JP2008170648A - Light diffusing plate and manufacturing method thereof - Google Patents

Abstract

An object of the present invention is to provide a light diffusing plate having excellent concealability and a good display contrast when combined with two polarizing plates, and a method for producing the same. ) And particles (B) having an average particle diameter of 1.5 to 20 μm, and a resin sheet having a content of the particles (B) of 0.1 to 10% by weight has a surface roughness of 0.3 s or less. It can be manufactured by sandwiching between a metal roll and a metal belt having a surface roughness of 0.3 s or less, and pulling the metal roll at a temperature 20 to 50 ° C. lower than the glass transition temperature of the thermoplastic resin (A). .
[Selection figure] None

Description

  The present invention relates to a light diffusing plate including a thermoplastic resin and particles having a specific average particle diameter and having a small residual retardation, and a method for producing the same.

  In general, a light diffusion plate is used for a backlight used as a light source of a liquid crystal display device in order to ensure uniformity in luminance. In particular, in the case of a so-called direct type backlight used as a light source for a large-sized liquid crystal display device in which a light diffusing plate is arranged on a plurality of cold cathode tubes, it is important to ensure luminance uniformity. A light diffusion plate using a light diffusing thermoplastic resin composition in which organic or inorganic fine particles are dispersed in a transparent thermoplastic resin has been used as a substantially essential member ( JP 2006-2024 A).

  These particles for imparting a diffusion function include inorganic particles such as glass, silicon dioxide, calcium carbonate, zirconia, and silicon resin, and organic particulate polymers that are polymerized and cross-linked with acrylic monomers and styrene monomers as the main components. ing. Furthermore, in order to improve the balance between light diffusion performance and brightness, a particulate material having a hollow is also used (Japanese Patent Laid-Open No. 2006-2024).

In addition, a diffusion state can be obtained by providing a light diffusion layer between two polarizing plates, and a technique (Japanese Patent Laid-Open No. 2006-98937) for concealing a light source using this may be used. . However, this technique has a problem that light leakage due to optical distortion occurs due to distortion of the material laminated as a light diffusion layer between the polarizing plates, but this problem has not yet been solved. .
JP 2006-2024 A JP 2006-98937 A

  The present invention is intended to solve the problems associated with the prior art as described above, and is a light diffusing plate excellent in concealment and having a good display contrast when combined with two polarizing plates, and its production It aims to provide a method.

  As a result of diligent research to solve the above problems, the present inventors have obtained a case where a light diffusion plate manufactured under specific conditions is excellent in concealment and has a small residual retardation, and is combined with two polarizing plates. The present inventors have found that the display contrast is good and have completed the present invention.

  That is, the method for producing a light diffusing plate according to the present invention includes a thermoplastic resin (A) and particles (B) having an average particle size of 1.5 to 20 μm, and the thermoplastic resin (A) and particles (B) A resin sheet having an absolute value of the difference in refractive index of 0.03 to 0.08 and a content of the particles (B) of 0.1 to 10% by weight has a surface roughness. It is sandwiched between a metal roll of 0.3 s or less and a metal belt having a surface roughness of 0.3 s or less, and the temperature of the metal roll is 20-50 ° C. lower than the glass transition temperature of the thermoplastic resin (A). It is characterized by taking over.

The take-up speed of the resin sheet is preferably 2 to 8 m / min. The resin sheet contains a thermoplastic resin (A) and particles (B) having an average particle size of 1.5 to 20 μm, and the content of the particles (B) is 0.1 to 10% by weight. The composition is the thermoplastic resin (A).
It is preferable that the sheet is obtained by melt extrusion at a temperature 100 to 130 ° C. higher than the glass transition temperature.

In the present invention, the thermoplastic resin (A) is preferably a cyclic olefin resin.
The light diffusion plate according to the present invention includes a thermoplastic resin (A) and particles (B) having an average particle diameter of 1.5 to 20 μm, and the content of the particles (B) is 0.1 to 10% by weight. The residual phase difference is 20 nm or less. In this light diffusion plate, the absolute value of the difference in refractive index between the thermoplastic resin (A) and the particles (B) is preferably in the range of 0.03 to 0.08. Furthermore, it is preferable to contain a fluorescent brightening agent.

  According to the present invention, a light diffusing plate having excellent concealability and a small residual phase difference can be obtained. Further, the optical member in which the light diffusing plate is sandwiched between two polarizing plates has a good display contrast.

  The light diffusing plate according to the present invention includes a thermoplastic resin (A) and particles (B) having an average particle diameter of 1.5 to 20 μm at a content of 0.1 to 10% by weight, and a residual retardation of 20 nm or less. It is. Moreover, the absolute value of the difference in refractive index between the thermoplastic resin (A) and the particles (B) is in the range of 0.03 to 0.08. Such a light diffusing plate can be produced by taking a resin sheet containing the thermoplastic resin (A) and the particles (B) having the above average particle diameter at the above-described content under specific conditions.

(A) Thermoplastic resin:
The thermoplastic resin (A) used in the present invention is not particularly limited as long as it is a thermoplastic resin used as an optical film. For example, acrylic resin such as polymethyl methacrylate resin (PMMA), polycarbonate resin, cyclic olefin Resin, polyarylate resin (PAR), polysulfone resin (PSF), polyethersulfone resin (PES), polyparaphenylene resin (PPP), polyarylene ether phosphine oxide resin (PEPO), polyimide resin (PPI), poly Examples include ether imide resin (PEI) and polyamide imide resin (PAI). Among these, a cyclic olefin resin excellent in balance of optical properties, heat resistance and moldability is particularly preferably used.

  The cyclic olefin resin (hereinafter also referred to as “cyclic olefin resin (A)”) is a cyclic olefin represented by the following formula (I) (hereinafter also referred to as “cyclic olefin (I)”). ) Polymers.

In formula (I), R ^{1 to} R ⁴ are each independently a hydrogen atom, a halogen atom or a monovalent organic group, and R ¹ and R ² , or R ³ and R ⁴ are integrated to form a divalent group. R ¹ or R ² and R ³ or R ⁴ may be bonded to each other to form a monocyclic structure or a polycyclic structure. m is 0 or a positive integer, and p is 0 or a positive integer.

As a more specific cyclic olefin resin (A),
(1) a ring-opening polymer of cyclic olefin (I) (hereinafter also referred to as “polymer (1)”),
(2) a ring-opening copolymer of cyclic olefin (I) and a copolymerizable monomer (hereinafter also referred to as “polymer (2)”),
(3) Hydrogenated (co) polymer of polymer (1) or polymer (2) (hereinafter also referred to as “polymer (3)”),
(4) A cyclized polymer (1) or polymer (2) by Friedel-Craft reaction and then hydrogenated (co) polymer (hereinafter also referred to as “polymer (4)”),
(5) a saturated copolymer of cyclic olefin (I) and an unsaturated double bond-containing compound (hereinafter, also referred to as “polymer (5)”),
(6) Addition type (co) polymer of cyclic olefin (I) and at least one monomer selected from vinyl cyclic hydrocarbon monomers and cyclopentadiene monomers, and hydrogenation thereof ( Co) polymer (hereinafter also referred to as “polymer (6)”),
(7) Alternating copolymer of cyclic olefin (I) and acrylate (hereinafter also referred to as “polymer (7)”)
Is mentioned. Of these, the polymer (3) is particularly preferably used in terms of excellent transparency and the like.

<Cyclic olefin (I)>
Examples of the monovalent organic group in the above formula (I) include C1-C30 hydrocarbon groups and monovalent polar groups other than hydrocarbon groups. Examples of the monovalent polar group include a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an allyloxycarbonyl group, an amino group, an amide group, and a cyano group. These polar groups are bonded via a linking group such as a methylene group. You may do it. Moreover, the hydrocarbon group etc. which couple | bonded through the coupling group which consists of divalent organic groups, such as a carbonyl group, an ether group, a silyl ether group, a thioether group, and an imino group, are also mentioned as a polar group. Of these polar groups, a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, and an allyloxycarbonyl group are preferable, and an alkoxycarbonyl group and an allyloxycarbonyl group are particularly preferable.

The cyclic olefin represented by the above formula (I) may be used alone or in combination of two or more.
Examples of the cyclic olefin represented by the formula (I) include, but are not limited to, the following compounds.

Bicyclo [2.2.1] hept-2-ene,
Tricyclo [4.3.0.1 ^2,5 ] -8-decene,
Tricyclo [4.4.0.1 ^2,5 ] -3-undecene,
Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
Pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13 ] -4-pentadecene, and the like.

5-methylbicyclo [2.2.1] hept-2-ene,
5-ethylbicyclo [2.2.1] hept-2-ene,
5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-methyl-5-methoxycarbonylbicyclo [2.2.1] hept-2-ene,
5-cyanobicyclo [2.2.1] hept-2-ene, and the like.

8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8-methyl-8-ethoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8-methyl-8-n-propoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-isopropoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8-n-butoxycarbonyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ]
-3-dodecene, etc.

5-ethylidenebicyclo [2.2.1] hept-2-ene,
8-ethylidenetetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, etc.
5-phenylbicyclo [2.2.1] hept-2-ene,
8-phenyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, etc.

5-fluorobicyclo [2.2.1] hept-2-ene,
5-fluoromethylbicyclo [2.2.1] hept-2-ene,
5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-pentafluoroethylbicyclo [2.2.1] hept-2-ene, and the like.

5,5-difluorobicyclo [2.2.1] hept-2-ene,
5,6-difluorobicyclo [2.2.1] hept-2-ene,
5,5-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5-methyl-5-trifluoromethylbicyclo [2.2.1] hept-2-ene, and the like.

5,5,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,5,6-tris (fluoromethyl) bicyclo [2.2.1] hept-2-ene, and the like.

5,5,6,6-tetrafluorobicyclo [2.2.1] hept-2-ene,
5,5,6,6-tetrakis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5-difluoro-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-5-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-fluoro-5-pentafluoroethyl-6,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,6-difluoro-5-heptafluoro-iso-propyl-6-trifluoromethylbicyclo [2.2.1] hept-2-ene,
5-chloro-5,6,6-trifluorobicyclo [2.2.1] hept-2-ene,
5,6-dichloro-5,6-bis (trifluoromethyl) bicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-trifluoromethoxybicyclo [2.2.1] hept-2-ene,
5,5,6-trifluoro-6-heptafluoropropoxybicyclo [2.2.1] hept-2-ene, and the like.

8-fluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-difluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-pentafluoroethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, etc.

8,8-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene,
8-methyl-8-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] −
3-dodecene, etc.

8,8,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-tris (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, etc.

8,8,9,9-tetrafluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-
Dodecene,
8,8,9,9-tetrakis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8-difluoro-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-trifluoromethoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,8,9-trifluoro-9-pentafluoropropoxytetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-fluoro-8-pentafluoroethyl-9,9-bis (trifluoromethyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8,9-difluoro-8-heptafluoroiso-propyl-9-trifluoromethyltetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-chloro-8,9,9-trifluorotetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ]
-3-dodecene,
8,9-Dichloro-8,9-bis (trifluoromethyl) tetracyclo [4.4.0.
1 ^2,5 . 1 ^7,10 ] -3-dodecene, etc.

8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene,
8-methyl-8- (2,2,2-trifluoroethoxycarbonyl) tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, and the like.

Among such cyclic olefins, in the above formula (I), R ¹ and R ³ are each independently a hydrogen atom or a carbon number of preferably 1 to 10, more preferably 1 to 4, particularly preferably 1 or 2. A hydrocarbon group, preferably an alkyl group, particularly preferably a methyl group; R ² and R ⁴ are each independently a hydrogen atom or a monovalent organic group, and at least one of R ² and R ⁴ is A hydrogen atom or the above-mentioned monovalent polar group; m is preferably an integer of 0 to 3, p is preferably an integer of 0 to 3, more preferably m + p is 0 to 4, and particularly preferably m + p is 0 to 2. And most preferred is a cyclic olefin in which m = 1 and p = 0. Cyclic olefins with m = 1 and p = 0 are most preferable in that a cyclic olefin-based resin having a high glass transition temperature and excellent mechanical strength can be obtained.

Furthermore, the cyclic olefin in which at least one of R ² and R ⁴ is a polar group represented by the following formula (II) has high glass transition temperature, low hygroscopicity, and excellent adhesion to various materials. It is preferable at the point from which a cyclic olefin resin is obtained.

_{- (CH 2) n COOR (} II)
In the formula (II), R is preferably a hydrocarbon group having 1 to 12 carbon atoms, more preferably 1 to 4 carbon atoms, particularly preferably 1 or 2, and preferably an alkyl group. Further, n is usually 0 to 5, and a cyclic olefin having a smaller value of n is preferable because a cyclic olefin-based resin having a high glass transition temperature is obtained, and a cyclic olefin having n of 0 is easy to synthesize. Is particularly preferable.

In particular, the polar group represented by the above formula (II) is bonded to the carbon atom to which R ¹ or R ³ which is an alkyl group is bonded, so that a cyclic olefin resin having low hygroscopicity is obtained. This is preferable.

Polymer (1) and polymer (2):
The polymer (1) and the polymer (2) are obtained by ring-opening polymerization of the cyclic olefin or ring-opening copolymerization of the cyclic olefin and a copolymerizable monomer in the presence of a metathesis catalyst. Obtainable.

<Copolymerizable monomer>
Examples of the copolymerizable monomer used in the polymer (2) include cycloolefin, and a cycloolefin having 4 to 20 carbon atoms, more preferably 5 to 12 carbon atoms is desirable. More specifically, cyclobutene, cyclopentene, cycloheptene, cyclooctene, dicyclopentadiene and the like can be mentioned. These cycloolefins may be used alone or in combination of two or more.

  The use ratio of the cyclic olefin and the copolymerizable monomer is preferably 100/0 to 50/50, more preferably 100/0 to 60/40 in terms of weight ratio (cyclic olefin / copolymerizable monomer). . “Cyclic olefin / copolymerizable monomer = 100/0” means the proportion of cyclic olefin used in homopolymerization.

<Catalyst for ring-opening polymerization>
The metathesis catalyst used in the ring-opening (co) polymerization reaction is a catalyst comprising a combination of the following compound (a) and compound (b).
(A) A compound containing at least one element selected from W, Mo and Re.
(B) Deming periodic table group IA elements (for example, Li, Na, K, etc.), group IIA elements (for example, Mg, Ca, etc.), group IIB elements (for example, Zn, Cd, Hg, etc.), group IIIA A compound containing at least one element selected from an element (eg, B, Al, etc.), a group IVA element (eg, Si, Sn, Pb, etc.) and a group IVB element (eg, Ti, Zr, etc.), At least one compound selected from compounds having at least one bond between an element and carbon or at least one bond between the element and hydrogen.

The metathesis catalyst may contain an additive (c) described later in order to increase its activity.
Specific examples of the compound (a) include WCl ₆ , MoCl ₆ , ReOCl _3, etc., described in JP-A No. 1-132626, page 8, upper left column, line 6 to page 8, upper right column, line 17. Can be mentioned.

Specific examples of the compound (b) include n-C ₄ H ₉ Li, (C ₂ H ₅ ) ₃ Al, (C ₂ H ₅ ) ₂ AlCl, (C ₂ H ₅ ) _1.5 AlCl _1.5 , (C ₂ H ₅₎ AlCl _2, methylalumoxane, L
Examples include iH and the compounds described in JP-A-1-132626, page 8, upper right column, line 18 to page 8, lower right column, line 3.

  As the additive (c), alcohols, aldehydes, ketones, amines and the like can be preferably used, and further, JP-A-1-132626, page 8, lower right column, lines 16 to 9. The compounds described in the upper left column, line 17 of the page can also be used.

The ratio of the said compound (a) and a compound (b) is metal atom ratio [(a) :( b)], and is usually 1: 1-1: 50, Preferably it is 1: 2-1: 30.
The ratio of the additive (c) to the compound (a) is a molar ratio [(c) :( a)] and is usually 0.005: 1 to 15: 1, preferably 0.05: 1 to 7: 1.

  The amount of the metathesis catalyst used is such that the molar ratio of the compound (a) to the cyclic olefin [(a): cyclic olefin] is usually from 1: 500 to 1: 50,000, preferably from 1: 1,000 to 1:10. , 000.

<Solvent for polymerization reaction>
In the ring-opening (co) polymerization reaction, the solvent is used as a solvent constituting a molecular weight modifier solution described later, a solvent for a cyclic olefin and / or a metathesis catalyst. Examples of such a solvent include alkanes such as pentane, hexane, heptane, octane, nonane, decane; cycloalkanes such as cyclohexane, cycloheptane, cyclooctane, decalin, norbornane; benzene, toluene, xylene, ethylbenzene, Aromatic hydrocarbons such as cumene; halogenated alkanes such as chlorobutane, bromohexane, methylene chloride, dichloroethane, hexamethylene dibromide, chloroform, tetrachloroethylene; aryl halides such as chlorobenzene; ethyl acetate, n-butyl acetate, iso- Saturated carboxylic acid esters such as butyl, methyl propionate, and dimethoxyethane; and ethers such as dibutyl ether, tetrahydrofuran, and dimethoxyethane. That. These solvents can be used alone or in combination. Of these, aromatic hydrocarbons are preferred.

The amount of the solvent used is desirably such that the weight ratio of the solvent to the cyclic olefin (solvent: cyclic olefin) is usually 1: 1 to 10: 1, preferably 1: 1 to 5: 1.
<Molecular weight regulator>
The molecular weight of the resulting ring-opening (co) polymer can be adjusted by the polymerization temperature, the type of catalyst and the type of solvent, but can also be adjusted by allowing a molecular weight regulator to coexist in the reaction system. .

  Suitable molecular weight regulators include, for example, α-olefins such as ethylene, propene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and styrene. Of these, 1-butene and 1-hexene are particularly preferable. These molecular weight regulators can be used alone or in admixture of two or more.

The usage-amount of a molecular weight regulator is 0.005-0.6 mol normally with respect to 1 mol of cyclic olefins used for ring-opening polymerization reaction, Preferably it is 0.01-0.5 mol.
The ring-opening copolymer can be obtained by ring-opening copolymerization of a cyclic olefin and a copolymerizable monomer, and further includes conjugated diene compounds such as polybutadiene and polyisoprene, styrene-butadiene copolymer, Cyclic olefins may be subjected to ring-opening copolymerization in the presence of an unsaturated hydrocarbon polymer containing two or more carbon-carbon double bonds in the main chain such as an ethylene-nonconjugated diene copolymer or polynorbornene. .

(3) Hydrogenated (co) polymer:
The ring-opening (co) polymer can be used as it is, but the hydrogenated (co) polymer (3) obtained by further hydrogenation thereof is useful as a resin having excellent impact resistance. .

  In the hydrogenation reaction, a hydrogenation catalyst is added to an ordinary method, that is, a solution containing a ring-opening (co) polymer, and hydrogen gas at normal pressure to 300 atm, preferably 3 to 200 atm, is added thereto at 0 to 200 ° C. , Preferably, it can be carried out by acting at 20 to 180 ° C.

<Hydrogenation catalyst>
As said hydrogenation catalyst, the catalyst used for the hydrogenation reaction of a normal olefinic compound can be used. Examples of the hydrogenation catalyst include a heterogeneous catalyst and a homogeneous catalyst.

  Examples of the heterogeneous catalyst include a solid catalyst in which a noble metal catalyst material such as palladium, platinum, nickel, rhodium, and ruthenium is supported on a carrier such as carbon, silica, alumina, and titania. Homogeneous catalysts include nickel naphthenate / triethylaluminum, nickel acetylacetonate / triethylaluminum, cobalt octenoate / n-butyllithium, titanocene dichloride / diethylaluminum monochloride, rhodium acetate, chlorotris (triphenylphosphine) rhodium, dichloro Examples thereof include tris (triphenylphosphine) ruthenium, chlorohydrocarbonyltris (triphenylphosphine) ruthenium, dichlorocarbonyltris (triphenylphosphine) ruthenium, and the like. The form of these catalysts may be powder or granular.

In these hydrogenation catalysts, the weight ratio of the ring-opening (co) polymer to the hydrogenation catalyst (ring-opening (co) polymer: hydrogenation catalyst) is 1: 1 × 10 ⁻⁶ to 1: 2. It is preferable to use in proportions.

The hydrogenated (co) polymer (3) has excellent thermal stability, and its characteristics are not deteriorated even by heating during molding or use as a product.
The hydrogenation rate of the hydrogenated (co) polymer (3) is usually 50% or more, preferably 70% or more, more preferably 90% or more, particularly preferably as measured by ¹ H-NMR under the condition of 500 MHz. 98% or more, most preferably 99% or more. The higher the hydrogenation rate, the better the stability against heat and light, and it is possible to obtain a light diffusing plate having stable characteristics over a long period of time.

The hydrogenated (co) polymer (3) preferably has a gel content of 5% by weight or less, particularly preferably 1% by weight or less.
(4) Hydrogenated (co) polymer:
The hydrogenated (co) polymer (4) can be obtained by cyclizing the ring-opened (co) polymer of (1) or (2) by Friedel-Craft reaction and then hydrogenating it.

  The method for cyclizing the ring-opened (co) polymer by Friedel-Craft reaction is not particularly limited, and for example, a known method using an acidic compound described in JP-A No. 50-154399 can be employed.

Specific examples of the acidic compound include AlCl ₃ , BF ₃ , FeCl ₃ , Al ₂ O ₃ , HCl
, CH ₃ ClCOOH, zeolite, Lewis acid such as activated clay, and Bronsted acid.

The cyclized ring-opening (co) polymer can be hydrogenated in the same manner as the hydrogenation reaction of the ring-opening (co) polymer.
(5) Saturated copolymer:
The saturated copolymer (5) can be obtained by addition polymerization of an unsaturated double bond-containing compound to the cyclic olefin in the presence of an addition polymerization catalyst. A conventionally known method can be applied to the addition polymerization method.

<Unsaturated double bond-containing compound>
Examples of the unsaturated double bond-containing compound include olefinic compounds such as ethylene, propylene, and butene. Among these, olefinic compounds having preferably 2 to 12 carbon atoms, more preferably 2 to 8 carbon atoms. Compounds are desirable.

  The use amount of the unsaturated double bond-containing compound is preferably 90/10 to 40/60 in terms of the weight ratio of the cyclic olefin to the unsaturated double bond-containing compound (cyclic olefin / unsaturated double bond-containing compound). 85/15 to 50/50 is more preferable. However, the total weight of the cyclic olefin and the unsaturated double bond-containing compound is 100.

<Addition polymerization catalyst>
Examples of the addition polymerization catalyst include a combination of at least one compound selected from a titanium compound, a zirconium compound, and a vanadium compound, and an organoaluminum compound as a co-catalyst.

Examples of the titanium compound include titanium tetrachloride and titanium trichloride. Examples of the zirconium compound include bis (cyclopentadienyl) zirconium chloride and bis (cyclopentadienyl) zirconium dichloride. As the vanadium compound, the following formula VO (OR) _a X _b or V (OR) _c X _d
[Wherein R is a hydrocarbon group, X is a halogen atom, and 0 ≦ a ≦ 3, 0 ≦ b ≦ 3, 2 ≦ (a + b) ≦ 3, 0 ≦ c ≦ 4, 0 ≦ d ≦ 4, 3, ≦ (c + d) ≦ 4. ]
Or an electron-donating adduct of these compounds.

  Examples of the electron donor include alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic acids or inorganic acids, ethers, acid amides, acid anhydrides, oxygen-containing electron donors such as alkoxysilanes, ammonia, amines, Examples thereof include nitrogen-containing electron donors such as nitrile and isocyanate.

  Examples of the organoaluminum compound include compounds having at least one aluminum-carbon bond or aluminum-hydrogen bond. These organoaluminum compounds may be used alone or in combination of two or more.

  The ratio of the amount used of a compound selected from a titanium compound, a zirconium compound and a vanadium compound (the total amount when two or more are used together) and the amount of the organoaluminum compound used is the ratio of aluminum atoms to titanium atoms ( Al / Ti etc.), usually 2 or more, preferably 2 to 50, particularly preferably 3 to 20.

Examples of the solvent used in the addition polymerization reaction include the solvents exemplified in the ring-opening (co) polymerization reaction.
Moreover, the molecular weight of the saturated copolymer (5) can be usually adjusted using hydrogen.

(6) Addition type (co) polymer and hydrogenated (co) polymer thereof:
The addition type (co) polymer (6) is obtained by subjecting the cyclic olefin to addition polymerization of at least one monomer selected from a vinyl cyclic hydrocarbon monomer and a cyclopentadiene monomer. Obtainable.

<Vinyl cyclic hydrocarbon monomer>
Examples of the vinyl cyclic hydrocarbon monomer include vinylcyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene, 4-vinylcyclopentane, and 4-isopropenylcyclopentane. Vinylated 5-membered hydrocarbon monomers such as vinylcyclopentane monomers such as 4-vinylcyclohexene, 4-isopropenylcyclohexene, 1-methyl-4-isopropenylcyclohexene, 2-methyl-4- Vinylcyclohexene, vinylcyclohexene monomers such as 2-methyl-4-isopropenylcyclohexene, vinylcyclohexane monomers such as 4-vinylcyclohexane and 2-methyl-4-isopropenylcyclohexane, styrene, α-methylstyrene 2-methylstyrene Styrene monomers such as 3-methylstyrene, 4-methylstyrene, 1-vinylnaphthalene, 2-vinylnaphthalene, 4-phenylstyrene, p-methoxystyrene, d-terpene, 1-terpene, diterpene, d-limonene Terpene monomers such as 1-limonene and dipentene, vinylcycloheptene monomers such as 4-vinylcycloheptene and 4-isopropenylcycloheptene, 4-vinylcycloheptane, 4-isopropenylcyclo Examples thereof include vinylcycloheptane monomers such as heptane. Of these monomers, styrene and α-methylstyrene are preferred. Moreover, these monomers may be used individually by 1 type, or may use 2 or more types together.

<Cyclopentadiene monomer>
Examples of the cyclopentadiene monomer include cyclopentadiene, 1-methylcyclopentadiene, 2-methylcyclopentadiene, 2-ethylcyclopentadiene, 5-methylcyclopentadiene, 5,5-methylcyclopentadiene, and the like. . Of these monomers, cyclopentadiene is preferred. Moreover, these monomers may be used individually by 1 type, or may use 2 or more types together.

The above addition polymerization reaction can be carried out in the same manner as the addition polymerization reaction in the saturated copolymer (5).
The hydrogenation (co) polymer of the addition type (co) polymer (6) is obtained by subjecting the addition type (co) polymer (6) to the same method as the hydrogenation (co) polymer (3). It can be obtained by hydrogenation.

(7) Alternating copolymer:
The alternating copolymer (7) can be obtained by radical polymerization of the cyclic olefin and acrylate in the presence of a Lewis acid or the like.

<Acrylate>
Examples of the acrylate include linear, branched or cyclic alkyl acrylates having 1 to 20 carbon atoms such as methyl acrylate, 2-ethylhexyl acrylate, and cyclohexyl acrylate; carbon atoms such as glycidyl acrylate and 2-tetrahydrofurfuryl acrylate. An acrylate having 2 to 20 heterocyclic groups; an acrylate having 6 to 20 carbon atoms such as benzyl acrylate; a polycyclic structure having 7 to 30 carbon atoms such as isobornyl acrylate and dicyclopentanyl acrylate The acrylate which has.

  The ratio of the cyclic olefin to the acrylate is generally 30 to 70 mol of cyclic olefin and 70 to 30 mol of acrylate, preferably 40 to 60 mol of cyclic olefin, and acrylate It is 60-40 mol, Most preferably, a cyclic olefin is 45-55 mol, and an acrylate is 55-45 mol.

As for the usage-amount of the said Lewis' acid, 0.001-1 mol is preferable with respect to 100 mol of acrylates.
In addition, known organic peroxides or azobis-based radical polymerization initiators that generate free radicals can also be used.

  The polymerization reaction temperature is usually -20 ° C to 80 ° C, preferably 5 ° C to 60 ° C. Moreover, as a solvent for polymerization reaction, the solvent illustrated in the said ring-opening (co) polymerization reaction can be mentioned.

  The “alternate copolymer” in the present invention is a copolymer in which structural units derived from cyclic olefins are not adjacent to each other, that is, a structural unit derived from acrylate is always adjacent to a structural unit derived from cyclic olefin. It means a copolymer that is bonded. However, the acrylate-derived structural units may be present adjacent to each other.

  The glass transition temperature (Tg) of the cyclic olefin resin (A) is usually 130 ° C. or higher, preferably 130 to 350 ° C., more preferably 130 to 250 ° C., and particularly preferably 140 to 200 ° C. Resins with a Tg in the above range are not easily deformed even when used under high temperature conditions or during secondary processing involving heating such as coating and printing, and are excellent in molding processability, and the resin deteriorates due to heat during the molding process. Is less likely to occur.

(B) Particles:
The particle (B) used in the present invention may be composed of one component as long as the particle surface is composed of an inorganic or organic polymer component, for example, a composite particle composed of two or more components such as core-shell type particles. But it ’s okay. The outer shape of the particles is not particularly limited, but spherical particles having substantially no corners on the surface are preferable in that the balance between light diffusibility and brightness of the obtained light diffusion plate is excellent.

The average particle diameter of the particles (B) is 1.5 to 20 μm, preferably 5 to 18 μm, and particularly preferably 10 to 15 μm. When particles having an average particle diameter in the above range are used, a sufficient diffusion effect can be obtained. On the other hand, when the average particle size is less than 1.5 μm, the diffusion effect is not sufficiently exhibited and an image cannot be formed on the sheet. On the other hand, if the average particle diameter exceeds 20 μm, a sheet having a smooth surface cannot be obtained visually, and the reflected light increases too much, so that the diffused light cannot be used efficiently. In the present invention, the average particle diameter of the particles means an average value of particle diameters measured using a light blocking particle counter.

The refractive index n _D of the particles (B) is preferably 1.44 to 1.54, and preferably 1.45 to 1.52.
Is more preferable. When particles having a refractive index in the above range are used, a light diffusing effect is exhibited, but when particles not in this range are used, an image is not formed when the addition amount is small, and the amount of light is increased when the addition amount is large. As a result, a bright image cannot be obtained. The absolute value of the difference in refractive index between the thermoplastic resin (A) and the particles (B) is in the range of 0.03 to 0.08. It is preferable to select the thermoplastic resin (A) and the particles (B) having an absolute value of the difference in refractive index within the above range because light can be used to such an extent that an image can be formed on the diffusion plate by the diffused light.

As the particles (B), known inorganic particles and / or organic particles can be used as long as the particles have the above characteristics. Examples of inorganic particles include glass, SiO ₂ ,
Examples thereof include inorganic particles such as CaCO ₃ and polyorganosiloxane compounds. Examples of the organic particles include acrylic or styrene organic crosslinked particles. Of these particles, organic cross-linked particles are preferable in view of affinity with the thermoplastic resin (A) and molding processability. This organic crosslinked particle can be obtained by polymerizing a crosslinking monomer and another polymerizable monomer as follows.

  Examples of the crosslinking monomer include non-conjugated divinyl compounds such as divinylbenzene; polyvalent acrylate compounds such as trimethylolpropane trimethacrylate and trimethylolpropane triacrylate, and two or more, preferably two copolymerizable double bonds A compound having is preferred.

  Examples of the polyvalent acrylate compound include polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-hexane glycol diacrylate, 1,6-hexane glycol diacrylate, neopentyl glycol diacrylate, and polypropylene glycol diacrylate. , 2,2-bis (4-acryloxypropyloxyphenyl) propane, diacrylate compounds such as 2,2-bis (4-acryloxydiethoxyphenyl) propane; trimethylolpropane triacrylate, trimethylolethane triacrylate, Triacrylate compounds such as tetramethylol methane triacrylate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethyleneglycol Dimethacrylate, polyethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, neopentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol di Dimethacrylate compounds such as methacrylate and 2,2-bis (4-methacryloxydiethoxyphenyl) propane; and trimethacrylate compounds such as trimethylolpropane trimethacrylate and trimethylolethane trimethacrylate.

  Of the crosslinkable monomers, divinylbenzene, ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate are preferred, and divinylbenzene is particularly preferred. Moreover, the said crosslinkable monomer can be used individually or in mixture of 2 or more types.

Other polymerizable monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, fluorostyrene and vinylpyridine; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; butyl (meth) acrylate, 2-ethylhexyl (meta ) (Meth) acrylates such as acrylate, methyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate; unsaturated fatty acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid; acrylamide, methacrylic Examples thereof include amide monomers such as amides.

  When the resin sheet is molded at a temperature at which the thermoplastic resin is heated and melted, such as injection molding or extrusion molding, it is desirable that the organic particles do not melt at the heating and melting temperature of the thermoplastic resin. Moreover, when preparing the said resin sheet using an organic solvent, it is preferable that the said organic particle does not melt | dissolve in an organic solvent.

[Resin sheet]
The resin sheet can be produced by molding a light diffusing resin composition containing the thermoplastic resin (A) and the particles (B) into a sheet shape.

<Light diffusing resin composition>
The light diffusing resin composition contains the thermoplastic resin (A) and the particles (B), and the content of the particles (B) is 0.1 to 10% by weight with respect to 100% by weight of the total. Preferably, it is 0.3 to 3% by weight. When the particles (B) are blended in the above range, it is possible to obtain a diffusion plate that does not reduce the amount of light while forming an image.

Moreover, you may mix | blend a fluorescent whitening agent with the said light diffusable resin composition in the range which does not impair the effect of this invention, for example in order to improve the hue of a resin sheet.
The method for preparing the light diffusing resin composition, that is, the method for blending the thermoplastic resin (A) and the particles (B) is not particularly limited, and can be blended by a known method. For example, (1) a method of dispersing the particles (B) in a state where the thermoplastic resin (A) is dissolved in a soluble solvent, and removing the solvent by a known method to obtain the resin composition (2) thermoplasticity Examples thereof include a method of dispersing the particles (B) in a state where the resin (A) is melted.

  In the preparation method of (1) above, as a solution containing the thermoplastic resin (A), a solution after polymerization, a solution after hydrogenation, a solution after removal of the catalyst, a concentrated solution, a pellet-shaped thermoplastic resin (A ) Can be used.

  The blending method is not particularly limited. For example, a method of mixing using a known stirrer, or a solution containing the thermoplastic resin (A) and the particles (B) are simultaneously supplied to a known extruder, and at the same time A method of performing solvent removal and dispersion may be mentioned.

  On the other hand, examples of the preparation method (2) include a method using a known single-screw or twin-screw extruder. The cylinder diameter of the extruder is usually 10 to 100 mm. A known screw can be used. For example, in the case of a single shaft, a full flight, a combination of subflights, a dull image incorporated, or a screw whose pitch or groove depth changes in the same screw. It is done. In the case of two shafts, two or three screws, screws rotating in different directions or in the same direction, and screws that can be freely combined with screw parts, the shape of the screw parts is screw, reverse feed screw, paddle type screw, It is possible to freely select from a helical paddle type screw or the like.

Only one extruder may be used, but a combination of two or more extruders or a combination of continuous and batch kneaders may be used. The raw material may be supplied to the extruder by a plurality of feeders. Moreover, you may supply particle | grains (B) from the middle of an extruder.

  Further, after the thermoplastic resin (A) and the particles (B) are mixed in a solid state in advance using a known blender such as a tumbler type or a rotary type, a Henschel mixer, a planetary mixer or the like, The particles (B) may be dispersed in the thermoplastic resin (A) by supplying to an extruder.

  It is preferable to dry the thermoplastic resin (A) or both the thermoplastic resin (A) and the particles (B) in advance by a known method. Examples of the drying method include hot air drying, dehumidifying drying, vacuum drying, and nitrogen drying. The drying temperature and drying time are not particularly limited, but can usually be arbitrarily set within the range of (Tg-100 ° C.) to (Tg-20 ° C.). Set in the range of 6 hours.

It is also preferable to seal (enclose) the hopper, charging port, vent port, die surface, and the like of the extruder with an inert gas such as nitrogen or argon.
The light diffusing resin composition is preferably as small as possible with a foreign substance having a size that can be visually discerned when a light diffusing plate is molded, preferably 50 μm or more. The content of such foreign matters is 5 pieces / 10 g or less, preferably 3 pieces / 10 g or less, and more preferably 0 pieces / 10 g.

  The content of the foreign matter can be measured by dissolving the resin composition in a solvent having resin solubility such as toluene and cyclohexane, filtering with a filter, observing with a microscope, and counting the size and number. Alternatively, the thermoplastic resin may be dissolved in the above solvent, filtered through a filter, and then counted using a commercially available fine particle counter based on the principle of light scattering.

  Moreover, it is preferable to remove the water | moisture content and oxygen component which the said light diffusable resin composition melt | dissolves by a well-known method previously, before using for the shaping | molding process mentioned later. Even when the light diffusing resin composition is in a solid form such as particles or pellets, it can be dried by a known method. As the drying device, a known drying device such as a hot air dryer, a dehumidifying dryer, a nitrogen circulation dryer, a dehumidification nitrogen circulation dryer, or a vacuum dryer can be used. Among these dryers, it is preferable to use a vacuum dryer or a dryer that circulates an inert gas such as nitrogen because a molded product having hue uniformity can be easily obtained.

  The drying temperature and the drying time are not particularly limited, but can usually be arbitrarily set in the range of Tg-100 ° C to Tg-20 ° C, and the drying time is usually in the range of 2 to 6 hours. Set with.

<Resin sheet>
The resin sheet used for this invention is obtained by shape | molding the said light diffusable resin composition in a sheet form. The resin sheet contains the thermoplastic resin (A) and the particles (B), and the content of the particles (B) is 0.1 to 10% by weight, preferably 100% by weight of the total. 0.3 to 3% by weight. A known method can be adopted as a method for forming the sheet, but it is preferable to form by a melt extrusion method from the viewpoint of simplifying the equipment and suppressing the equipment cost.

  As a method of melt-extruding the resin sheet, the light diffusing resin composition is melted with a normal extruder, quantitatively measured with a gear pump, extruded through a die having a slit-like outlet, The method of extending to a film form is mentioned.

  The melting temperature of the light diffusing resin composition is preferably 100 to 150 ° C higher than the glass transition temperature of the thermoplastic resin (A), more preferably 100 to 140 ° C higher. When the difference between the glass transition temperature of the thermoplastic resin (A) and the melting temperature of the light diffusing resin composition is within the above range, disadvantages such as resin burning at the processing temperature are unlikely to occur. It becomes possible to suppress defects generated on the surface.

  As a preferred extruder used for extrusion molding, the ratio (L / D) of length (L) to diameter (D) is 28 or more and 40 or less, and the screw diameter is determined by the amount of extrusion, but usually 30 mm to A 125 mm extruder may be mentioned. When L / D is in the above range, a suitable residence time can be obtained, and the resin composition of the present invention can be sufficiently melted. Moreover, when the screw diameter is less than 30 mm, the measurement is not stable, and the productivity may be lowered, which is not preferable. Moreover, since it will become easy to retain a raw material after measurement when it exceeds 125 mm, it is not preferable.

  It is also preferable to use a gear pump in order to achieve film thickness stability of the sheet or the like. A well-known gear pump can be used as the gear pump, but an external lubrication system that discharges the resin used for lubrication is particularly preferably used.

  As the die for stretching the resin composition of the present invention into a film shape, a T die is preferably used, and examples thereof include a coat hanger die and a fish tail die, and a coat hanger die is particularly preferable. The shape of the manifold is not particularly limited, but a manifold with a small retention is preferable. Further, the tip of the T die is preferably a sharp edge, and if there is a defect in the edge, it may cause a die line, which is not preferable. In particular, edge treatment in which a carbide coating such as tungsten-carbide is applied by a technique such as thermal spraying is convenient for preventing die lines.

(Light diffusion plate)
The light diffusing plate according to the present invention can be manufactured by sandwiching the resin sheet between a metal roll having a surface roughness of 0.3 s or less and a metal belt having a surface roughness of 0.3 s or less. At this time, the temperature of the metal roll is set to a temperature lower by 20 to 50 ° C., preferably 25 to 45 ° C. than the glass transition temperature Tg of the thermoplastic resin (A). When the temperature of the metal roll is set in the above range, the sheet is less likely to be warped or the like, and it is difficult to create a cause of distortion that causes a residual phase difference. The take-up speed of the resin sheet is preferably 2 to 8 m / min, and more preferably 2 to 6 m / min. Most preferably, it is 2.5-5 m / min. When the take-up speed is in the above range, a sheet having a good surface appearance can be obtained without deteriorating the thickness balance of the sheet.

  The metal roll and metal belt are preferably made of iron, stainless steel, hard chrome-plated iron, or the like. In order to improve releasability, it is also preferable to treat iron or stainless steel with a metal oxide such as aluminum oxide or chromium oxide or a hard metal such as tungsten or tungsten carbide by thermal spraying or the like.

The light diffusing plate thus produced has excellent concealability and a small residual phase difference, for example, good display contrast even when combined with a polarizing plate.
[Example]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by this Example. In the following, “parts” and “%” are “parts by weight” and “% by weight” unless otherwise specified.

(Glass transition temperature: Tg)
Using a DSC6200 manufactured by Seiko Instruments Inc., the temperature was increased at a rate of temperature increase of 20 ° C./min under a nitrogen stream.

(Average particle size)
The particle size distribution was measured by a light scattering method using a particle size distribution measuring device (Microtrack UAP150 manufactured by Nikkiso Co., Ltd.). The obtained particle size distribution was plotted on logarithmic probability paper, and the particle size at which the accumulation reached 50% was taken as the average particle size.

(Refractive index)
The particles are filtered through a 60-mesh wire mesh, and a refractive index standard solution (manufactured by Cargille) is added dropwise to the filter cake and mixed, and then observed with an optical microscope. Was the refractive index value of the particles. The measurement was performed at 25 ° C.

(Total light transmittance and haze)
The total light transmittance and haze of the light diffusing plate were measured according to ASTM D1003 using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory).

(Residual phase difference)
The residual phase difference of the light diffusing plate was measured using a micro-area birefringence meter (KOBRA-CCD manufactured by Oji Scientific Co., Ltd.) by cutting the obtained light diffusing plate into A4 size. .

(Display contrast)
A light diffusing plate is pasted on the polarizing plate A (POLAX-38S manufactured by Luceo Co., Ltd.), and the polarizing plate B (POLAX- manufactured by Luceo Co., Ltd.) is placed thereon so that the optical axis is orthogonal to the optical axis of the polarizing plate A. 38S) was laminated to produce an optical member C. On the other hand, a light diffusing plate was bonded onto the polarizing plate A, and a polarizing plate B was bonded thereon so that the optical axis was parallel to the optical axis of the polarizing plate A, thereby producing an optical member P. For the optical members C and P, the luminance was measured by the following method, and the contrast L was determined from the following formula.

L = luminance of optical member P / luminance of optical member C The optical member is placed at a position of 300 mm from a light box (Dentsu Sangyo Co., Ltd., large surface illumination, luminance: 9000 cd / m ² ), and a luminance meter (Konica Minolta Co., Ltd.) Company made LS-110
) Was used to measure the brightness of the light transmitted through the optical member.

Note that the luminance of the transmitted light of one polarizing plate is 4500 cd / m ² , the luminance of the transmitted light of the optical member obtained by bonding the polarizing plates A and B so that the optical axes are orthogonal to each other is 15 cd / m ² , and the polarized light Board A
The brightness of the transmitted light of the optical member obtained by bonding together B so that the optical axes are parallel was 4000 cd / m ² . Therefore, the contrast of only two polarizing plates was 270.

(Concealment)
4 corners of the light diffusing plate are clipped and placed in a screen shape, and an image is copied from the back of the light diffusing plate using a liquid crystal projector (Seiko Epson Corp., model number EMP-1710). The surface was visually observed from the front surface, and the concealability was evaluated according to the following criteria.

A: The outline of the light source of the projector cannot be seen.
B: The outline of the light source of the projector can be seen.

Cyclic olefin-based resin (manufactured by JSR Corporation, trade name: Arton D4531, Tg = 130 ° C., refractive index = 1.515) 97.5 parts by weight and diffusion particles (manufactured by Sekisui Plastics Co., Ltd., trade name: Techpolymer) SBX-12, refractive index n _D = 1.59, average particle size 12 μm) 2.5
Part by weight was mixed with a Henschel mixer, and further, 30 ppm of a fluorescent whitening agent (manufactured by Ciba Specialty Chemicals, trade name: UVITEX OB-ONE) was mixed to prepare a light diffusing resin composition A1.

  This resin composition A1 was dried at 90 ° C. for 2 hours using a dehumidifying dryer to remove moisture on the surface. Thereafter, the resin composition A1 was pelletized at 270 ° C. by supplying a fixed amount to a twin screw extruder (TEM-37 manufactured by Toshiba Machine Co., Ltd.) using a weight feeder.

  The resin composition A1 in the form of pellets was dried at 100 ° C. for 4 hours using a dehumidifying dryer, melted at 265 ° C., and then a single screw extruder (manufactured by GM Engineering Co., Ltd., screw outer diameter) D = 75 mm, L / D = 36) at a constant rate of 80 kg / hr, and melt extruded at 270 ° C. using a coat hanger type T die having a width of 600 mm to obtain a resin sheet A1.

  A metal in which the resin sheet A1 is adjusted to 80 ° C. using a sleeve-type take-up device having an endless metal belt (surface roughness 0.2 s) having a thickness of 0.3 mm and a metal roll (surface roughness 0.1 s). It was sandwiched between a belt and a metal roll and taken up at a speed of 2.5 m / min to produce a 1 mm-thick light diffusion plate A1.

  The results of evaluating the obtained light diffusion plate A1 are shown in Table 1.

95 parts by weight of styrene and 5 parts by weight of divinylbenzene are copolymerized to form crosslinked particles (refractive index n _D
= 1.592, average particle size 11 μm). A light diffusing plate B1 having a thickness of 1.0 mm was prepared in the same manner as in Example 1 except that the crosslinked particles were used in place of the techpolymer SBX-12.

  The results of evaluating the obtained light diffusion plate B1 are shown in Table 1.

A resin sheet A2 (thickness: 1.0 mm) was produced in the same manner as in Example 1 except that the amount of the cyclic olefin-based resin was changed to 98.7 parts by weight and the amount of the diffusion particles was changed to 1.3 parts by weight.
Using this resin sheet A2, a light diffusing plate A2 having a thickness of 0.8 mm was produced in the same manner as in Example 1 except that the take-up speed was changed to 3 m / min.

  The results of evaluating the obtained light diffusion plate A2 are shown in Table 1.

(Synthesis of cyclic olefin resin)
8-methyl-8-methoxycarbonyltetracyclo [4.4.0.1 ^2.5 . 1 ^7.10 ]-
175 parts of 3-dodecene (monomer A), 75 parts of 5-phenyl-bicyclo [2.2.1] hept-2-ene (monomer B) and 18 parts of 1-hexene (molecular weight regulator) And 750 parts of toluene were charged into a nitrogen-substituted reaction vessel, and the solution was heated to 60 ° C. Next, 0.62 parts of a toluene solution of triethylaluminum (.1.5 mol / l) as a polymerization catalyst and tungsten hexachloride modified with t-butanol and methanol (t-butanol: methanol: 3.7 parts of a toluene solution (concentration 0.05 mol / l) of tungsten = 0.35 mol: 0.3 mol: 1 mol) was added, and the system was opened by heating and stirring at 80 ° C. for 3 hours. A ring copolymer solution was obtained. The polymerization conversion rate in this polymerization reaction was 97%, and the intrinsic viscosity (η _inh ) of the obtained ring-opening copolymer measured in chloroform at 30 ° C. was 0.48 dl / g.

The autoclave was charged with 4,000 parts of the ring-opening copolymer solution thus obtained, and RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening copolymer solution at 0.48. A hydrogenation reaction was carried out by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 160 ° C.

  After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated cyclic olefin resin C1.

The cyclic olefin resin C1 thus obtained (hereinafter referred to as “resin C1”) was measured for hydrogenation rate using 500 MHz ¹ H-NMR and found to be 99.9%. When the proportion of the structural unit b derived from the monomer B was measured using 500 MHz ¹ H-NMR, it was 30.2%. Here, the proportion of the structural unit b is such that the absorption of the methyl proton of the methyl ester of the structural unit a derived from the monomer A appearing around 3.7 ppm and the proton of the structural unit B aromatic ring structure appearing at 7 ppm. It was calculated from the absorption.

The Tg of Resin C1 was 130 ° C. Moreover, when the number average molecular weight (Mn) and weight average molecular weight (Mw) of polystyrene conversion were measured by GPC method (solvent: tetrahydrofuran), Mn was 16,000, Mw was 58,000, and molecular weight distribution (Mw / Mn). ) Was 3.62 and the intrinsic viscosity (η _inh ) was 0.50 dl / g. Furthermore, when the saturated water absorption rate at 23 ° C. was measured, it was 0.15%. The refractive index of this resin was 1.531.

(Preparation of diffusion particles)
250 parts by weight of ion-exchanged water, 98 parts by weight of methyl methacrylate, 2 parts by weight of ethylene glycol dimethacrylate, and 1 part by weight of potassium oleate were added to a separable flask. After nitrogen substitution, the temperature was raised to 60 ° C. and persulfuric acid was added. 0.2 parts by weight of potassium was added and reacted for 3 hours, and further 0.1 part by weight of potassium persulfate was added and reacted for 1 hour to obtain a resin latex.

This resin latex was dropped into an aqueous calcium chloride solution to obtain coagulated resin particles. The refractive index of the coagulated resin particles was 1.492, and the average particle size was 12 μm.
(Production of light diffusion plate)
99 parts by weight of the resin C1, 1 part by weight of the solidified resin particles, and 0.3 parts by weight of IRGANOX 1010 manufactured by Ciba Specialty Chemicals Co., Ltd. as an antioxidant were mixed to prepare a light diffusing resin composition C1. A light diffusing plate C1 having a thickness of 1.0 mm was produced in the same manner as in Example 1 except that the resin composition C1 was used instead of the resin composition A1.

  The results of evaluating the obtained light diffusion plate C1 are shown in Table 1.

(Preparation of diffusion particles)
250 parts by weight of ion-exchanged water, 55 parts by weight of methyl methacrylate, 43 parts by weight of styrene, 2 parts by weight of divinylbenzene and 1 part by weight of potassium oleate were added to a separable flask, and after nitrogen substitution, the temperature was raised to 60 ° C. Then, 0.2 part by weight of potassium persulfate was added and reacted for 3 hours, and further 0.1 part by weight of potassium persulfate was added and reacted for 1 hour to obtain a resin latex.

This resin latex was dropped into an aqueous calcium chloride solution to obtain coagulated resin particles. The coagulated resin particles had a refractive index of 1.545 and an average particle diameter of 12 μm.
(Production of light diffusion plate)
Instead of the cyclic olefin resin, 99 parts by weight of polycarbonate resin (manufactured by Teijin Chemicals Ltd .: Panlite AD5503, Tg = 145 ° C., refractive index n _D = 1.583) and 1 part by weight of the above solidified resin particles as diffusion particles Except having used, it carried out similarly to Example 1, and produced the resin sheet D1 (thickness 1.0mm).

Using this resin sheet D1, a light diffusion plate D1 having a thickness of 1.0 mm was produced in the same manner as in Example 1 except that both the temperature of the metal belt and the metal roll were set to 125 ° C.
The results of evaluating the obtained light diffusion plate D1 are shown in Table 1.

[Comparative Example 1]
A light diffusion plate a1 having a thickness of 0.5 mm was prepared in the same manner as in Example 1 except that the diffusion particles were not used and the amount of the cyclic olefin resin was changed to 100 parts by weight.

The results of evaluating the obtained light diffusion plate a1 are shown in Table 1.
[Comparative Example 2]
Resin sheet A1 was produced in the same manner as in Example 1.

  Using three rolls (surface hard chrome plating, diameter 300 mm, surface roughness 0.1 s) arranged in parallel, the resin sheet A1 was sandwiched between the rolls adjusted to 120 ° C., and 2.5 m / It picked up at the speed | rate of min and produced the 1.0-mm-thick light diffusing plate a2.

The results of evaluating the obtained light diffusion plate a2 are shown in Table 1.
[Comparative Example 3]
A resin sheet D1 (thickness: 1.0 mm) was produced in the same manner as in Example 5 except that the diffusing particles used in Example 5 were changed to the diffusing particles used in Example 1.

Using this resin sheet D, a light diffusing plate d1 having a thickness of 1.0 mm was produced in the same manner as in Example 5 except that both the temperature of the metal belt and the metal roll were set to 135 ° C.
The results of evaluating the obtained light diffusion plate d1 are shown in Table 1.

[Comparative Example 4]
The amount of the cyclic olefin-based resin is 98.8 parts by weight, and the diffusion particles are diffusion particles having an average particle diameter of 5 μm (manufactured by Sekisui Plastics Co., Ltd., trade name: Techpolymer MBX-5, refractive index n _D = 1.492).
A light diffusing plate e1 having a thickness of 1.0 mm was produced in the same manner as in Example 1 except that the amount was changed to 1.2 parts by weight. Table 1 shows the results of evaluation of the obtained light diffusing plate e.

Claims (7)

  Including the thermoplastic resin (A) and particles (B) having an average particle size of 1.5 to 20 μm, the absolute value of the difference in refractive index between the thermoplastic resin (A) and the particles (B) is 0.03 to 0.03. A resin sheet that is in the range of 0.08 and the content of the particles (B) is 0.1 to 10% by weight, a metal roll having a surface roughness of 0.3 s or less, and a surface roughness of 0. A method for producing a light diffusing plate, characterized by being sandwiched between metal belts of 3 s or less and taking off under a condition that the temperature of the metal roll is 20 to 50 ° C. lower than the glass transition temperature of the thermoplastic resin (A).   The method for producing a light diffusing plate according to claim 1, wherein a take-up speed of the resin sheet is 2 to 8 m / min.   The resin composition, wherein the resin sheet includes a thermoplastic resin (A) and particles (B) having an average particle diameter of 1.5 to 20 μm, and the content of the particles (B) is 0.1 to 10% by weight. Is a sheet obtained by melt extrusion at a temperature 100 to 150 ° C. higher than the glass transition temperature of the thermoplastic resin (A), The method for producing a light diffusing plate according to claim 1 or 2.   The method for producing a light diffusing plate according to any one of claims 1 to 3, wherein the thermoplastic resin (A) is a cyclic olefin-based resin.   Including a thermoplastic resin (A) and particles (B) having an average particle size of 1.5 to 20 μm, the content of the particles (B) is 0.1 to 10% by weight, and the residual retardation is 20 nm or less. A light diffusion plate characterized by being.   6. The light diffusing plate according to claim 5, wherein the absolute value of the difference in refractive index between the thermoplastic resin (A) and the particles (B) is in the range of 0.03 to 0.08.   The light diffusing plate according to claim 5 or 6, further comprising a fluorescent brightening agent.