness of each layer is designed to satisfy the range described in FIG.

  The light diffusion layer 22 contains a binder and fine particles. Here, scratch resistance during handling, solvent resistance for wiping off dirt and dirt on the surface, and sometimes the laminated sheet 11 is punched into a predetermined form, so high adhesion strength to the support 11 For the purpose of ensuring, it is preferable to contain a crosslinking agent. Note that the light diffusion layer 22 may be a single layer, or may have a laminated structure of two or more layers as desired. In the case of two or more layers, it is not necessary to form layers having the same optical function, and they can be selected as appropriate.

  The binder used for the light diffusion layer 22 is not particularly limited, and can be appropriately selected according to the purpose. As a suitable example, known polymers such as acrylic, polyester, and polyurethane can be used. Among them, it is preferable to use a homopolymer or copolymer containing at least one of acrylic acid ester and methacrylic acid ester as a monomer component because excellent optical properties and high transparency can be secured.

  Examples of the homopolymer or copolymer include (meth) acrylic resin, vinyl acetate resin, ethylene-vinyl acetate copolymer resin, vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer resin, butyral resin, and silicone resin. , Polyester resin, vinylidene fluoride resin, nitrocellulose resin, styrene resin, styrene-acrylonitrile copolymer resin, urethane resin, polyethylene, polypropylene, chlorinated polyethylene, rosin derivative and the like. These may be used alone or in combination of two or more. Among these, a (meth) acrylic resin is particularly preferable because it is less likely to dissolve or swell organic particles. Furthermore, it is preferable to use a polymer capable of reacting with the aforementioned crosslinking agent. For example, when the crosslinking agent is an isocyanate crosslinking agent, a polymer having a hydroxyl group, an amino group, a carboxyl group, or the like can be used. These binders may be used alone or in combination.

  The light diffusion layer 22 contains fine particles that act as a light diffusing agent for diffusing the transmitted light. The fine particles are not particularly limited and can be appropriately selected according to the purpose. Suitable specific examples include organic particles such as polymethyl methacrylate resin particles, melamine resin particles, polystyrene resin particles, and silicone resin particles. Can be mentioned. These may be used alone or in combination of two or more. These organic particles preferably have a crosslinked structure, and in particular, polymethyl methacrylate resin particles having a crosslinked structure are preferable.

  The average particle size of the fine particles is preferably 3 μm or more and 100 μm or less, and more preferably 5 μm or more and 25 μm or less. When the average particle size is less than 3 μm, the light diffusing ability becomes insufficient. On the other hand, if the average particle size exceeds 100 μm, the average particle size is too large, which may hinder the transmission of light, and it is difficult to fulfill the function as a light diffusing agent. Moreover, since the sedimentation rate of the fine particles in the coating liquid increases, the fine particles settle in the piping and buffer tank used for liquid feeding. Since the method for obtaining the average particle size is the same as described above, the description is omitted.

  The addition amount of the fine particles is preferably 100 parts by mass or more and 500 parts by mass or less, more preferably 200 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of the binder. If the addition amount of the fine particles is less than 100 parts by mass, the function as a light diffusing agent may not be achieved. On the other hand, if it exceeds 500 parts by mass, the fine particles may be difficult to disperse. In the present invention, other fine particles may be used in combination with the fine particles described above. For example, it is preferable to use silica, calcium carbonate, alumina, and zirconia having an average particle size of 1 μm or more and 5 μm or less for the polymethyl methacrylate resin particles of 10 μm or more and 25 μm. The addition amount of the fine particles used in combination is preferably 1% by mass or more and 20% by mass or less of the main component fine particles.

  The light diffusion layer 22 preferably contains a crosslinking agent for the purpose of imparting solvent resistance and adhesion to the support. As the crosslinking agent, epoxy, isocyanate, melamine, oxazoline, carbodiimide, or the like can be used. Especially, it is preferable to use an isocyanate type crosslinking agent from said objective. The content of the crosslinking agent in the light diffusion layer 22 is preferably 10 parts by mass or more, and more preferably 30 parts by mass or more and 400 parts by mass or less with respect to 100 parts by mass of the binder. If the content of the crosslinking agent is less than 10 parts by mass, the light diffusion layer 22 may be easily damaged. Further, when the mass of the crosslinking agent is a and the mass of the binder is b, a / b, which is the mass ratio of the crosslinking agent and the binder in the light diffusion layer 22, is preferably 1 or more and 20 or less, more preferably It is 3 or more and 15 or less, and particularly preferably 5 or more and 10 or less.

When forming the light diffusion layer 22, the solvent mixed with a material such as a binder is not particularly limited. Examples of suitable solvents include (a) ketones, (b) ethers, (c) alcohols, (d) esters, (e) polyhydric alcohol derivatives, (f) carboxylic acids, etc. Can do. These preferred specific examples are listed below together with the specific gravity (g / cm ³ ). The specific gravity is the ratio between the mass of the target substance and the mass of water of the same volume. Here, the specific gravity is written in parentheses after the compound name, and the unit description is omitted.

  (A) Examples of ketones include acetylacetone (0.975), cyclohexanone (0.945), methylcyclohexanone (0.921), acetone (0.791), diethylketone (0.816), methylethylketone (0.805), and methyl-n-butylketone (0.821). Methyl-n-propyl ketone (0.806), and the like.

  Examples of (b) ethers include 1,4-dioxane (1.039), tetrahydrofuran (0.889), and the like.

  (C) Examples of alcohols include cyclohexanol (0.949), 3-pentanol (1.046), 2-methylcyclohexanol (0.925), isopropyl alcohol (0.785), ethanol (0.791), and n-butanol (0.810). , T-butanol (0.787), 1-propanol (0.804), methanol (0.792) and the like.

  Examples of (d) esters include isoamyl formate (0.877), isobutyl formate (0.885), ethyl formate (0.917), butyl formate (0.892), propyl formate (0.901), hexyl formate (0.990), and benzyl formate (1.081). ), Methyl formate (0.987), allyl acetate (0.927), isoamyl acetate (0.871), isobutyl acetate (0.873), isopropyl acetate (0.877), ethyl acetate (0.901), 2-ethylhexyl acetate (0.827), cyclohexyl acetate (0.97) ), N-butyl acetate (0.876), s-butyl acetate (0.875), propyl acetate (0.887), methyl acetate (0.934), ethyl propionate (0.896), butyl propionate (0.877), methyl propionate (0.916) , Etc.

  (E) As polyhydric alcohol derivatives, for example, ethylene glycol monoethyl ether acetate (0.975), ethylene glycol monomethyl ether (0.964), ethylene glycol monomethyl ether acetate (1.009), ethylene glycol monomethoxymethyl ether (1.04), And propylene glycol monoethyl ether (0.898) and propylene glycol monomethyl ether (0.923).

  Examples of (f) carboxylic acids include isobutyric acid (0.948) and caproic acid (1.049).

  Among these, from the viewpoint of easy drying after coating, an organic solvent having a boiling point of 150 ° C. or lower is preferable, and methyl ethyl ketone, cyclohexanone, 1,4-dioxane, and ethylene glycol monomethyl ether acetate are particularly preferable.

  The diffusion sheet 20 as described above can be suitably used as a main constituent member of the backlight unit constituting the LCD. FIG. 4 is a perspective view showing an outline of a general backlight unit 30. FIG. In addition, in order to avoid the complexity of drawing, only the main structural members are shown, but actually, there are a plurality of other members. Among the members constituting the backlight unit 30, a plurality of lamps 35 are disposed inside a frame 33 having a reflection sheet 32 attached inside, and this serves as a light source for illuminating the liquid crystal cell. A diffusing plate 36 is installed immediately above the lamp 35, and a diffusing sheet 20 and a prism sheet 38 are sequentially disposed thereon. Each member is fixed while being sandwiched between the rear frame 33 and the front frame 39. The diffusion sheet 20 obtained by the present invention has an excellent light diffusion function and excellent scratch resistance on the surface of the support opposite to the light diffusion layer, and thus provides a high-quality image without a decrease in contrast and uneven brightness. be able to.

  In addition, it is also possible to produce a prism sheet by providing a prism layer on the easy adhesion layer 24 instead of the light diffusion layer. The method for producing the prism sheet is not particularly limited, but, for example, the concave-convex mold is closely attached to the application surface of the laminated sheet 10 on which the liquid radiation-curable composition is applied on the easy-adhesion layer 24, It can be produced by a method of transferring the surface shape of the concavo-convex surface to the surface of the easy adhesion layer 24 by exposing the protective layer side to radiation such as ultraviolet rays and curing the radiation curable composition.

  Hereinafter, in order to describe the present invention in detail, experiments according to the present invention were performed as examples. However, the present invention is not limited to the embodiment shown here. Experiments 1 to 6 are examples according to the present invention, and experiments 7 to 10 are comparative examples.

(Experiment 1)
In Experiment 1, an easy-adhesion first layer is formed on one surface of a support made of polyester, an easy-adhesion second layer is formed thereon, and an easy-adhesion layer is formed. A laminated sheet was formed as a protective layer by forming a fine particle-containing layer on the surface and a surface layer thereon.

[Support]
After drying the polyethylene terephthalate (hereinafter referred to as PET) resin, polycondensed with Ge as a catalyst, to a moisture content of 50 ppm or less, the heater temperature should be approximately constant in the range of 280-300 ° C. It was melted inside the conditioned extruder. Next, this molten PET resin is discharged from a die onto an electrostatically applied chill roll to form an amorphous film, which is then stretched 3.1 times in the film transport direction, and then, The film was stretched 3.9 times in the width direction to obtain a support having a thickness of 188 μm.

[Easily adhesive first layer]
While the support was transported at a transport speed of 80 m / min, the surface was subjected to corona discharge treatment under a condition of 403 J / m ² . And the coating liquid which consists of the following composition was apply | coated to this process surface by the bar-coat method, and the easily bonding 1st layer was formed. Here, the coating amount was 7.4 cc / m ² and dried at 185 ° C. for 1 minute.

[Coating solution for easy adhesion first layer]
・ Polyester resin binder 164.23 parts by mass (manufactured by Kyoyo Chemical Industry Co., Ltd., plus coat Z687, solid content 25%)
・ Crosslinking agent 20.17 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.13 parts by mass (manufactured by NOF Corporation, Lapisol B-90, solid content 100%)
・ Surfactant 2 0.16 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

[Easily adhesive second layer]
While the support coated with the above easy-adhesive first layer was conveyed at a conveyance speed of 80 m / min, the surface of the easy-adhesion first layer was subjected to corona discharge treatment under 70.3 J / m ² . And the coating liquid which consists of the following composition was apply | coated to this process surface by the bar-coat method, and the easily bonding 2nd layer was formed, and the 0.4-micrometer-thick easily-adhesive layer was obtained. Here, the coating amount was 7.1 cc / m ² and dried at 145 ° C. for 1 minute.

[Coating solution for easy adhesion second layer]
・ Urethane resin binder 24.29 parts by mass (Mitsui Chemicals, Olester UD350, solid content 38%)
-Acrylic resin binder 3.36 parts by mass (Daicel Chemical Industries, EM-48D, solid content 27.5%)
・ Crosslinking agent 4.61 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.12 parts by mass (manufactured by NOF Corporation, Lapisol B-90, anionic, solid content 100%)
・ Surfactant 2 0.15 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (filler) 1.54 parts by mass (Nippon Aerosil Co., Ltd., Aerosil OX-50, solid content 10%)
Additive (filler) 3.80 parts by mass (Nissan Chemical Co., Ltd., Snowtex XL, solid content 40%)
・ Additive (slip agent) 1.54 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

[Fine particle containing layer]
Subsequently, while the support was transported at a transport speed of 80 m / min, a corona discharge treatment was performed on the surface of the support opposite to the surface on which the easy-adhesion layer was formed, under a condition of 403 J / m ² . Then, a coating solution having the following composition was applied by a bar coating method so that the coating amount was 8.9 cc / m ^2, and then dried at 185 ° C. for 1 minute.

[Coating liquid for fine particle-containing layer]
・ Polyester resin binder 134.03 parts by mass (manufactured by Kyoyo Chemical Industry Co., Ltd., plus coat Z687, solid content 25%)
・ Crosslinking agent 16.46 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.11 parts by mass (manufactured by NOF Corporation, Lapisol B-90, solid content 100%)
・ Surfactant 2 0.27 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Acrylic fine particles 0.92 parts by mass (manufactured by Soken Chemical Co., Ltd., MX-501, average particle size 5.4 μm, CV value 9.0)
・ Distilled water added so that the total amount becomes 1000 parts by mass

[Surface layer]
While the support coated with the fine particle-containing layer was conveyed at a conveyance speed of 80 m / min, the surface of the fine particle-containing layer was subjected to corona discharge treatment under a condition of 70.3 J / m ² . And the coating liquid which consists of the following composition was apply | coated to this process surface by the bar-coat method, the surface layer was formed, and the protective layer with a film thickness of 0.6 micrometer except a fine particle part was obtained. Here, the coating amount was 8.7 cc / m ² and dried at 145 ° C. for 1 minute to obtain a laminated sheet.

[Coating liquid for surface layer]
-Acrylic resin binder 7.82 parts by mass (Daicel Chemical Industries, EM-48D, solid content 27.5%)
・ Polyester resin binder 71.64 parts by mass (Toyobo Co., Ltd., Bironal MD-1245, solid content 30%)
・ Crosslinking agent 10.77 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.29 parts by mass (manufactured by NOF Corporation, Lapisol B-90, anionic, solid content 100%)
・ Surfactant 2 0.36 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (slip agent) 5.95 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Antistatic agent 12.41 parts by mass (manufactured by Lion Co., Ltd., Enagicol CNS, betaine, solid content 38%)
・ Additive 0.04 parts by mass (manufactured by Shin-Etsu Chemical Co., Ltd., TC-5, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

  The completed laminated sheet was measured for total light transmittance, surface resistivity and scratch resistance by the following measurements.

[Total light transmittance measurement]
Using haze meter (NDH-1001P, Nippon Denshoku Industries Co., Ltd.), the total light transmittance, which is an index of the transmittance of the finished laminated sheet, is described in the haze value of JIS-K-6714-1977 Measured based on

[Scratch resistance]
The finished laminated sheet was conditioned for 24 hours in an atmosphere of 25 ° C. and 60% RH, and the scratch strength was measured by the following method. First, the surface of the protective layer of the sample was scratched at a speed of 1 cm / sec while changing the load from 0 to 100 g with a 0.5 mmR sapphire needle. At this time, the presence or absence of scratches on the surface was examined, and the load at which scratches were first observed visually was set as the minimum load, and this value was used as an index of scratching strength. At this time, the scratch strength satisfying the product level was rated as ◯, and the case where the product level could not be satisfied was rated as x.

(Surface resistivity measurement)
The completed laminate sheet is connected to a digital electrometer R 8252 (manufactured by Advantest) and a resiliency chamber R12704A (manufactured by Advantest) as a measuring device in an atmosphere of 23 ° C and 40% RH. The surface resistivity of the protective layer was measured according to JIS K 6911.

(Experiment 2)
In Experiment 2, a laminated sheet was produced in the same manner as in Experiment 1 except that the surface layer coating solution was changed as described below. The film thickness excluding the fine particle portion of the obtained protective layer was 0.6 μm.

[Coating liquid for surface layer]
-Acrylic resin binder 7.82 parts by mass (Daicel Chemical Industries, EM-48D, solid content 27.5%)
-Urethane resin binder 56.56 parts by mass (Mitsui Chemicals, Olester UD350, solid content 38%)
・ Crosslinking agent 10.77 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.29 parts by mass (manufactured by NOF Corporation, Lapisol B-90, anionic, solid content 100%)
・ Surfactant 2 0.36 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (slip agent) 5.95 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Antistatic agent 15.51 parts by mass (manufactured by Lion Co., Ltd., Enagicol CNS, betaine, solid content 38%)
・ Additive 0.04 parts by mass (manufactured by Shin-Etsu Chemical Co., Ltd., TC-5, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

(Experiment 3)
In Experiment 3, a laminated sheet was produced in the same manner as in Experiment 1 except that the coating solution for the surface layer was changed as follows. The film thickness excluding the fine particle portion of the obtained protective layer was 0.6 μm.

[Coating liquid for surface layer]
-Acrylic resin binder 78.16 parts by mass (Daicel Chemical Industries, EM-48D, solid content 27.5%)
・ Crosslinking agent 10.77 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.29 parts by mass (manufactured by NOF Corporation, Lapisol B-90, anionic, solid content 100%)
・ Surfactant 2 0.36 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (slip agent) 5.95 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Antistatic agent 15.51 parts by mass (manufactured by Lion Co., Ltd., Enagicol CNS, betaine, solid content 38%)
・ Additive 0.04 parts by mass (manufactured by Shin-Etsu Chemical Co., Ltd., TC-5, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

(Experiment 4)
In Experiment 4, a laminated sheet was produced in the same manner as in Experiment 1 except that the surface layer coating solution was changed as described below. The film thickness excluding the fine particle portion of the protective layer obtained was 1.3 μm.

[Coating liquid for surface layer]
・ Acrylic resin binder 23.25 parts by mass (manufactured by Daicel Chemical Industries, EM-48D, solid content 27.5%)
・ Polyester resin binder 213.09 parts by mass (manufactured by Toyobo Co., Ltd., Bironal MD-1245, solid content 30%)
・ Crosslinking agent 32.03 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.85 parts by mass (Nippon Yushi Co., Ltd., Rapisol B-90, anionic, solid content 100%)
・ Surfactant 2 1.07 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (slip agent) 17.71 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Antistatic agent 46.14 parts by mass (manufactured by Lion Co., Ltd., Enagicol CNS, betaine, solid content 38%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

(Experiment 5)
In Experiment 5, a laminated sheet was produced in the same manner as in Experiment 1 except that the coating solution for the fine particle-containing layer was changed as follows. The film thickness excluding the fine particle portion of the obtained protective layer was 0.6 μm.

[Coating liquid for fine particle-containing layer]
・ Polyester resin binder 134.03 parts by mass (manufactured by Kyoyo Chemical Industry Co., Ltd., plus coat Z687, solid content 25%)
・ Crosslinking agent 16.46 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.11 parts by mass (manufactured by NOF Corporation, Lapisol B-90, solid content 100%)
・ Surfactant 2 0.27 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Polystyrene fine particle dispersion 3.59 parts by mass (manufactured by Nippon Zeon Co., Ltd., UNF1008, average particle size 1.8 μm, solid content 20%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

(Experiment 6)
In Experiment 6, a laminated sheet was produced in the same manner as in Experiment 1 except that the coating solution for the fine particle-containing layer was changed as follows. The film thickness excluding the fine particle portion of the obtained protective layer was 0.6 μm.

[Coating liquid for fine particle-containing layer]
・ Polyester resin binder 134.03 parts by mass (manufactured by Kyoyo Chemical Industry Co., Ltd., plus coat Z687, solid content 25%)
・ Crosslinking agent 16.46 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.11 parts by mass (manufactured by NOF Corporation, Lapisol B-90, solid content 100%)
・ Surfactant 2 0.27 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Acrylic fine particles 18.4 parts by mass (Made by Soken Chemical Co., Ltd., MX-501, average particle size 5.4 μm, CV value 9.0)
・ Distilled water added so that the total amount becomes 1000 parts by mass

(Experiment 7)
In Experiment 7, a laminated sheet was produced in the same manner as in Experiment 1 except that the surface layer coating solution was changed as described below. The film thickness of the protective layer obtained was 0.6 μm.

[Coating liquid for surface layer]
-Urethane resin binder 56.56 parts by mass (Mitsui Chemicals, Olester UD350, solid content 38%)
・ Crosslinking agent 10.77 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.29 parts by mass (manufactured by NOF Corporation, Lapisol B-90, anionic, solid content 100%)
・ Surfactant 2 0.36 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (slip agent) 5.96 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Antistatic agent 11.82 parts by mass (manufactured by ADEKA, Adeka Coal CC-36, cationic, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

(Experiment 8)
In Experiment 8, a laminated sheet was produced in the same manner as in Experiment 1 except that the coating solution for the surface layer was changed as follows. The film thickness excluding the fine particle portion of the obtained protective layer was 0.6 μm.

[Coating liquid for surface layer]
-Urethane resin binder 56.56 parts by mass (Mitsui Chemicals, Olester UD350, solid content 38%)
・ Crosslinking agent 10.77 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.29 parts by mass (manufactured by NOF Corporation, Lapisol B-90, anionic, solid content 100%)
・ Surfactant 2 0.36 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (slip agent) 5.96 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Antistatic agent 7.82 parts by mass (manufactured by Kao Corporation, Rheodor TWL120, nonionic, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

[Experiment 9]
In Experiment 9, a laminated sheet was produced in the same manner as in Experiment 1 except that the coating solution for the fine particle-containing layer was changed as follows. The film thickness excluding the fine particle portion of the obtained protective layer was 0.6 μm.

[Coating liquid for fine particle-containing layer]
・ Polyester resin binder 134.03 parts by mass (manufactured by Kyoyo Chemical Industry Co., Ltd., plus coat Z687, solid content 25%)
・ Crosslinking agent 16.46 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.11 parts by mass (manufactured by NOF Corporation, Lapisol B-90, solid content 100%)
・ Surfactant 2 0.27 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

(Experiment 10)
In Experiment 10, a laminated sheet was produced in the same manner as in Experiment 1 except that the coating liquid for the fine particle-containing layer and the surface layer was changed as follows. The film thickness excluding the fine particle portion of the obtained protective layer was 0.6 μm.

[Coating liquid for fine particle-containing layer]
・ Polyester resin binder 134.03 parts by mass (manufactured by Kyoyo Chemical Industry Co., Ltd., plus coat Z687, solid content 25%)
・ Crosslinking agent 16.46 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.11 parts by mass (manufactured by NOF Corporation, Lapisol B-90, solid content 100%)
・ Surfactant 2 0.27 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

[Coating liquid for surface layer]
・ Urethane resin binder 24.29 parts by mass (Mitsui Chemicals, Olester UD350, solid content 38%)
-Acrylic resin binder 3.36 parts by mass (Daicel Chemical Industries, EM-48D, solid content 27.5%)
・ Crosslinking agent 4.61 parts by mass (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%)
・ Surfactant 1 0.12 parts by mass (manufactured by NOF Corporation, Lapisol B-90, anionic, solid content 100%)
・ Surfactant 2 0.15 parts by mass (manufactured by Sanyo Chemical Industries, NAROACTY CL-95, nonionic, solid content 100%)
・ Additive (slip agent) 1.54 parts by mass (manufactured by Chukyo Yushi Co., Ltd., cellosol 524, solid content 30%)
・ Distilled water added so that the total amount becomes 1000 parts by mass

Table 1 summarizes the main production conditions of each experiment and the above evaluation results.

The symbols in Table 1 are as follows.
A-1: Byronal MD-1245 (Toyobo Co., Ltd., polyester resin)
A-2: Olester UD350 (Mitsui Chemicals, urethane resin)
A-3: EM-48D (manufactured by Daicel Chemical Industries, Ltd., acrylic resin)
B-1: Energic CNS (Lion Corporation, betaine)
B-2: Adeka Coal CC-36 (manufactured by ADEKA Co., Ltd., cationic)
B-3: Rheodor TWL120 (Kao Corporation, nonionic)
C-1: MX-501 (manufactured by Soken Chemical Co., Ltd., crosslinked PMMA fine particles)
C-2: UNF1008 (made by Nippon Zeon Co., Ltd., polystyrene fine particles)

  From the above results, the laminated sheets obtained by Experiments 1 to 10 all had high transmittance. In addition, when the surface resistivity, which is an index of the ease of adhesion of foreign matters due to dust, was measured, it was excellent in Experiments 1 to 6 and Experiment 9 using a betaine-based antistatic agent having an imidazolinium skeleton. However, in Experiments 7, 8, and 10, sufficient antistatic properties were not observed. Furthermore, when the minimum load, which is an index of the scratch strength, was measured, in Experiments 1 to 8, the scratch load was high from the magnitude of the minimum load. On the other hand, in Experiments 9 to 10, the minimum was The load became very small and the scratch strength was low.

  A diffusion sheet as shown in FIG. 3 was prepared by providing a light diffusion layer on the easy-adhesion layer of the laminated sheets of Experiments 1 to 6 in which excellent evaluation results were obtained using the following coating solution. . Then, using each diffusion sheet as a sample, the degree of light diffusion and the luminance were measured by the method described later, and the optical characteristics were evaluated.

(Light diffusion layer)
While feeding the light diffusion layer coating solution and the crosslinking agent solution having the following composition with a pump such that each flow rate was 9.98 g with respect to 100 g of the light diffusion layer coating solution, .4-N60S-523-F, manufactured by Noritake Company Limited). Three minutes after preparing this mixed solution, it was applied to the easy-adhesion layer side of the laminated sheet so that the coating amount was 64.4 cc / m ^2, and this was dried at 120 ° C. for 2 minutes. A diffusion layer was formed.

[Coating liquid for light diffusion layer]
・ Methyl ethyl ketone 1.130 g
・ Acrylic resin 501.6 g
(Acridic A811BE, manufactured by Dainippon Ink & Chemicals, Inc., 50% by mass solution (hydroxyl value 17, acid value 3))
・ Julimar MB-20X 421.3 g
(Polymethylmethacrylate cross-linked organic fine particles, manufactured by Nippon Pure Chemical Co., Ltd., spherical fine particles with an average particle size of 18 μm)
・ F780F 0.97 g
(Dainippon Ink & Chemicals, Inc., 30% by weight methyl ethyl ketone solution)

[Crosslinking agent solution]
・ Methyl ethyl ketone 1039 g
・ Isocyanate compound 352 g
(Takenate D110N, manufactured by Mitsui Takeda Chemical Co., Ltd.)

(Measurement of light diffusivity)
The haze value (%) in the C light source was measured with a haze meter (manufactured by Suga Test Instruments Co., Ltd.). In addition, it means that it is excellent in light diffusibility, so that this value is large.

[Evaluation of rate of increase in front brightness]
The LCD direct backlight unit shown in Fig. 4 is used as the light source, and the above diffusion sheet is placed on the diffuser plate of the backlight unit, and the luminance meter (BM-7, manufactured by Topcon) is used. The front brightness (K ₁ ) was measured. Similarly, the front luminance (K ₀ ) without the laminated sheet was measured, and K ₁ / K ₀ was determined as the front luminance increase rate. A cold cathode tube was used as the lamp 35 in FIG.

  As a result of the above measurements, first, the hazes of the diffusion sheets obtained from the laminated sheets of Experiments 1 to 6 were 89.4%, 89.3%, 89.5%, 89.1%, 89.0%, and 95.8%, respectively, which are all excellent. Showed light diffusivity. Further, the front luminance increase rates were 1.32, 1.32, 1.32, 1.32, 1.31, and 1.41, respectively, all of which were capable of providing high image quality. From the above results, when an optical functional layer such as a diffusion layer is formed on the surface of the support opposite to the surface on which the protective layer containing the predetermined component is formed, the transparency is high and the scratch resistance is high. It was confirmed that an optical sheet excellent in the above can be obtained.

[Prism layer]
A prism sheet as shown in FIG. 5 is produced by providing the prism layer F using the following resin liquid on the easy-adhesion layer of the laminated sheet W of Experiments 1 to 6 in which excellent evaluation results were obtained. did. Then, using each prism sheet as a sample, front luminance was measured by a method described later, and optical characteristics were evaluated.

[Adjustment of resin solution]
The compounds shown below were mixed at the stated weight ratio, heated to 50 ° C. and dissolved with stirring to obtain a resin solution.

[Resin liquid]
・ BrBPA 35.0 parts by mass (epoxy acrylate containing tetrabromobisphenol A skeleton)
・ BPE200 35.0 parts by mass (NK ester BPE-200, manufactured by Shin-Nakamura Chemical Co., Ltd., ethylene oxide-added bisphenol A methacrylate, (viscosity: 590 mPa · s / 25 ° C))
・ BR-31 30.0 parts by mass (New Frontier BR-31, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., tribromophenoxyethyl acrylate, (solid at normal temperature, melting point 50 ° C. or higher))
・ LR8893X 2.0 parts by mass (Lucirin LR8893X, photo radical generator manufactured by BASF Corporation, ethyl-2,4,6-trimethylbenzoylethoxyphenyl osphine oxide)
・ MEK 43.7 parts by mass

[Production of prism sheet]
As shown in FIG. 7, a prism sheet (see FIG. 5) was manufactured by the prism sheet manufacturing apparatus 40 using the laminated sheet W of the present invention. The laminated sheet was prepared in Experiments 1 to 6 having a width of 500 mm and a thickness of 188 μm.

  The prism sheet manufacturing apparatus 40 includes a sheet supply device 41, a coating device 42, a resin curing device 45, a protective film supply device 47, a sheet winding device 48, and a drying device 49. The sheet feeder 41 sends the laminated sheet W of the present invention to the coating device. The coating device 42 includes a die coater having an exclusion type coating head 42C. Radiation curable resin 42A is sent to coating head 42C by pump 42B. The drying device 49 is a hot air circulation method, and dries the coating film with hot air set to 100 ° C., for example.

  The above [resin liquid] was used as the radiation curable resin 42A. The wet amount of the resin liquid was controlled by the pump 42B so that the amount of the radiation curable resin 42A supplied to the coating head 42C was 20 μm after the organic solvent was dried.

  The resin curing device 45 includes an embossing roller (prism forming roller) 43, a nip roller 44, a peeling roller 46, and a UV irradiation device 50. The resin curing device 45 presses the laminated sheet W on which the coating film is formed by the embossing roller 43 and the nip roller 44 on the surface of which the reflection pattern of the unevenness pattern of the prism forming portion is formed, and the unevenness pattern of the embossing roller 43 is formed. Transfer to the coated surface.

  In a state where the laminated sheet W is wound around the embossing roller 43, the UV irradiation device 50 irradiates the application surface with ultraviolet rays 45, and the uneven pattern formed on the application surface is cured. The laminated sheet W on which the concavo-convex pattern has been cured is peeled off from the embossing roller 43 by the peeling roller 46 and wound around the core by the sheet winding device 48 as a prism sheet (see FIG. 5). At this time, the protective film H is sent from the protective film supply device 47 and wound together with the prism sheet.

  As the embossing roller 43, a roller made of S45C having a length (width direction of the sheet W) of 700 mm and a diameter of 300 mm and having a surface material of nickel was used. Grooves with a pitch of 50 μm in the axial direction of the roller were formed by cutting using a diamond tool (single point) on the entire circumference of the roller surface with a width of about 500 mm. The cross-sectional shape of the groove is a triangular shape with an apex angle of 90 degrees, and the bottom of the groove has a triangular shape of 90 degrees with no flat portion. That is, the groove width is 50 μm and the groove depth is about 25 μm. Since this groove is endless without a seam in the circumferential direction of the roller, the embossing roller 43 can form a lenticular lens (prism sheet (see FIG. 5)) having a triangular cross section on the sheet W. The surface of the roller was plated with nickel after the grooves were processed. A schematic sectional view of the embossing roller 43 is shown in FIG.

  As the nip roller 44, a roller having a diameter of 200 mm and a silicon rubber layer having a rubber hardness of 90 formed on the surface thereof was used. The nip pressure (effective nip pressure) for pressing the sheet W by the embossing roller 43 and the nip roller 44 was 0.5 Pa.

As the UV irradiation device 50, a metal halide lamp was used, and the ultraviolet ray 45 was irradiated with an energy of 1000 mJ / cm ² .

[Evaluation of rate of increase in front brightness]
The LCD direct backlight unit shown in Fig. 4 is used as the light source, and the prism sheet is placed on the diffuser plate of the backlight unit, and the front is measured by a luminance meter (BM-7, manufactured by Topcon). Luminance (K ₁ ) was measured. Similarly, the front luminance (K ₀ ) without the laminated sheet was measured, and K ₁ / K ₀ was determined as the front luminance increase rate. A cold cathode tube was used as the lamp 35 in FIG.

  As a result of the above measurements, the rate of increase in front luminance was 1.45, 1.44, 1.45, 1.44, 1.44, 1.35 in order, all of which were capable of providing high image quality. From the above results, when an optical functional layer such as a diffusion layer is formed on the surface of the support opposite to the surface on which the protective layer containing the predetermined component is formed, the transparency is high and the scratch resistance is high. It was confirmed that an optical sheet excellent in the above can be obtained.

It is general | schematic sectional drawing which shows an example of the lamination sheet which concerns on this invention. It is general | schematic sectional drawing which shows an example of the lamination sheet which made the easily bonding layer and the protective layer 2 layer structure. It is general | schematic sectional drawing which shows an example of the diffusion sheet which has a light-diffusion layer. It is a schematic perspective view which shows the backlight unit which uses a diffusion sheet as a structural member. It is a schematic sectional drawing which shows an example of a prism sheet. It is a conceptual diagram which shows the outline | summary of an embossing roller. It is a conceptual diagram which shows the structure of the manufacturing apparatus of a prism sheet.

Explanation of symbols

10, 17: Laminated sheet
11, 21: Support
12, 24: Easy adhesion layer
13, 16, 23: Protective layer
14: Fine particle-containing layer
15: Surface layer
18: Easy adhesion first layer
19: Easy adhesion second layer
20: Diffusion sheet
30: Backlight unit
40: Prism sheet manufacturing equipment
41: Sheet feeder
42: Coating device
43: Embossed roller
44: Nip roller
45: Resin curing device
46: Peeling roller
47: Protection film supply device
48: Sheet winding device
49: Drying equipment
H: Protective film
W: Sheet

Claims (6)

  A support made of a biaxially stretched polyester, an easy-adhesion layer disposed on one surface of the support, a binder disposed on the other surface of the support and being a water-soluble or water-dispersible polymer, An optical laminated sheet comprising organic fine particles and a protective layer containing a betaine antistatic agent having an imidazolium skeleton.   2. The optical laminated sheet according to claim 1, wherein the organic fine particles comprise at least one of polystyrene and polymethyl methacrylate.   The optical laminated sheet according to claim 1 or 2, wherein the organic fine particles have an average particle size of 0.05 µm or more and 20.0 µm or less.   The optical laminated sheet according to any one of claims 1 to 3, wherein the binder, which is a water-soluble or water-dispersible polymer, comprises at least one of a polyester resin, a polyurethane resin, and an acrylic resin.   The protective layer is a water-soluble or water-dispersible polymer binder containing fine particles and organic fine particles, and the water-soluble or water-dispersible polymer binder and imidazolinium skeleton on the fine particle-containing layer. The optical laminated sheet according to any one of claims 1 to 4, wherein the laminated sheet is a two-layer laminate comprising a surface layer containing a conductive antistatic agent.   An image display device comprising: an optical functional member having an optical functional layer provided on the easy-adhesion layer of the optical laminated sheet according to claim 1.

Images