JP5645487B2 - Light diffusion sheet, lighting device using light diffusion sheet, and display device - Google Patents

Description

The present invention relates to a light diffusion sheet for uniformly diffusing light emitted from a light source.

Specifically, it is used for an internal illumination display device (also referred to as an internal illumination display device) that displays information using light from the inside, or a light diffusion sheet that diffuses natural light. Lighting fixtures used, lighting signs such as light pillars and light walls, interior lighting display devices such as electric signboards and internal lighting signs, internal illumination display devices used in game machines and vending machines, transmission projectors, etc. The present invention relates to a light diffusing sheet used for screens, natural light diffusing panels, windows, daylighting plates, arcades, and the like.

More specifically, the light diffusion improves the appearance of the lighting device by concealing the light source as compared with the prior art, and suppresses the occurrence of appearance defects such as discoloration, cracking, and peeling of the light diffusion sheet that occurs over time. Regarding the sheet.

An illumination device such as an illumination signboard and an internal lighting sign is composed of a light source, a light diffusion sheet, and an information display unit that displays various types of information. Conventional light diffusion sheets diffuse light from a light source by forming fine irregularities on the sheet surface or by dispersing a light diffusing agent in the sheet.

Several proposals have been made regarding excellent light diffusion sheets.

For example, a light diffusion sheet in which irregularities are formed on the sheet surface has been proposed (Patent Document 1).

In addition, light diffusion sheets containing melamine beads have been proposed (Patent Documents 2 and 3).

However, in any of the light diffusion sheets, the light source is not sufficiently concealed, and the light diffusion sheet is discolored and cracked over time, so that the occurrence of poor appearance is insufficient.

Hereinafter, a conventional light diffusion sheet will be described.

A light diffusing sheet having irregularities formed on the surface of the sheet has poor formability when the sheet is peeled from the mold during transfer of the irregularity shape of the embossing roll, and may cause poor appearance due to abnormal peeling. Further, when the sheet is handled, the unevenness on the sheet surface may be caught, and the sheet surface may be damaged. In addition, when used outdoors, dirt may adhere to the surface irregularities of the sheet and the light diffusion performance may deteriorate. Furthermore, when used in a lighting device, it is insufficient to have sufficient light transparency, conceal the light source and simultaneously achieve light diffusivity.

In addition, when a conventional light diffusion sheet using melamine beads is formed together with the melamine beads and the resin, the resin deteriorates due to heat, light, moisture, and oxygen from the light source, and the light diffusion sheet is discolored or cracked. And the light diffusion performance decreases with time. In other words, the appearance defect is not sufficiently suppressed. Further, since the melamine beads are exposed on the sheet surface, the beads may be lost. In addition, when melamine beads are added to a transparent resin typified by an acrylic resin or a vinyl chloride resin, the basic melamine resin reacts with a transparent resin having an acid tendency. Light diffusion performance may be reduced.

JP 2002-221612 A Japanese Patent Laid-Open No. 2002-228807 JP 2004-99878 A

The problem to be solved by the present invention is to provide a light diffusing sheet that is sufficiently light transmissive and that conceals the light source.

Another problem to be solved by the present invention is to provide a light diffusing sheet that suppresses the deterioration of the light transmission performance of the light diffusing sheet over time and the occurrence of poor appearance and maintains the light diffusing performance.

The light diffusing sheet of the present invention is a light diffusing sheet including at least a transparent resin, a light diffusing agent that is a sphere containing a cross-linked melamine resin, and a stabilizer, and the light diffusing sheet includes the first surface and the second surface. Has a surface,
The light from the light source enters from the first surface or the second surface, diffuses uniformly from the first surface or the second surface, and exits from the other surface.

In the light diffusing sheet of the present invention, the light diffusing agent preferably contains silica.

The light diffusion sheet of the present invention preferably has irregularities formed on at least one of the first surface and the second surface.

In the light diffusing sheet of the present invention, it is preferable that the light diffusing agent is not exposed on the first surface and the second surface of the light diffusing layer.

The light diffusion sheet of the present invention preferably has a total light transmittance of 60% or more.

The light diffusion sheet of the present invention preferably has a parallel light transmittance of 2% or less.

In the light diffusion sheet of the present invention, the thickness of the light diffusion sheet is preferably 25 to 200 μm.

In the light diffusion sheet of the present invention, it is preferable that the transparent resin contains at least one of an acrylic resin, a vinyl chloride resin, and a urethane resin.

In the light diffusion sheet of the present invention, the light diffusion sheet is preferably formed by a casting method.

The light diffusion sheet of the present invention preferably has a light-transmitting pressure-sensitive adhesive layer laminated thereon.

The light diffusing sheet of the present invention is used for lighting fixtures using lighting covers, lighting signs such as light columns and light walls, interior lighting display devices such as electrical signs and interior lighting signs, game machines, and vending machines. It is preferably used for a light diffusing sheet used for a screen such as an internal illumination display device, a transmission type projector, a panel or window for diffusing natural light, a daylighting plate, an arcade or the like.

According to the present invention, there is provided a light diffusing sheet that improves the appearance of a lighting device by concealing a light source, and suppresses appearance defects such as discoloration, cracking, and peeling of the light diffusing sheet that occur over time. can do.

Sectional drawing of the light-diffusion sheet in this invention Cross-sectional view of a light diffusion sheet according to a reference example

One preferred embodiment of the light diffusion sheet of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a light diffusion sheet according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a light diffusion sheet according to a reference example.

As shown in FIG. 1, the light diffusing sheet of the present invention includes a transparent resin and a light diffusing agent that is a spherical body containing a crosslinked melamine resin, and has a first surface and a second surface. . In FIG. 1, the light emitted from the light source enters from the first surface and exits from the second surface. It is also possible for light to enter from the second surface and to exit from the first surface.

The light diffusing agent used in the present invention is a spherical body containing at least a crosslinked melamine resin. The light diffusing sheet used in the present invention is more preferable for the silicone resin (refractive index 1) because the transparent resin, which is a preferred embodiment of the present invention, tends to diffusely reflect when the refractive index ratio is larger than that of the vinyl chloride resin (refractive index 1.539). .42) and acrylic beads (refractive index of 1.49 for PMMA) are more preferably crosslinked melamine resins (refractive index of 1.65 to 1.66). Moreover, since it is a spherical body, the shape change of the light diffusing agent hardly occurs at the time of film formation and at the time of handling the light diffusion sheet after film formation. Since the light diffusing agent can maintain a spherical shape even after film formation, the light emitted from the light source is uniformly reflected and scattered when transmitted through the light diffusing sheet, and the light diffusing sheet has sufficient light diffusibility.

The range of the preferable addition amount of the light diffusing agent used for this invention is 1-40 weight part with respect to 100 weight part of said transparent resin, Preferably it is 5-30 weight part. The amount of 1 part by weight or more is preferable because sufficient light diffusion performance can be obtained, the light source is concealed, and the appearance of the lighting device is improved. The amount of 40 parts by weight or less is preferable because the light diffusion sheet expands and contracts in an appropriate range, so that the handleability is excellent and sufficient light transmission performance is obtained.

The preferable average particle diameter of the light diffusing agent used in the present invention is 1 to 6 μm. If the average particle diameter is 1 μm or more, it is preferable because light diffuses uniformly. If it exceeds 6 μm, the unevenness of the sheet surface may become large, and the light diffusibility and handling properties may be inferior.

Such a light diffusing agent is available as, for example, Nippon Shokubai Co., Ltd. trade name Eposter L15, M05, MS, M30, S12, S6, and S, and Eposter GP.

A preferred configuration of the light diffusing agent used in the present invention is to contain silica. In particular, when the outer surface of the spherical cross-linked melamine resin is coated with silica, an undesirable reaction does not occur between the light diffusing agent containing the basic melamine resin and the transparent resin having an acid tendency, It is possible to suppress a decrease in light transmittance of the light diffusing sheet due to deterioration of the transparent resin and occurrence of poor appearance. Therefore, it is preferable because the light diffusion performance of the light diffusion sheet is sustained.

Such a light diffusing agent is available, for example, under the trade name Opt Beads S500, 2000M, 3500M, 6500M, 10500M manufactured by Nissan Chemical Industries, Ltd.

The spherical body in this specification is not necessarily limited to a true spherical body. The spherical body may have some shape distortion. For example, the spherical body means that which can be visually confirmed using a microscope.

Examples of the light source in this specification include natural light typified by sunlight, in addition to an artificial light source typified by a discharge lamp, LED, organic EL, inorganic EL, and laser. Examples of the discharge lamp include incandescent bulbs, halogen lamps, fluorescent lamps, and cold cathode tubes.

The light diffusion sheet of the present invention hides the shape and contour of the light source when the light source is turned on. The light emitted from the light source passes through the light diffusing sheet and provides sufficient light to the observer. However, when the light passes through the light diffusing sheet, the light is sufficiently diffused. Observers are extremely difficult to see. In particular, when the light diffusion sheet of the present invention is used for a line light source typified by a fluorescent lamp or a cold cathode tube, or a point light source typified by an LED, the light diffusing sheet has sufficient light transmittance when the light source is turned on. And conceal the light source, showing a uniform appearance.

In this specification, the meaning of “hiding the light source” means that light emitted from the light source is transmitted through the light diffusion sheet, the observer is sufficiently provided with information by the light, and the observer passes through the light diffusion sheet. When viewing the light source, it is extremely difficult to visually recognize the shape and contour of the light source.

A preferable configuration of the light diffusion sheet of the present invention is that irregularities are formed on at least one of the first surface and the second surface. In such a case, the light diffusion performance of the light diffusion sheet can be further enhanced by the unevenness of the surface of the light diffusion sheet in addition to the light diffusion performance by the light diffusion agent.

A preferred configuration of the light diffusion sheet of the present invention is a single layer. In the case of a single-layer structure, there is no deterioration in light diffusion performance due to delamination in the light diffusion sheet or light transmission performance due to reflection of light from the light source between layers in the light diffusion sheet, which occurs in a multilayer structure. .

When the light diffusion sheet has a single layer structure, the light transmission performance and the light diffusion performance when light enters from the first surface of the light diffusion sheet and exits to the second surface are incident from the second surface. This is substantially the same as the light transmission performance and the light diffusion performance when light is emitted to the first surface. When a lighting device is installed by combining a light diffusion sheet and a light source, the surface of the light diffusion sheet facing the light source is not limited.

When the light diffusion sheet has a structure of two or more different layers, the light transmission performance and the light diffusion performance when light enters from the first surface of the light diffusion sheet and exits to the second surface are the second surface May be different from the light transmission performance and the light diffusion performance when light enters from the light source and exits from the first surface. For this reason, the surface of the light diffusion sheet that faces the light source may be restricted.

The unevenness | corrugation in this specification means that the arithmetic mean roughness of a surface is 1 micrometer or more and the average space | interval of an unevenness | corrugation is 300 micrometers or less.

Such surface irregularities can be measured using a surface roughness measuring instrument Surfcoder SE-30D (CUTOFF 0.8 μm, reference length 0.8 mm) manufactured by Kosaka Laboratory.

The preferable structure of the light diffusing sheet of the present invention is that the contained light diffusing agent is not exposed on the first surface and the second surface. In such a configuration, the light diffusing agent is missing when the light diffusing sheet is handled, the light diffusing sheet is damaged when the light diffusing sheet is supplied in a roll shape, and the light transmittance and the light diffusing property are deteriorated. Can be suppressed.

The preferable total light transmittance of the light diffusion sheet of the present invention is 60% or more, more preferably 75% or more. If the total light transmittance of the light diffusing sheet is 60% or more, the lighting device using the light diffusing sheet of the present invention sufficiently transmits the light from the light source and becomes a lighting device with a sufficient amount of light. When used, display device information can be provided.

The parallel light transmittance of the light diffusion sheet of the present invention is preferably 2% or less, more preferably 0.5% or less. If the light diffusing sheet has a parallel light transmittance of 2% or less, it has sufficient light transmission, diffuses light uniformly, and conceals the light source, so the appearance of the lighting device is excellent and the information transmission performance is improved. To do.

The preferred thickness of the light diffusion sheet of the present invention is 20 to 200 μm, more preferably 30 to 60 μm. If it is 20 micrometers or more, it has sufficient light transmittance and can conceal a light source. Moreover, if it is 200 micrometers or less, the workability | operativity at the time of handling a light-diffusion sheet will improve.

The transparent resin that can be used in the present invention can use a resin having a large refractive index ratio with the crosslinked melamine resin, such as acrylic resin, halogen-containing resin, polystyrene, polyester, polycarbonate, polyolefin, polyalicyclic olefin, A urethane resin and a cellulose ester resin. The acrylic resin composition contains various (meth) acrylic acid esters represented by methyl (meth) acrylate, (meth) acrylic acid, copolymers thereof, and alloys.

Preferred transparent resins used in the present invention are acrylic resins, vinyl chloride resins, and urethane resins.

Since the acrylic resin, the vinyl chloride resin, and the urethane resin have high light transmission performance, light transmitted through the light diffusion sheet is not lost, and the lighting device using the light diffusion sheet of the present invention transmits sufficient information.

Moreover, when an acrylic resin, a vinyl chloride resin, and a urethane resin are used, additives such as a stabilizer are difficult to bleed out. When the additive bleeds out, the stability of the light diffusion sheet to heat and light may be lost. In addition, the bleeding out of the additive is one of the causes of poor sheet appearance.

Moreover, when an acrylic resin, a vinyl chloride resin, and a urethane resin are used, the workability at the time of film formation is excellent, such as the thickness control at the time of film formation being easy. Among these, vinyl chloride resin is particularly preferable because it is inexpensive.

The refractive index ratio between the light diffusing agent and the transparent resin used in the present invention is preferably 1.01-1.13. When the refractive index ratio is 1.01 or more, light from the light source is sufficiently diffused. Moreover, if it is 1.13 or less, the light transmission performance fall can be made small, without the light from a light source light-diffusing excessively between the said light-diffusion agent and the said transparent resin.

The light diffusion sheet of the present invention contains one or more stabilizers. Since the stabilizer is included, the light transmission performance of the light diffusing sheet over time due to heat and light from the light source, moisture, and oxygen and the occurrence of poor appearance are suppressed, and the light diffusing performance is maintained.

Examples of the stabilizer used in the light diffusion sheet of the present invention include, but are not limited to, a heat stabilizer, a stabilizer, and a light stabilizer. Stabilizers are stabilizers that are used to increase the stabilizing function of other stabilizers.

As a heat stabilizer,
Tin-based stabilizers such as dialkyltin dicarboxylates, dialkyltin malate esters, and dialkyltin mercaptides;
And metals (Li, Na, etc.) of organic acids (octanoic acid, 2-ethylhexanoic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, eicosanoic acid, behenic acid, benzoic acid, etc.) , K, Cs, Cu, Be, Mg, Ca, Sr, Ba, Zn, Cd, Sn, Pb and the like). These heat stabilizers are preferably used when a vinyl chloride resin is used as the transparent resin which is a preferred embodiment of the present invention.

As a stabilizing aid,
Phosphite compounds such as triphenyl phosphite, trisnonylphenyl phosphite, and 4,4′-isopropylidene-diphenol-alkyl phosphite,
And perchloric acid metal salts such as sodium perchlorate and barium perchlorate,
2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6-tetramethyl-4-piperidyl Benzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6) -Tetramethyl-4-piperidyl) butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl- 4-piperidyl) .di (tridecyl) -1,2,3,4-butanetetracarboxylate, 3,9-bis [1,1-dimethyl-2- {tris (2 2,6,6-tetramethyl-4-piperidyloxycarbonyloxy) butylcarbonyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5.5] undecane, 3,9-bis [1,1 -Dimethyl-2- {tris (1,2,2,6,6-pentamethyl-4-piperidyloxycarbonyloxy) butylcarbonyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5.5] Undecane, bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2-butyl-2- (3,5-ditert-butyl-4-hydroxybenzyl) malonate, 1- (2-hydroxy Ethyl) -2,2,6,6-tetramethyl-4-piperidinol / diethyl succinate polycondensate, 1,6-bis (2,2,6,6-tetraethyl-4-piperidyl) Mino) hexane / dibromoethane polycondensate, 1,6-bis (2,2,6,6-tetramethyl-4-piperidylamino) hexane / 2,4-dichloro-6-morpholino-s-triazine polycondensate 1,6-bis (2,2,6,6-tetramethyl-4-piperidylamino) hexane / 2,4-dichloro-6-tert-octylamino-s-triazine polycondensate, 1,5,8 , 12-tetrakis [2,4-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -s-triazin-6-yl] -1,5,8 , 12-tetraazadodecane, 1,5,8,12-tetrakis [2,4-bis (N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino) -s -Triazin-6-yl] -1,5,8,12 -Tetraazadodecane, 1,6,11-tris [2,4-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -s-triazine-6 Ylamino] undecane and 1,6,11-tris [2,4-bis (N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino) -s-triazine-6 Hindered amine compounds such as -ylamino] undecane.

As another stabilizing aid,
Epoxy compounds such as epoxidized soybean oil, epoxidized linseed oil, bisphenol A diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether,
And β-diketone compounds such as benzoylacetone, dibenzoylmethane, and stearoylbenzoylmethane,
And inorganic stabilizers such as hydrotalcites and zeolites. These stabilizing aids are preferably used when a vinyl chloride resin is used as the transparent resin which is a preferred embodiment of the present invention.

As a light stabilizer,
Benzophenone compounds such as 2,3′-dihydroxy-4,4′-dimethoxybenzophenone, 2,2′-dihydroxy-4-methoxybenzophenone and 2,2 ′, 4,4′-tetrahydroxybenzophenone,
2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-methylphenyl) -5,6-dichlorobenzotriazole), 2- (2 '-Hydroxy-5'-t-butylphenyl), benzotriazole, 2- (2'-hydroxy-3'-methyl-5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy- 3 ', 5'-di-t-butylphenyl) -5-chloro-benzotriazole, 2- (2'-hydroxy-5'-phenylphenyl) -5-chlorobenzotriazole, 2- (2 '-Hydroxy-3', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl)- 5-chlorobenzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-t-amylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di- t- Tilphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-octylphenyl) benzotriazole, 2- {2′-hydroxy-3 ′-(3 “, 4”, 5 “, 6”- Tetrahydrophthalimidomethyl) -5′-methylphenyl} benzotriazole, 2- {2-hydroxy-3,5-bis (α, α′-dimethylbenzyl) phenyl} -2-hydroxybenzotriazole, etc. Benzotriazole compounds,
And cyanoacrylate compounds such as ethyl-2-cyano-3,3-diphenyl acrylate and 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate,
However, it is not limited to these.

A particularly preferred light stabilizer used in the light diffusion sheet of the present invention is a cyanoacrylate compound. When a cyanoacrylate compound is used, there is no initial coloring with respect to a transparent resin, and light transmittance is excellent.

Two or more kinds of light stabilizers used in the light diffusing sheet of the present invention can be used in combination, and the preferred addition amount is 0.5 parts by weight or more in total with respect to 100 parts by weight of the transparent resin and 6 weights per kind. Or less. There is no particular limitation as long as the light diffusing agent is uniformly dispersed in the resin at the time of film formation and does not affect the light diffusibility of the light diffusing sheet. The light stabilizer is lost from the light diffusing sheet due to bleeding out and decomposition of the light stabilizer due to, so that the weather resistance improvement effect may not be obtained. By adding 0.5 part by weight or more, sufficient weather discoloration resistance of the light diffusion sheet can be achieved. Particularly preferably, it is 3.0 parts by weight or more. Even when adding a light stabilizer in an amount more than that normally assumed by those skilled in the art, for example, 0.5 parts by weight or more, when the light diffusion sheet of the present invention is formed, sufficient light transmission and light diffusion performance are maintained. And the appearance is excellent. If it exceeds 6 parts by weight per type, the light diffusion sheet may bleed or bloom.

The stabilizer used in the light diffusion sheet of the present invention preferably uses a tin-based stabilizer, a phosphite compound, and a light stabilizer in combination. This is particularly preferable for improving the initial light transmittance, initial colorability, heat discoloration resistance, and weather discoloration resistance of the light diffusion sheet.

The weather discoloration resistance of the light diffusing sheet of the present invention can be evaluated with an accelerated exposure device such as a sunshine weatherometer.

As shown in FIG. 2, in the light diffusion sheet of the present invention, a light-transmitting pressure-sensitive adhesive layer can be laminated on at least one of the first surface and the second surface. In FIG. 2, the pressure-sensitive adhesive layer is laminated on the second surface side of the light diffusion sheet. In FIG. 2, the light from the light source enters the first surface and exits from the second surface, but the light diffusion sheet and the light source are arranged so that the light enters from the second surface and exits from the first surface. It is also possible to install.

The light diffusion sheet of the present invention in which the pressure-sensitive adhesive layer is laminated can be used by being attached to a light-transmitting substrate.

Examples of the light transmissive substrate include various glasses and various transparent resins.

Examples of the various glasses include various glasses represented by soda lime glass, borosilicate glass, lead glass, aluminosilicate glass, borate glass, and phosphate glass.

Examples of the various transparent resins include acrylic resins, halogen-containing resins represented by vinyl chloride, polystyrene, polyester, polycarbonate, and polyolefin.

Resins used for the light-transmitting pressure-sensitive adhesive layer are acrylic, epoxy, polyester, urethane, silicone, phenol, vinyl acetate, and rubber.

In particular, an acrylic pressure-sensitive adhesive is preferable because of its excellent light transmission, light stability, and heat stability.

The light-transmitting pressure-sensitive adhesive layer preferably contains various stabilizers. When the pressure-sensitive adhesive layer contains various stabilizers, particularly a heat stabilizer and a light stabilizer, there is no particular limitation, but the stabilizer contained in the light diffusion sheet of the present invention can be used. The stabilizer in the pressure-sensitive adhesive layer may be the same as or different from the stabilizer used in the light diffusion sheet of the present invention.

The light diffusion sheet of the present invention can be formed by an extrusion method, a calendar method, and a casting method. The casting method is preferable because it can reduce unevenness in the thickness of the light diffusion sheet and can easily control the light diffusion property and light transmission property uniformly.

For film formation of the light diffusion sheet of the present invention, a carrier sheet or a seamless metal belt can be used. As the carrier sheet, a film having a smooth surface and a film having minute irregularities can be used.

The carrier sheet used for film formation of the light diffusion sheet of the present invention is preferably a mat PET having minute irregularities formed on the surface. By using the mat PET, the unevenness of the mat PET surface can be easily and inexpensively transferred to the light diffusion sheet.

The light diffusion sheet of the present invention can be combined with an information display unit. It is possible to provide an information display unit for displaying various information composed of an arbitrary design and characters on either the first surface or the second surface of the light diffusion sheet. The information display unit can be provided by pasting or printing a colored film. There are two types of information display units: those that transmit light and those that conceal light.

The light diffusing sheet of the present invention preferably contains various colorants. Examples of such various colorants include organic pigments, inorganic pigments, and organic dyes.

The light diffusion sheet of the present invention is also preferably colored by inkjet printing, screen printing, gravure printing, offset printing, or the like. Among them, ink-jet printing is preferable because the ink thickness is thin compared to screen printing, and light transmittance is good, and an electronic image can be directly printed. Especially, solvent-type ink-jet printing is an image on the light diffusion film of the present invention. It is preferable because it is excellent in sharpness and adhesion.

Moreover, it is also preferable to laminate | stack a light transmissive colored film on a light-diffusion sheet, and it is also preferable that this light transmissive colored film is printed by the above printing methods.

Thus, in addition to the light diffusion sheet itself having a function for displaying information, it is preferable to provide an internal illumination display device by providing a layer having an information display function on the light diffusion sheet.

The light diffusion sheet of the present invention can contain various fillers. For example, light calcium carbonate, heavy calcium carbonate, aluminum dioxide, aluminum hydroxide, talc, titanium dioxide, barium sulfate, and silicon dioxide.
Silicon dioxide produced by various production methods such as a pulverization method, a pulverization melting method, a precipitation method, and a gas phase method can be used. By containing the filler, the light diffusion performance can be further enhanced.
As the titanium dioxide, a rutile crystal structure, an anatase crystal structure, and various surface treated products thereof can be used. By containing the filler, the total light transmittance of the light diffusion film can be adjusted.

The light diffusion sheet of the present invention can be colored with a colorant. The colorant is not particularly limited, but is preferably a weatherable and durable colorant that can be used for a long time. Specifically, COLOR INDEX 3RD EDITION (Seconded by THE SOCIETY OF DYERS AND COLORISTS) Revision) (1982) and SUPPLEMENT (1982).

The colorant names shown below are based on the COLOR INDEX GENERIC NAME specified in the same document. For example, Y-1 is C.I. I. PIGMENT YELLOW1 means O is orange (ORANGE), R is red (RED), V is purple (VIOLET), B is blue (BLUE), C is green (GREEN), Br is brown (BROWN), Bk Represents black (BLACk) and W represents white (WHITE).

As the color of the colorant, any color tone such as yellow, orange, red, purple, blue, green, brown, black and white can be used. Hereinafter, each preferable colorant is specifically illustrated. Examples of preferable yellow colorants include azo, condensed polycyclic, metal complex, and inorganic pigments.

Preferred examples of the azo pigment include insoluble monoazo pigments (Y-97, Y-116, Y-120, Y-151, Y-154) and disazo pigments (Y-81, Y-83, Y-155). , Condensed azo pigments (Y-93, Y-94, Y-95, Y-128), and preferable examples of condensed polycyclic pigments include anthraquinone pigments (Y-24, Y- 108, Y-147, Y-123, Y-99), isoindolinone pigments (Y-109, Y-110, Y-173), isoindoline pigments (Y-139), and quinophthalone pigments (Y-138). Examples of preferable metal complex salt pigments include azomethine pigments (Y-117, Y-129), nickel nitroso pigments (Y-153), and nickel azo pigments (G- 0) can be mentioned. Furthermore, as an inorganic type preferable pigment, iron oxide yellow- (Y-42), titanium-antimony-nickel oxide (Y-53) etc. can be mentioned, for example.

Examples of preferred orange pigments include azo pigments and condensed polycyclic pigments. Preferred examples of the azo pigment include insoluble monoazo pigments (O-36, O-5, O-38, O-60, O-62), disazo pigments (O-34), and condensed azo pigments ( In addition, examples of preferable condensed polycyclic pigments include perylene pigments (O-43), anthraquinone pigments (O-40, O-51), and isoindolinone pigments. Examples thereof include pigments (O-42) and quinacridone pigments (O-48, O-49).

Examples of preferable red pigments include azo pigments, condensed polycyclic pigments, and inorganic pigments.

Preferred examples of the azo pigment include insoluble monoazo pigments (R-2, R-6, R-7, R-9, R-10, R-12, R-14, R-112, R-146. R-147, R-170, R-171, R-175, R-185, R-187, R-188, R-208), azo lake pigments (R-52: 2, R-115, R-151, R-243), condensed azo pigments (R-144, R-166, R-214, R-220, R-221, R-242), disazo pigments (R-38, R-37) ).

Further, examples of preferable condensed polycyclic pigments include anthraquinone pigments (R-168, R-177, R-216), thioindigo pigments (R-88), perinone pigments (R-194), and perylenes. Pigments (R-123, R-149, R-178, R-179, R-190, R-224), quinacridone pigments (V-19, R-122, R-202, R-207, R- 209, R-206).

Further, as a new pigment, a diketopyrrolopyrrole pigment (Irgazine DPP Red BO manufactured by Ciba-Gaigi) can be mentioned, and preferred inorganic pigments include Bengala (red iron oxide R-101), zinc / iron oxide (R-225).

Examples of preferred purple pigments include azo pigments, condensed polycyclic pigments, and inorganic pigments.

Examples of preferred azo pigments include monoazo pigments (V-50), and examples of preferred condensed polycyclic pigments include perylene pigments (V-29) and anthraquinone pigments ( V-31, V-33), thioindigo pigments (V-38, V-36), quinacridone pigments (V-19), dioxazine pigments (V-23, V-37). Preferred inorganic pigments include, for example, cobalt phosphate (V-14: 1), ferrolite violet pigment (V-18), cobalt lithium vanadium phosphate pigment (V-47) and the like. Can be mentioned.

Examples of preferable blue pigments include phthalocyanine pigments, condensed polycyclic pigments, and inorganic pigments.

Preferable phthalocyanine pigments include, for example, α-type copper phthalocyanine pigments (B-15: 1, B-15: 2), β-type copper phthalocyanine pigments (B-15: 3, B-15: 4) ε. Type phthalocyanine pigments (B-15: 6) and metal-free phthalocyanine pigments (B-16). Preferred examples of condensed polycyclic pigments include indatron pigments (B-60, B-21, B-22, B-64).

In addition, examples of preferable inorganic pigments include amber (B-27), ultramarine blue (B-29), cobalt-aluminum oxide pigment (B-28), and cobalt-chromium-aluminum oxide pigment (B -3 etc.

Further, examples of preferable green pigments include phthalocyanine pigments, condensed polycyclic pigments, and inorganic pigments.

Preferable phthalocyanine pigments include, for example, medium chlorinated copper phthalocyanine pigment (G-37), high salt bromide copper phthalocyanine pigment (G-7), and high salt brominated copper phthalocyanine pigment (G-36). Examples of preferred condensed polycyclic pigments include violant long lean (G-47), and preferred inorganic pigments include, for example, chromium oxide pigments. (G-17), cobalt-titanium-nickel-zinc oxide pigment (G-9), cobalt-titanium pigment (G-50) and the like.

Examples of preferable brown pigments include azo pigments, condensed polycyclic pigments, and inorganic pigments.

Preferred examples of the azo pigment include monoazo pigments (Br-25, Br-32), metal complex azo pigments (Br-5, Br-2), and condensed azo pigments (Br-23). Examples of preferable condensed polycyclic pigments include anthraquinone pigments (Br-28) and perylene pigments (Br-26).

Preferred inorganic pigments include, for example, iron oxide pigments (Br-6), iron-chromium oxide pigments (BR-29), and zinc-iron oxide pigments (Br-31). . Moreover, as a black preferable pigment, there are an organic pigment and an inorganic pigment, and as an organic preferable pigment, for example, aniline black (Bk-1), perylene black (Bk-31) and the like can be mentioned. Can

Examples of inorganic preferred pigments include carbon black (Bk-31), carbon black (Bk-7), carbon black (Bk-9), iron black (Bk-11), Examples thereof include cobalt oxide pigments (Bk-13).

Moreover, as a white-type preferable pigment, an inorganic pigment is preferable, for example, zinc white (W-4), zinc sulfide (W-7), titanium dioxide (W-6), calcium carbonate (W-18). , Clay (W-19), barium sulfate (W-21), alumina white (W-24), silica (W-27), muscovite (W-20), tank (W-26), etc. Can do.

Other particularly preferred pigments include, for example, titanium dioxide-coated mica known as a par pigment, and those having a particle size of 2 to 200 μm are preferred, more preferably 4 to 150 μm, particularly Preferably it is 5-100 micrometers. Moreover, it is preferable that the titanium oxide of a coating layer is a rutile type from a point of a weather resistance.

Furthermore, it may be colored with a colorant such as iron oxide, may exhibit an interference color, or may have a silvery or milky color.

Commercially available products include those made by Merck, Iriojinmar, and highlights. In addition to the pigment, the colored resin layer can contain mica and aluminum powder as long as the transparency and weather resistance are not affected.

As a colorant, it is a preferred embodiment to use a color base that is commercially available in the form of a pigment dispersed in a resin. Polyester plasticizer color base, acrylic resin color base, vinyl acetate resin color base, cellulose resin color base, and the like can be used.

The light diffusion sheet of the present invention can be used as a lighting device in combination with a light source. Specifically, lighting fixtures using lighting covers, lighting signs such as light pillars and light walls, interior lighting display devices such as electrical signs and interior lighting signs, internal lighting displays used in gaming machines, vending machines, etc. It is preferably used for a light diffusion sheet used for a screen of an apparatus, a transmission type projector, or the like.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

Example 1
The following raw materials were stirred at 2000 rpm × 30 minutes using a TK homodisper manufactured by PRIMIX Co., Ltd. to obtain a uniform organosol.
Transparent resin: Paste vinyl chloride resin P-540 (refractive index: 1.539) manufactured by Vitec Co., Ltd.
100 parts by weight
Plasticizer: Polyester plasticizer Finesizer NS-5701 manufactured by Dainichi Seika Co., Ltd.
31 parts by weight modifier: Nippon Carbide Industries Co., Ltd. solution type acrylic resin MM075A-1 30 parts by weight Thermal stabilizer: Katsuta Kako Co., Ltd. octyl tin mercaptide TM-188J 1 part by weight Stabilizer: ADEKA ) Adeka Stub 1500
0.5 parts by weight light stabilizer: UB Japan 3039 4 parts by weight Solvent: ExxonMobil Solsorbo 100 50 parts by weight Light diffusing agent: Nippon Shokubai Co., Ltd. Epostor S12 (refractive index 1.66) ) 18 parts by weight of the obtained organosol was applied to an uneven surface on a sand-treated PET LSM100X film manufactured by Lintec Co., Ltd. with an uneven surface using an applicator with a micrometer manufactured by Tester Sangyo Co., Ltd. The solvent was volatilized in an oven 80 ° C. for 2 minutes, cured for 1 minute in a gear oven 200 ° C. manufactured by Toyo Seiki Co., Ltd., and peeled from the PET film to prepare a sheet having a thickness of 50 μm.

Example 2
A sheet was produced in the same manner as in Example 1 except that the thickness was 22 μm.

Example 3
A sheet was produced in the same manner as in Example 1 except that the thickness was 25 μm.

Example 4
A sheet was produced in the same manner as in Example 1 except that the thickness was 100 μm.

Example 5
A sheet was produced in the same manner as in Example 1 except that the thickness was 205 μm.

Example 6
A sheet was prepared in the same manner as in Example 1 except that a Tetoron film G2Z manufactured by Teijin DuPont Polyester Film Co., Ltd. having a smooth surface was used in place of the sand-treated PETLSM100X film manufactured by Lintec Co., Ltd. as a carrier sheet.

Example 7
A sheet was prepared in the same manner as in Example 1 except that OPTOBEADS 2000M (refractive index: 1.65) manufactured by NISSAN CHEMICAL INDUSTRY CO., LTD.

Example 8
A sheet was prepared in the same manner as in Example 1 except that 0.5 parts by weight of UB Japan 3039 Ubinar 3039 was used as the light stabilizer.

Example 9
Except not using ExxonMobil Co., Ltd. Solvesso 100 as a solvent, the same raw material as in Example 1 was used, and after stirring, a sheet was produced by an extrusion method. In a molten state, the resin was poured onto the uneven surface on the sand-treated PET LSM100X film manufactured by Lintec Corporation and solidified at room temperature. When the surface state of the sheet obtained in Example 9 was confirmed with an optical microscope, ten or more light diffusing agents exposed on the surface of the sheet were observed.

Comparative Example 1
A sheet was prepared in the same manner as in Example 1 without adding the light diffusing agent.

Comparative Example 2
A sheet was prepared in the same manner as in Example 1 except that 6 parts by weight of titanium oxide dispersed pigment 070-3 manufactured by Dainichi Seika Kogyo Co., Ltd. was added as a light diffusing agent.

Comparative Example 3
A sheet was prepared in the same manner as in Example 1 except that the stabilizers, octyl tin mercaptide TM-188J manufactured by Katsuta Chemical Industries, Ltd., Adeka Stub 1500 manufactured by Adeka Co., Ltd., and Ubinal 3039 manufactured by BSF Japan Co., Ltd. were not added. did.

The obtained sheet was evaluated according to the following items. The results are shown in Table 1.

(1) The total light transmittance and the parallel light transmittance sheet were measured by Nippon Denshoku Industries Co., Ltd. Haze Meter NDH2000 (D65).

(2) Light Diffusing A white LED lighting module 100V-NSPW manufactured by EP Japan Co., Ltd. was used as a light source, and a 200 mm × 300 mm film was placed 5 cm away from the light source and observed visually.
“Good” when the light source shape is sufficiently concealed by visual inspection and has sufficient light transmittance.
If the light source shape is not sufficiently concealed but has sufficient light transmission,
Covers the light source shape sufficiently, but “possible” when the light transmission is inferior,
The case where the concealment of the light source shape was insufficient and the light transmittance was inferior was determined as “impossible”.

(3) Stable acrylic ester-based pressure-sensitive adhesive PE-121 (manufactured by Nippon Carbide Industries Co., Ltd.) Crosslinking agent CK-101 (manufactured by Nippon Carbide Industries Co., Ltd.) 2.5 with respect to 100 parts by weight An adhesive solution was prepared by mixing 25 parts by weight of ethyl acetate and 25 parts by weight of ethyl acetate, coated on release paper with a paint applicator having a gap of 200 μm, heat-dried, laminated with a light diffusion sheet, and an adhesive layer was installed. The obtained light diffusion sheet with an adhesive was attached to a 1 mm thick aluminum plate to obtain a stability evaluation sheet.
Using sunshine weather meter made by Suga Test Instruments Co., Ltd., JIS K7350-4 Plastics-Exposure test method using laboratory light source-Part 4: According to the open frame carbon arc lamp, the sheet for stability evaluation has a black panel temperature of 63 ° C. The appearance of the sheet after 2000 hours of exposure with a glass filter type I was confirmed.
The case where there were cracks, cracks, or discoloration in the appearance of the sheet was determined as “impossible”.

(4) Average particle size of the light diffusing agent The particle size distribution measuring device MT3000 series manufactured by Nikkiso Co., Ltd. was used to measure the light diffusing agent using the laser diffraction scattering method. The average particle diameters of Nippon Shokubai Co., Ltd. Eposter S12 and Nissan Chemical Industry Co., Ltd. Optobead 2000M were 1.8 μm and 2.3 μm, respectively.

(5) Light diffusion sheet surface state The cross section of the light diffusion sheet was observed with an optical microscope (BX51, manufactured by Olympus Corporation) to confirm the surface state of the light diffusion sheet. When 5 points of each sample were observed, the light diffusing agent was not exposed from the surface of the light diffusing sheet in any sample except Example 9.

(6) Light diffusion performance of light diffusion sheet with pressure-sensitive adhesive layer A pressure-sensitive adhesive layer was placed on the light diffusion sheet produced in Example 1 in the same manner as (3) stability evaluation. The obtained 200 mm × 300 mm sheet with the pressure-sensitive adhesive layer was attached to a glass plate having a thickness of 2 mm that was degreased and washed with isopropanol. The white LED illumination module 100V-NSPW manufactured by AP Japan Co., Ltd. was used as a light source, and the light diffusion sheet was installed 5 cm away from the light source so that the light diffusion sheet installation surface was opposed, and observed visually.
Unevenness was not seen. Moreover, the shape and outline of the light source could not be confirmed, and the concealment performance was high. When the light diffusion sheet produced in Comparative Example 1 was evaluated in the same manner with an adhesive layer, light was not diffused, and the light source could be clearly confirmed visually, including its outline.

Used for internal illumination display devices (also called internal illumination display devices) that display information using light from the inside and light diffusion sheets that diffuse natural light. Specifically, illumination using illumination covers Appliances, lighting signs such as light pillars and light walls, interior lighting display devices such as electric signs and internal lighting signs, internal lighting display devices used in gaming machines and vending machines, screens such as transmission projectors, It is possible to provide a light diffusion sheet used for panels, windows, daylighting plates, arcades and the like that diffuse natural light.

DESCRIPTION OF SYMBOLS 1 ... Light-diffusion sheet 2 ... Light-diffusion agent 3 ... Transparent resin 4 ... Adhesive layer 11 ... First surface 12 ... Second surface 21 ... Light from a light source

Claims (13)

A light diffusing sheet comprising at least a vinyl chloride resin, a light diffusing agent that is a sphere containing a cross-linked melamine resin, and 2-ethylhexyl-2-cyano-3,3-diphenyl acrylate , Having a first surface and a second surface, light from the light source enters from the first surface or the second surface, diffuses uniformly from the first surface or the second surface, and exits from the other surface. Characteristic light diffusion sheet. The light diffusing sheet according to claim 1, wherein the light diffusing agent contains silica. 3. The light diffusing sheet according to claim 1, wherein at least one of the first surface and the second surface is uneven. 4. The light diffusing sheet according to any one of claims 1 to 3, wherein the light diffusing agent is not exposed on the first surface and the second surface of the light diffusing sheet. The light diffusion sheet according to claim 1, wherein the light diffusion sheet has a total light transmittance of 60% or more. 6. The light diffusing sheet according to claim 5, wherein the light diffusing sheet has a parallel light transmittance of 2% or less. The light diffusion sheet according to claim 1, wherein the light diffusion sheet has a thickness of 25 to 200 μm. The light diffusion sheet according to any one of claims 1 to 7 , wherein the light diffusion sheet is formed by a casting method. The light diffusion sheet according to any one of claims 1 to 8 , wherein the light diffusion sheet is colored. The light diffusing sheet according to any one of claims 1 to 9 , wherein a light-transmitting pressure-sensitive adhesive layer is laminated on at least one of the first surface and the second surface. The illuminating device using the light-diffusion sheet as described in any one of Claims 1-10 . An internal illumination type display device, wherein a light-transmitting colored film is laminated on the light diffusion sheet according to any one of claims 1 to 10 . An internal illumination display device, wherein the light diffusion sheet according to any one of claims 1 to 10 is printed by an ink jet printer.