JP5750245B2 - Optical film and manufacturing method thereof - Google Patents

Description

  The present invention relates to an optical film and a method for producing the same, and more particularly to an optical film used for various optical applications and a method for producing the same.

  Conventionally, optical films have been widely used in various optical applications, and such optical films are required to have excellent transparency, and depending on applications and purposes, further excellent mechanical strength and heat resistance are required. It is done.

  In order to satisfy the above physical properties, an optical film in which the monomer unit is oriented by uniaxially stretching the film after film formation is known.

  On the other hand, the optical film stretched as described above causes birefringence such as optical biaxiality due to the orientation of the monomer unit, so that it is not suitable for optical applications where the birefringence is a factor of performance degradation. is there.

  Therefore, in order to cancel the birefringence described above, for example, a norbornene-based resin and calcium carbonate fine particles are dispersed in tetrahydrofuran to prepare a polymer solution, which is applied and then dried to produce a film, and then It has been proposed to uniaxially stretch the film (see, for example, Patent Document 1).

International Publication No. 01/25364

  However, in the film proposed in Patent Document 1, the calcium carbonate fine particles may aggregate in the norbornene-based resin. In that case, the film is unsuitable for optical applications because of its reduced transparency.

  Moreover, since it is necessary to shape | mold by uniaxial stretching in order to obtain the film of patent document 1, there exists a malfunction that a manufacturing process becomes complicated and takes time. There is also a problem that the manufacturing cost increases.

  An object of the present invention is to reduce or cancel the orientation of a highly-oriented resin so that birefringence can be controlled within a desired range, while having excellent transparency, mechanical strength, and heat resistance, and its optical An object of the present invention is to provide an optical film manufacturing method capable of controlling the birefringence within a desired range with a simple method.

  In order to achieve the above object, the optical film of the present invention includes a highly oriented resin and organic-inorganic composite particles having an organic group on the surface of the inorganic particles, and the organic-inorganic composite particles have an average maximum length. Is less than 350 nm, and is characterized by being dispersed as primary particles in the highly oriented resin.

  In addition, the optical film of the present invention preferably has optical isotropy.

  Further, the method for producing an optical film of the present invention includes a step of preparing organic-inorganic composite particles having an organic group on the surface of inorganic particles and having an average maximum length of less than 350 nm. It is characterized by comprising the steps of preparing a particle-dispersed resin composition by dispersing it as primary particles in a resin, and molding an optical film from the particle-dispersed resin composition.

  In the optical film of the present invention, since the organic-inorganic composite particles are dispersed in the highly oriented resin, the orientation of the highly oriented resin in the optical film can be reduced or offset by the organic-inorganic composite particles. Therefore, it can be suitably used for optical applications in which birefringence causes performance degradation.

  In the optical film of the present invention, the organic-inorganic composite particles have an average maximum length within a specific range, and are dispersed as primary particles in the highly oriented resin, thus ensuring excellent transparency. can do.

  Further, since the optical film is obtained by molding from a particle-dispersed resin composition prepared from a highly oriented resin, it is possible to ensure excellent mechanical strength and heat resistance while eliminating the stretching step in the molding step. .

  Therefore, according to the method for producing an optical film of the present invention, specific organic-inorganic composite particles are dispersed as primary particles in a highly-oriented resin to prepare a particle-dispersed resin composition, and by molding this, The optical film can be easily produced while controlling the birefringence of the obtained optical film within a desired range. Moreover, the manufacturing cost of an optical film can be reduced.

FIG. 1 shows the birefringence relationship in the in-plane direction and thickness direction of the optical films of Examples and Comparative Examples.

  The optical film of the present invention contains a highly oriented resin and organic-inorganic composite particles.

  A highly oriented resin is defined as a resin in which an oriented monomer unit containing an aromatic ring or the like is oriented in a certain direction when formed into a film by a known method. More specifically, a highly oriented resin is defined as a resin in which an orientation unit is oriented in a certain direction in a film formed by applying a coating solution prepared by dissolving it in a solvent and stretching it. Is done.

  In addition, the degree of orientation of the highly oriented resin, that is, the degree of orientation is determined by the birefringence (ΔNxz + ΔNyz) / 2 of the film formed from the highly oriented resin and the in-plane direction (thickness direction) of the film. Birefringence ΔNxy in the direction orthogonal to

The birefringence (ΔNxz + ΔNyz) / 2 in the thickness direction of the film is, for example, 1 × 10 ⁻³ to 50 × 10 ⁻³ , preferably 5 × 10 ^{−3 to} 25 × 10 ⁻³ . Further, the birefringence ΔNxy in the in-plane direction of the film is, for example, 10 × 10 ⁻⁶ to 50 × 10 ⁻⁶ , preferably 12 × 10 ^{−6 to} 25 × 10 ⁻⁶ .

  ΔNxz is the difference between the refractive index nx in the slow axis direction (the direction in which the in-plane refractive index is maximum) x and the refractive index nz in the thickness direction z.

  ΔNyz is the difference between the refractive index ny in the fast axis direction (in the in-plane direction, the direction perpendicular to the slow axis) y and the refractive index nz in the thickness direction.

  ΔNxy is the difference between the refractive index nx in the slow axis direction x and the refractive index ny in the fast axis direction y of the film.

Specifically, in a film formed from a highly oriented resin, ΔNxz and ΔNyz are, for example, 0.5 × 10 ⁻³ to 50 × 10 ⁻³ .

  The birefringence (ΔNxy, ΔNyz, and ΔNxz) is measured by a polarization / phase difference analysis / measurement system.

  The highly oriented resin contains, for example, an aromatic ring as an oriented monomer unit, and examples of such highly oriented resin include thermoplastic resins such as polyester resin, polyimide resin, and polystyrene resin. It is done.

  Examples of the polyester resin include aromatic polyester resins such as polyarylate, polyethylene terephthalate, and polyethylene naphthalate.

  Examples of the polyimide resin include aromatic polyimide resins such as aromatic polyetherimide resins and aromatic polyamideimide resins.

  The highly oriented resin preferably includes a polyester resin and a polyimide resin, more preferably a polyester resin, and particularly preferably a polyarylate from the viewpoint of mechanical strength and heat resistance of the optical film.

  Polyarylate is, for example, a polyaryl ester obtained by an ester reaction between an aromatic dicarboxylic acid and a dihydric phenol.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, and derivatives thereof. Aromatic dicarboxylic acids can be used alone or in combination.

  Examples of the dihydric phenol include hydroquinone, 2,2-bis (p-hydroxyphenyl) propane (also known as bisphenol A), 1,1-bis (p-hydroxyphenyl) ethane, 4,4-dihydroxydiphenylmethane, and the like. And derivatives thereof. The dihydric phenol can be used alone or in combination.

  In the ester reaction, an aromatic dicarboxylic acid and a dihydric phenol are blended so that the number of moles thereof is substantially the same, and they are reacted under known reaction conditions.

  The organic-inorganic composite particles are particles having an organic group on the surface of the inorganic particles. Specifically, organic-inorganic composite particles are obtained by subjecting inorganic particles to surface treatment with an organic compound.

  Examples of inorganic compounds (inorganic raw materials) that form inorganic particles include oxides, composite oxides, carbonates, sulfates, and the like.

  An oxide is a compound of oxygen and one element other than oxygen, and is not particularly limited as one element other than oxygen (an element that combines with oxygen), for example, a group IIIb such as Sc or Y. Elements (long-period type periodic table; the same shall apply hereinafter), for example, Group IVb elements such as Ti, Zr, and Hf, Group Vb elements such as V, Nb, and Ta, for example, Group VIb such as Cr, Mo, and W Elements, for example, Group VIIb elements such as Mn, Re, for example, Group VIIIb elements such as Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, for example, Group Ib elements such as Cu, Ag, Au For example, Group IIb elements such as Zn, Cd, Hg, for example Group IIIa elements such as B, Al, Ga, In, Tl, for example Group IVa elements such as Si, Ge, Sn, Pb, for example, As, Sb, Bi, etc. a group element, for example, Te, VIa group element such as Po, for example, La, Ce, Pr, lanthanide series elements such as Nd, for example, Ac, Th, and the like actinium series elements such as U.

  Of the elements other than oxygen, a metal is preferable, and a lanthanide series element is more preferable.

Examples of the oxide include metal oxide, and preferably cerium oxide (cerium dioxide, cerium (IV) oxide, ceria: CeO ₂ ) and the like.

  The oxides can be used alone or in combination of two or more.

  The composite oxide is a compound of oxygen and a plurality of elements other than oxygen, and a plurality of elements other than oxygen (a plurality of elements that combine with oxygen) include elements other than oxygen in the above-described oxide, A combination of at least two or more selected from elements consisting of Group I elements and Group II elements can be mentioned.

  Examples of the first element include alkali metals such as Li, Na, K, Rb, and Cs. Examples of Group II elements include alkaline earth metals such as Be, Mg, Ca, Sr, Ba, and Ra.

  As a combination of a plurality of elements other than oxygen, preferably a combination of Group II elements and Group IVb elements, a combination of Group II elements and Group VIIIb elements, a combination of Group II elements and Group IVa elements, and the like, A combination containing at least a group II element can be mentioned.

  Examples of the composite oxide containing at least a Group II element include alkaline earth metal titanates, alkaline earth metal zirconates, alkaline earth metal ferrates, alkaline earth metal stannates, and the like. .

  As the complex oxide oxide, an alkaline earth metal titanate is preferably used.

The alkaline earth metal titanate, for example, titanate beryllium (BeTiO _3), magnesium titanate (MgTiO _3), calcium titanate (CaTiO _3), strontium titanate (SrTiO _3), barium titanate (BaTiO ₃ ) And radium titanate (RaTiO ₃ ).

  Complex oxides can be used alone or in combination of two or more.

The carbonate is a compound of carbonate ion (CO ₃ ²⁻ ) and a metal cation (more specifically, a compound in which a hydrogen atom of carbonic acid (H ₂ CO ₃ ) is substituted with a metal), Examples of the metal contained in the metal include alkali metals and alkaline earth metals. Examples of the alkali metal and alkaline earth metal are the same as described above.

  Among metals, an alkaline earth metal is preferable.

  Specifically, the carbonate preferably includes a carbonate containing an alkaline earth metal. Examples of such a carbonate include beryllium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, Examples thereof include radium carbonate, and preferably strontium carbonate.

  These carbonates can be used alone or in combination of two or more.

The sulfate is a compound of sulfate ion (SO ₄ ²⁻ ) and a metal cation (more specifically, a compound in which a hydrogen atom of sulfuric acid (H ₂ SO ₄ ) is substituted with a metal), Examples of the metal contained in the metal include alkali metals and alkaline earth metals. Examples of the alkali metal and alkaline earth metal are the same as described above.

  Among metals, an alkaline earth metal is preferable.

  Specifically, the sulfate preferably includes a sulfate containing an alkaline earth metal. Examples of such sulfate include beryllium sulfate, magnesium sulfate, calcium sulfate, strontium sulfate, barium sulfate, Examples thereof include radium sulfate, and preferably, barium sulfate is used.

  These sulfates can be used alone or in combination of two or more.

  The organic compound (organic raw material) is, for example, an organic group-introducing compound for introducing (arranging) an organic group on the surface of the inorganic particles, and a bonding group that can be bonded to the surface of the inorganic compound, and a bonding group Contains organic groups to be bonded.

The bonding group is appropriately selected according to the type of inorganic particles, and examples thereof include functional groups such as a carboxyl group, a phosphate group (—PO (OH) ₂ , a phosphono group), an amino group, and a sulfo group. Preferably, a carboxyl group is mentioned.

  One or more of these bonding groups are contained in the organic compound. Specifically, the linking group is bonded to the end or side chain of the organic group when the organic group is a long chain.

  The organic group includes, for example, a hydrophobic group and / or a hydrophilic group.

  As a hydrophobic group, C4-C20 hydrocarbon groups, such as an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl alkylene group, an aryl group, an aralkyl group, are mentioned, for example.

  Examples of the alkyl group include butyl, isobutyl, sec-butyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, 2-ethylhexyl, 3,3,5-trimethylhexyl, isooctyl, and nonyl. , Isononyl, decyl, isodecyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl and the like, and a linear or branched alkyl group having 4 to 20 carbon atoms. Preferably, a C6-C18 linear alkyl group is mentioned.

  Examples of the alkenyl group include alkenyl groups having 4 to 20 carbon atoms such as hexenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tetradecenyl, hexadecenyl, octadecenyl, icosenyl and the like.

  Examples of the alkynyl group include alkynyl groups having 4 to 20 carbon atoms such as hexynyl, heptynyl, octynyl, decynyl, undecynyl, dodecinyl, tridecynyl, tetradecynyl, pentadecynyl, hexadecynyl, heptadecynyl, and octadecynyl.

  Examples of the cycloalkyl group include cycloalkyl groups having 4 to 20 carbon atoms such as cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl, and cyclododecyl.

  Examples of the cycloalkenylalkylene group include C7-20 cycloalkenylalkylene groups such as norbornenedecyl (norbornyldecyl, bicyclo [2.2.1] hept-2-enyl-decyl).

  Examples of the aryl group include aryl groups having 6 to 20 carbon atoms such as phenyl, xylyl, naphthyl, and biphenyl.

  Examples of the aralkyl group include aralkyl groups having 7 to 20 carbon atoms such as benzyl, phenylethyl, phenylpropyl, phenylbutyl, phenylpentyl, phenylhexyl, phenylheptyl, diphenylmethyl and the like.

  Of the hydrophobic groups, an alkyl group, an alkenyl group, an aralkyl group, and the like are preferable, and an alkyl group and an aralkyl group are more preferable.

  When the organic group includes a hydrophobic group, the organic compound (organic group-introducing compound) is provided as a hydrophobic organic compound that imparts hydrophobicity to the inorganic particles.

  Examples of such hydrophobic organic compounds include fatty acids, and examples of such fatty acids include alkyl group-containing compounds such as saturated fatty acids (eg, hexanoic acid, decanoic acid, etc.), such as unsaturated fatty acids. Examples thereof include alkenyl group-containing compounds such as oleic acid (for example, oleic acid). Moreover, as a hydrophobic organic compound, aralkyl group containing compounds, such as aromatic carboxylic acid (for example, 6-phenylhexanoic acid), etc. are mentioned, for example.

  When the organic group includes a hydrophilic group, the organic group is a hydrophilic group-containing organic group including the hydrophilic group and the above-described hydrocarbon group bonded to the hydrophilic group.

  Examples of the hydrophilic group include a carboxyl group, a hydroxyl group, a phosphate group, an amino group, a sulfo group, and a carbonyl group. One or more hydrophilic groups are contained in the organic compound. The hydrophilic group is bonded to the end of the hydrocarbon group (the other end opposite to the one bonded to the bond) and / or the side chain.

  Examples of the hydrophilic group-containing organic group include a carboxyl group-containing organic group, a hydroxyl group-containing organic group, a phosphate group-containing organic group, an amino group-containing organic group, a sulfo group-containing organic group, and a carbonyl group-containing organic group. .

  Examples of the carboxyl group-containing organic group include carboxy hydrocarbon groups such as 3-carboxypropyl and 6-carboxyhexyl.

  Examples of the hydroxyl group-containing organic group include hydroxy hydrocarbon groups such as 4-hydroxyphenyl and 3- (4-hydroxyphenyl) propyl.

  Examples of the phosphoric acid group-containing organic group include phosphonohydrocarbon groups such as 6-phosphonohexyl.

  Examples of the amino group-containing organic group include amino hydrocarbon groups such as 6-aminohexyl.

  Examples of the sulfo group-containing organic group include a sulfo hydrocarbon group such as 6-sulfohexyl.

  Examples of the carbonyl group-containing organic group include an oxo hydrocarbon group such as 4-oxopentyl.

  When the organic group contains a hydrophilic group and a hydrocarbon group (that is, a hydrophilic group-containing organic group), the organic compound (organic group-introducing compound) is a hydrophilic organic that imparts hydrophilicity to the inorganic particles. Served as a compound.

  Examples of such hydrophilic organic compounds include carboxyl group-containing compounds such as dicarboxylic acids (eg, propanedioic acid (malonic acid), hexanedioic acid (adipic acid), etc.), such as monohydroxylcarboxylic acid (eg, Hydroxyl group-containing compounds such as 4-hydroxyphenylacetic acid, 3- (4-hydroxyphenyl) propionic acid, etc., for example, phosphoric acid group-containing compounds such as monophosphonocarboxylic acid (eg, 6-phosphonohexanoic acid, etc.) For example, an amino group-containing organic compound such as monoaminocarboxylic acid (for example, 6-aminohexanoic acid), for example, a sulfo group-containing compound such as monosulfocarboxylic acid (for example, 6-sulfohexanoic acid), for example, Carbonyl such as monocarbonylcarboxylic acid (eg 4-oxovaleric acid etc.) Etc. containing compounds.

  The organic group described above is present on the surface of the inorganic particle in the organic-inorganic composite particle. That is, the organic group covers the surface of the inorganic particles.

  The organic-inorganic composite particles described above can be obtained by subjecting an inorganic compound and the organic compound described above to a reaction treatment, preferably a high temperature treatment.

  Specifically, inorganic compounds and organic compounds are treated at high temperature in water under high pressure (hydrothermal synthesis: hydrothermal reaction), or inorganic compounds are treated at high temperature in organic compounds (high temperature treatment in organic compounds). Thus, organic-inorganic composite particles are obtained. That is, organic-inorganic composite particles are obtained by surface-treating the surface of inorganic particles formed of an inorganic compound with an organic compound.

  In hydrothermal synthesis, for example, the above-described inorganic compound and organic compound are reacted in the presence of water at a high temperature and high pressure (first hydrothermal synthesis).

  That is, first, an inorganic compound, an organic compound, and water are put into a pressure-resistant airtight container and heated to prepare a reaction system at high temperature and high pressure.

  As an inorganic compound, the same thing as the above-mentioned inorganic compound is mentioned, Preferably, an oxide or carbonate is mentioned.

  As for the blending ratio of each component, the organic compound is, for example, 5 to 160 parts by mass, preferably 10 to 110 parts by mass, and the water is, for example, 100 to 1000 parts by mass with respect to 100 parts by mass of the inorganic compound. Preferably, it is 200-700 mass parts.

  In addition, since the density of an organic compound is 0.8-1.1 g / mL normally, the compounding ratio of an organic compound is 10-150 mL with respect to 100 g of inorganic compounds, Preferably it is 20-100 mL. It is.

  Moreover, the compounding mole number of an organic compound is 0.01-1000 mol with respect to 1 mol of inorganic compounds, Preferably, it can also set to 0.1-10 mol.

  Moreover, since the density of water is about 1 g / mL normally, the mixture ratio of water is 100-1000 mL with respect to 100 g of inorganic compounds, Preferably, it is 200-700 mL.

  As for the reaction conditions in the hydrothermal reaction, specifically, the heating temperature is, for example, 100 to 500 ° C, preferably 200 to 400 ° C. Moreover, a pressure is 10-50 Mpa, for example, Preferably, it is 20-40 Mpa. The reaction time is, for example, 1 to 200 minutes, preferably 3 to 150 minutes.

  In the above reaction, the reaction product obtained mainly includes a precipitate that precipitates in water and a deposit that adheres to the inner wall of the sealed container.

  The precipitate is obtained, for example, by sedimentation separation in which the reactants are sedimented by gravity or a centrifugal field. Preferably, it is obtained as a precipitate of the reaction product by centrifugal sedimentation (centrifugation) in which sedimentation is caused by a centrifugal force field.

  Further, the deposit is collected by, for example, a spatula.

  Thereby, organic-inorganic composite particles are obtained.

  Moreover, organic-inorganic composite particles in which the inorganic compound is an oxide can be obtained by hydrothermally synthesizing the above-described element hydroxide and the organic compound (second hydrothermal synthesis).

As an element contained in a hydroxide (an element constituting a cation combined with a hydroxide ion (OH ⁻ ), specifically, a metal), an element similar to an element other than oxygen in the oxide described above may be used. Preferably, IVb group element, IIIa group element, and a lanthanide series element are mentioned.

Specific examples of the hydroxide include titanium hydroxide (Ti (OH) ₄ ), aluminum hydroxide (Al (OH) ₃ ), cerium hydroxide (Ce (OH) ₄ ), and the like.

  Examples of the organic compound include the same organic compounds used in the first hydrothermal synthesis described above.

  In the second hydrothermal synthesis, the hydroxide and the organic compound are reacted in the presence of water at high temperature and high pressure.

  The compounding ratio of each component is, for example, 4 to 550 parts by mass, preferably 15 to 330 parts by mass with respect to 100 parts by mass of hydroxide, and water is, for example, 50 to 2500 parts by mass. Preferably, it is 100-500 mass parts.

  Moreover, the compounding ratio of the organic compound is, for example, 5 to 500 mL, preferably 20 to 300 mL with respect to 100 g of the hydroxide, and the compounding mole number of the organic compound is, for example, with respect to 1 mol of the hydroxide. 0.01 to 10000 mol, preferably 0.1 to 10 mol.

  Moreover, the mixture ratio of water is 50-2500 mL with respect to 100 g of hydroxides, Preferably, it is 100-500 mL.

  The reaction conditions in the second hydrothermal synthesis are the same as the reaction conditions in the first hydrothermal synthesis described above.

  Thereby, organic-inorganic composite particles are obtained.

  In addition, in the above-described second hydrothermal synthesis prescription, by adding a carbonic acid source in addition to each component, organic-inorganic composite particles in which the inorganic compound is a carbonate can also be obtained (third hydrothermal Synthesis).

  Examples of the carbonic acid source include formic acid and / or urea.

  As the hydroxide, the same hydroxide as exemplified in the second hydrothermal synthesis described above is used. As the organic compound, the same organic compound as exemplified in the first hydrothermal synthesis described above is used.

  In the third hydrothermal synthesis, a hydroxide, a carbonic acid source, and an organic compound are reacted in the presence of water at high temperature and high pressure.

  The mixing ratio of the carbonic acid source is, for example, 5 to 140 parts by mass, preferably 10 to 70 parts by mass with respect to 100 parts by mass of the hydroxide.

  In addition, since the density of a carbonic acid source is 1.1-1.4 g / mL normally, the compounding ratio of a carbonic acid source is 5-100 mL with respect to 100 g of hydroxides, Preferably, it is 10- 50 mL. In addition, the number of moles of the carbonic acid source is, for example, 0.4 to 100 moles, preferably 1.01 to 10.0 moles, and more preferably 1.05 to 1 moles per mole of hydroxide. It can also be set to 30 moles. The blending ratio of hydroxide, organic compound and water is the same as those blending ratio in the second hydrothermal synthesis described above.

  The reaction conditions in the third hydrothermal synthesis are the same as the reaction conditions in the first hydrothermal synthesis described above.

  Furthermore, organic-inorganic composite particles in which the inorganic compound is a carbonate can also be obtained by hydrothermal synthesis of a hydroxide, a metal complex, and an organic compound (fourth hydrothermal synthesis).

  As a hydroxide, the thing similar to the hydroxide illustrated by the 2nd hydrothermal synthesis is mentioned. Moreover, as an organic compound, the thing similar to the organic compound illustrated by the 1st hydrothermal synthesis is mentioned.

  The metal element contained in the metal complex is an element that forms a complex oxide with the element and oxygen contained in the above hydroxide, and examples thereof include metals such as titanium, iron, tin, and zirconium. Preferably, titanium is used.

  Examples of the ligand of the metal complex include monohydroxycarboxylic acids such as 2-hydroxyoctanoic acid.

  Examples of the metal complex include 2-hydroxyoctanoic acid titanate. The metal complex can be obtained from the above metal element and ligand by a known method.

  Examples of the organic compound include the same organic compounds used in the first hydrothermal synthesis described above.

  In the fourth hydrothermal synthesis, the above-described hydroxide, metal complex, and organic compound are reacted in the presence of water at high temperature and high pressure.

  The compounding ratio of each component is, for example, 1 to 50 parts by mass, preferably 5 to 30 parts by mass of the hydroxide, and 4 to 550 parts by mass of the organic compound with respect to 100 parts by mass of the metal complex. Parts, preferably 15 to 330 parts by weight, and water is, for example, 200 to 1000 parts by weight, preferably 300 to 700 parts by weight.

  In addition, the compounding ratio of the organic compound is, for example, 5 to 500 mL, preferably 20 to 300 mL, with respect to 100 g of the metal complex, and the compounding mole number of the organic compound is 0.00 with respect to 1 mol of the hydroxide. It can also be set to 01-1000 mol.

  Moreover, the mixture ratio of water is 200-1000 mL with respect to 100 g of metal complexes, Preferably, it is 300-700 mL.

  The reaction conditions for the fourth hydrothermal synthesis are the same as the reaction conditions for the first hydrothermal synthesis described above.

  Furthermore, the above-described hydrothermal synthesis (first to fourth hydrothermal synthesis) can be performed in the presence of a pH adjusting agent.

  Examples of the pH adjuster include alkali and acid.

  Examples of the alkali include inorganic alkalis such as potassium hydroxide and sodium hydroxide, and organic alkalis such as ammonia. Examples of the acid include inorganic acids such as sulfuric acid, nitric acid, and hydrochloric acid, and organic acids such as formic acid and acetic acid.

  Preferably, alkali is used.

  The pH of the reaction system is set to 8 to 12, for example, with a pH adjuster.

  Thereby, the average L (described later) of the maximum length of the obtained organic-inorganic composite particles can be set to a desired range, more specifically, a smaller value. Therefore, organic-inorganic composite particles having a small size (specifically, an average L of the maximum length described later) can be suitably used for optical applications.

  Examples of the inorganic compound subjected to the high-temperature treatment in the organic compound include the same inorganic compounds as described above.

  In the high temperature treatment in an organic compound, an inorganic compound and an organic compound are blended and, for example, they are heated under normal pressure.

  The compounding ratio of the organic compound is, for example, 10 to 10,000 parts by mass, preferably 100 to 1000 parts by mass with respect to 100 parts by mass of the inorganic compound. Moreover, the compounding ratio of the organic compound based on volume is, for example, 10 to 10000 mL, preferably 100 to 1000 mL with respect to 100 g of the inorganic compound.

  The heating temperature is, for example, a temperature exceeding 100 ° C., preferably 125 ° C. or more, more preferably 150 ° C. or more, and usually, for example, 300 ° C. or less, preferably 275 ° C. or less. The heating time is, for example, 1 to 60 minutes, preferably 3 to 30 minutes.

  Thereafter, the organic-inorganic composite particles obtained by the above-described first to fourth hydrothermal synthesis or high-temperature treatment in an organic compound are washed and / or wet classified as necessary.

  In order to wash the organic-inorganic composite particles, for example, a solvent is added to the organic-inorganic composite particles obtained by the first to fourth hydrothermal synthesis or high-temperature treatment in the organic compound to wash the unreacted organic compound. (That is, the organic compound is dissolved in a solvent), and then the solvent is removed and recovered (separated).

  Examples of the solvent include alcohols such as methanol, ethanol, propanol, and isopropanol, ketones such as acetone, methyl ethyl ketone, cyclohexanone, and cyclopentanone, and aliphatic hydrocarbons such as pentane, hexane, and heptane (specifically, Halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and trichloroethane, halogenated aromatic hydrocarbons such as chlorobenzene and dichlorobenzene, ethers such as tetrahydrofuran, such as benzene, toluene, and xylene And aromatic hydrocarbons. Preferably, alcohol is used.

  The organic-inorganic composite particles after washing are separated and recovered from the solvent (supernatant liquid), for example, by filtration, decantation, or the like. Thereafter, if necessary, the recovered material is dried by, for example, heating or airflow.

  In order to wet-classify the organic-inorganic composite particles, for example, the organic-inorganic composite particles obtained by the above-described first to fourth hydrothermal synthesis or high-temperature treatment in an organic compound, or the above-described washing A solvent is added to the organic-inorganic composite particles, and they are stirred and then allowed to stand, or separated into a supernatant and a precipitate by centrifugal sedimentation. Examples of the solvent include the same solvents as described above, and preferably halogenated aliphatic hydrocarbons.

  Thereafter, the top is collected.

  In wet classification, the supernatant after recovery can be further filtered. For the filtration, for example, a filter having an opening diameter of 500 nm or less, preferably 400 nm or less, and usually 1 nm or more is used.

  Thereafter, the solvent is removed from the recovered material to obtain organic-inorganic composite particles.

  Organic-inorganic composite particles having a small size can be obtained by wet classification.

  And the average L of the maximum length (length in the longitudinal direction) of the organic-inorganic composite particles (primary particles) obtained as described above is less than 350 nm, preferably 300 nm or less, more preferably 200 nm or less, particularly preferably For example, it is 10 nm or more, preferably 20 nm or more. The average S of the minimum length (length in the short direction) of the organic-inorganic composite particles is, for example, 1 nm to 100 nm, preferably 5 nm to 50 nm.

  The average particle diameter D of the organic-inorganic composite particles is, for example, 400 nm or less, preferably 300 nm or less, more preferably 200 nm or less, particularly preferably 100 nm or less, and usually, for example, 1 nm or more, preferably 2 nm or more.

  The aspect ratio A of the organic-inorganic composite particles is, for example, 1000 or less, preferably 100 or less, preferably less than 1.5, and usually 1 or more.

  The size (average L of maximum length, average S of minimum length, average particle diameter D, and aspect ratio A) of the organic-inorganic composite particles is measured by a known method, and specifically, detailed in later examples. As stated, measured by FE-TEM and / or FE-SEM.

  If the average L of the maximum length of the organic-inorganic composite particles exceeds the specific range described above, the orientation of the highly oriented resin cannot be reduced and offset. Moreover, when mixing with highly oriented resin, an organic inorganic composite particle may be crushed.

  On the other hand, if the average L of the maximum length of the organic-inorganic composite particles is less than the specific range described above, the physical strength of the optical film may be lowered.

  In addition, when the aspect ratio A of the organic-inorganic composite particles exceeds the above range, the organic-inorganic composite particles themselves may be oriented, making it difficult to control the birefringence (orientation) of the optical film.

  Further, the shape (outer shape) of the organic-inorganic composite particles (primary particles) is not particularly limited, and is, for example, a substantially rectangular parallelepiped shape such as a substantially cubic shape, for example, a substantially spherical shape, for example, a substantially long sphere (or a spindle shape). ), A spheroidal shape such as a substantially oblate ball, for example, a needle-like shape or a rod-like shape. Preferably, it has a substantially cubic shape or a substantially spherical shape. If it is a substantially cubic shape or a substantially spherical shape, the aspect ratio A can be reliably set in the above-described range.

  The organic-inorganic composite particles have, for example, the above-described solid shape or hollow shape (specifically, a hollow substantially spherical shape, a hollow substantially cubic shape, or the like).

  The organic-inorganic composite particles obtained in this way are difficult to aggregate in the dry state. Even if the organic inorganic composite particles apparently aggregate in the dry state, they are aggregated (formation of secondary particles) in the optical film described below. ) Is surely prevented, and is dispersed almost uniformly as primary particles in the highly oriented resin.

  The birefringence Δn of the organic-inorganic composite particles obtained by the various methods described above is not particularly limited, and when it is positive, for example, 0.001 to 0.200, preferably 0.010 to 0 When it is .200 and is negative, it is, for example, -0.200 to -0.001, preferably -0.200 to -0.010.

  Note that the birefringence Δn of the organic-inorganic composite particles is substantially the same as the birefringence of the inorganic particles. Therefore, the birefringence Δn of the organic-inorganic composite particles is calculated from the refractive index of the inorganic particles described in a known document (for example, Chemical Dictionary) Alternatively, it is considered and calculated from the crystal structure of the inorganic particles.

  Next, an embodiment of the method for producing the optical film of the present invention for obtaining the optical film of the present invention will be described.

  In this method, first, in accordance with the above, organic-inorganic composite particles having an average length L of a specific range are prepared, and then the organic-inorganic composite particles are dispersed as primary particles in a highly-oriented resin. A dispersed resin composition is prepared.

  In order to disperse the organic-inorganic composite particles as primary particles in the highly-oriented resin, for example, a solvent, the organic-inorganic composite particles, and the highly-oriented resin are mixed and stirred (solution preparation). The particle-dispersed resin composition thus prepared is a varnish (solution) of the particle-dispersed resin composition containing a solvent.

  Examples of the solvent include, but are not limited to, for example, the same solvents as those exemplified in the above-described washing, and in addition to these, for example, alicyclic hydrocarbons such as cyclopentane and cyclohexane (specifically, And cycloalkane), for example, esters such as ethyl acetate, polyols such as ethylene glycol and glycerin, and nitrogen-containing compounds such as N-methylpyrrolidone, pyridine, acetonitrile and dimethylformamide.

  These solvents can be used alone or in combination of two or more. Preferred examples of the solvent include ketones, aromatic hydrocarbons, and halogenated aliphatic hydrocarbons.

  Specifically, in order to prepare the particle-dispersed resin composition, first, the above-described solvent and the highly oriented resin are blended, and the highly oriented resin is dissolved in the solvent to prepare a resin solution. Thereafter, the resin solution and the organic-inorganic composite particles are blended and stirred to prepare a particle-dispersed resin composition (first preparation method).

  In the particle-dispersed resin composition, the organic-inorganic composite particles are dispersed as primary particles in a solvent and a highly oriented resin.

  The blending ratio of the highly oriented resin is, for example, 40 parts by mass or less, preferably 20 parts by mass or less, and usually 1 part by mass or more with respect to 100 parts by mass of the resin solution.

  If the blending ratio of the highly oriented resin is within the above range, the highly oriented resin can be surely dissolved in the resin solution.

  The compounding ratio of the organic / inorganic composite particles is, for example, 10 to 1000 parts by mass, or preferably 40 to 200 parts by mass with respect to 100 parts by mass of the solid content (highly oriented resin) of the resin solution. Moreover, the compounding ratio of the organic / inorganic composite particles is, for example, 1 to 50 parts by mass, preferably 2 to 35 parts by mass with respect to 100 parts by mass of the total amount of the resin solution (total amount of highly oriented resin and solvent). .

  When the blending ratio of the organic / inorganic composite particles is less than the above range, the orientation of the highly oriented resin may not be sufficiently reduced and offset. On the other hand, when the mixing ratio of the organic-inorganic composite particles exceeds the above range, the dispersibility of the organic-inorganic composite particles may be lowered.

  Also, a solvent and organic-inorganic composite particles are blended, and the organic-inorganic composite particles are dispersed in the solvent to prepare a particle dispersion, and then the particle dispersion and the highly-oriented resin are blended. The particle-dispersed resin composition can also be prepared by stirring (second preparation method).

  In the particle dispersion, the organic-inorganic composite particles are dispersed as primary particles in a solvent.

  The compounding ratio of the organic-inorganic composite particles is, for example, 0.1 to 50 parts by mass, preferably 1 to 10 parts by mass with respect to 100 parts by mass of the particle dispersion.

  When the blending ratio of the organic / inorganic composite particles is less than the above range, the orientation of the highly oriented resin may not be sufficiently reduced and offset. On the other hand, when the mixing ratio of the organic-inorganic composite particles exceeds the above range, the dispersibility of the organic-inorganic composite particles may be lowered.

  The blending ratio of the highly oriented resin is, for example, 100 to 1000 parts by mass, preferably 50 to 200 parts by mass with respect to 100 parts by mass of the solid content (organic-inorganic composite particles) of the particle dispersion.

  If the blending ratio of the highly oriented resin is in the above range, good dispersibility of the organic-inorganic composite particles in the highly oriented resin and the solvent can be ensured.

  Furthermore, for example, a particle-dispersed resin composition can also be prepared by blending a solvent, organic-inorganic composite particles, and a highly-oriented resin at once and stirring them (third preparation method).

  The blending ratio of each component is, for example, 0.1 to 60 parts by mass, preferably 1 to 40 parts by mass, and highly oriented with respect to 100 parts by mass of the total amount of the particle-dispersed resin composition. For example, 40 parts by mass or less, preferably 20 parts by mass or less, and usually 1 part by mass or more. Further, the blending ratio of the solvent is the balance of the organic-inorganic composite particles and the highly oriented resin in the particle-dispersed resin composition.

  When the blending ratio of the organic / inorganic composite particles is less than the above range, the orientation of the highly oriented resin may not be sufficiently reduced and offset. On the other hand, when the mixing ratio of the organic-inorganic composite particles exceeds the above range, the dispersibility of the organic-inorganic composite particles may be lowered.

  If the blending ratio of the highly oriented resin is in the above range, good dispersibility of the organic-inorganic composite particles in the highly oriented resin and the solvent can be ensured.

  Furthermore, in order to prepare the particle-dispersed resin composition, for example, the resin can be melted by heating and blended with organic-inorganic composite particles without blending a solvent (fourth preparation method).

  The particle-dispersed resin composition thus prepared is a melt of the particle-dispersed resin composition that does not contain a solvent.

  The compounding ratio of the organic-inorganic composite particles with respect to 100 parts by mass of the highly oriented resin is, for example, 10 to 1000 parts by mass, preferably 20 to 500 parts by mass.

  The heating temperature is the same as or higher than the melting temperature of the highly oriented resin, specifically 200 to 350 ° C.

  Next, in this method, an optical film is formed from the particle-dispersed resin composition.

  Specifically, an optical film is formed by applying a particle-dispersed resin composition.

  That is, when the particle-dispersed resin composition is prepared by the first to third preparation methods described above, the particle-dispersed resin composition is applied on a known support plate to produce a coating film. The particle-dispersed resin composition is formed on a film by drying the coating film.

  In the application of the particle-dispersed resin composition, for example, a known application method such as a spin coater method or a bar coater method is used. In the application of the particle-dispersed resin composition, the solvent is removed by volatilization simultaneously with or immediately after the application. If necessary, the solvent can be dried by heating after coating.

  Moreover, a coating film is formed into a film, without implementing an extending | stretching process.

  When the particle-dispersed resin composition is prepared by the fourth preparation method, the particle-dispersed resin composition is formed into a film by a melt molding method in which the particle-dispersed resin composition is extruded using an extruder or the like. A membrane can also be formed. The particle-dispersed resin composition is formed into a film without performing a stretching process.

  Thus, the thickness d of the optical film shape | molded is suitably set according to desired optical characteristics (phase difference R etc. which are mentioned later), for example, 1-1000 micrometers, Preferably, it is 5-500 micrometers. The thickness d of the optical film is measured with a known film thickness meter.

  In the optical film thus formed, since the organic-inorganic composite particles are dispersed as primary particles in the highly-oriented resin, the orientation of the highly-oriented resin is disturbed by the organic-inorganic composite particles (inhibition). This can reduce or offset the orientation of the highly oriented resin. Therefore, it can be suitably used for optical applications in which birefringence causes performance degradation.

  That is, the highly oriented resin and the organic / inorganic composite particles are selected from the above-described examples so that the birefringence of the optical film falls within the following range.

In-plane birefringence ΔNxy: for example, 200 × 10 ⁻⁶ or less, preferably 100 × 10 ⁻⁶ or less, preferably 50 × 10 ⁻⁶ or less, more preferably 20 × 10 ⁻⁶ or less, usually 0 or more Birefringence in the thickness direction (ΔNxz + ΔNyz) / 2: For example, 12 × 10 ⁻³ or less, preferably 10 × 10 ⁻³ or less, more preferably 5.0 × 10 ⁻³ or less, and particularly preferably 2 0.0 × 10 ⁻³ or less, most preferably 1.0 × 10 ⁻³ or less, usually 0 or more Further, if the birefringence of the optical film is the following value, the optical film has optical isotropy. Can be granted.

In-plane birefringence ΔNxy: substantially 0
Birefringence in thickness direction (ΔNxz + ΔNyz) / 2: substantially 0
An optical film having substantially zero birefringence can exhibit optical isotropy, and exhibits a property that does not have a practical effect on such optical characteristics.

Specifically, the range includes birefringence ΔNxy in the in-plane direction, for example, 20 × 10 ⁻³ or less, and birefringence in the thickness direction (ΔNxz + ΔNyz) / 2, for example, 2.0 × 10 ^{− 3} or less.

  The birefringence ΔNxy in the in-plane direction of the optical film and the birefringence in the thickness direction (ΔNxz + ΔNyz) / 2 are measured and calculated by a polarization / phase difference analysis / measurement system.

  More specifically, the above-described birefringence is calculated according to the following equation from the phase difference R measured by the polarization / phase difference analysis / measurement system and the thickness d of the optical film.

In-plane birefringence ΔNxy = (in-plane phase difference Re) / (thickness d)
Birefringence in thickness direction (ΔNxz + ΔNyz) / 2 = (Thickness direction retardation Rth) / (Thickness d)
Moreover, the haze of the optical film in thickness 10-25 micrometers is 3% or less, for example, Preferably, it is 1.5% or less, and is 0.01% or more normally. When the haze of an optical film exceeds the said range, it may become unsuitable as an optical film.

  The haze is measured using a haze meter.

  An optical application in which this optical film is used is, for example, an optical application in which birefringence is a factor in performance degradation, and more specifically, a liquid crystal display or the like. Preferably, a cell of a liquid crystal panel is used. Examples include substrates and transparent protective films for polarizing plates.

  The optical application is more preferably an optical application requiring optical isotropy. Examples of such an optical application include a cell substrate of a liquid crystal substrate and a transparent protective film of a polarizing plate.

  Further, in the above-described optical film, the organic-inorganic composite particles have excellent transparency because the average L of the maximum length is in the specific range described above and is dispersed as primary particles in the highly oriented resin. Can be secured.

  Moreover, since an optical film is obtained by shape | molding a particle-dispersed resin composition in the manufacturing process, it can ensure the outstanding mechanical strength and heat resistance, making the extending | stretching process in a shaping | molding process unnecessary.

  Therefore, according to the above-described method, the optical film can be easily made while applying the particle-dispersed resin composition and molding without stretching, while controlling the birefringence of the obtained optical film to the above-described desired range. Can be manufactured. Moreover, the manufacturing cost of an optical film can be reduced.

  Preparation Examples, Comparative Preparation Examples, Examples and Comparative Examples are shown below to further illustrate the present invention, but the present invention is not limited to them.

In addition, the evaluation method of organic-inorganic composite particle | grains, an inorganic particle, and an optical film is described below.
(1) X-ray diffraction method (XRD)
Organic-inorganic composite particles and inorganic particles are filled in glass folders, respectively, and X-ray diffraction is performed under the following conditions. Then, the component of the inorganic compound by database search is assigned from the obtained peak.

X-ray diffractometer: D8 DISCOVER with GADDS, manufactured by Bruker AXS (incident side optical system)
-X-ray source: CuKα (λ = 1.542 mm), 45 kV, 360 mA
Spectrometer (monochromator): Multilayer mirror Collimator diameter: 300 μm
(Receiving side optical system)
Counter: Two-dimensional PSPC (Hi-STAR)
・ Distance between organic / inorganic composite particles (and inorganic particles) and counter: 15 cm
・ 2θ = 20, 50, 80 degrees, ω = 10, 25, 40 degrees, Phi = 0 degree, Psi = 0 degrees ・ Measurement time: 10 minutes ・ Attribution (semi-quantitative software): FPM EVA, manufactured by Bruker AXS ( 2) Fourier transform infrared spectrophotometry (FT-IR)
Fourier transform infrared spectrophotometry is performed by the KBr method using the following apparatus.

Fourier transform infrared spectrophotometer: FT / IRplus, manufactured by JASCO (3) Shape and size of organic-inorganic composite particles and inorganic particles (a) Electron emission type transmission electron microscope (FE-TEM)
Organic-inorganic composite particles and inorganic particles are dispersed on a Cu mesh with a carbon support film, and photographed with an electrolytic emission transmission electron microscope (FE-TEM).

  And from the obtained FE-TEM photograph, while observing the shape of organic-inorganic composite particles and inorganic particles, and measuring the average of the maximum length (L) and the average of the minimum length (S), from them An aspect ratio (A) is calculated.

FE-TEM: HF2000, Hitachi, Ltd. Acceleration voltage: 200kV
(B) Electrolytic emission scanning electron microscope (FE-SEM)
Organic-inorganic composite particles and inorganic particles are dispersed on a sample stage, respectively, and then coated with osmium to prepare a sample. Subsequently, the produced sample is photographed with the following electrolytic emission scanning electron microscope (FE-SEM).

  And from the obtained FE-SEM photograph, while observing the shape of organic-inorganic composite particles and inorganic particles, and measuring the average of the maximum length (L) and the average of the minimum length (S), from them An aspect ratio (A) is calculated.

FE-SEM: JSM-7500F, manufactured by JEOL Ltd. Acceleration voltage: 2 kV
(4) Transparency (haze)
The transparency of the optical film is evaluated by measuring the haze of the optical film using a haze meter (Murakami Color Research Laboratory Co., Ltd.).
(5) Thickness of optical film The thickness (d) of the optical film is measured with a film thickness meter (DIGIMICRO, manufactured by Nikon Corporation).
(6) Birefringence and retardation (a) Birefringence of organic-inorganic composite particles and inorganic particles The birefringence (Δn) of organic-inorganic composite particles and inorganic particles is described in Chemical Dictionary (Kyoritsu Publishing Co., Ltd., published in 1997). It calculates from the refractive index of the inorganic particle to be calculated, or calculates from the crystal structure of the inorganic particle.
(B) Birefringence and retardation of optical film The birefringence (ΔN) and retardation (R) of the optical films of Examples 1 to 5 and Comparative Examples 1, 3, and 4 were calculated using the Mueller matrix polarimeter (Axoacan, AXOMETRICS). Measured).

  In addition, the birefringence (ΔNxy) in the in-plane direction and the birefringence ((ΔNxz + ΔNyz) / 2) in the thickness direction of the optical film are calculated based on the following equations.

In-plane birefringence ΔNxy = in-plane phase difference Re / thickness d
Thickness direction birefringence [(ΔNxz + ΔNyz) / 2] = Thickness direction retardation Rth / Thickness d
Further, based on the above-described birefringence in the in-plane direction and birefringence in the thickness direction, optical characteristics (optical isotropic or uniaxial) are evaluated.

  In addition, about the optical film of the comparative example 2, it originated in the aggregation of the inorganic particle and it became cloudy, Therefore, birefringence and phase difference were not able to be measured and calculated.

(Preparation of organic-inorganic composite particles)
Preparation Example 1
(First hydrothermal synthesis)
A 5 mL high-pressure reactor (manufactured by AKICO) was charged with 0.5 g of strontium carbonate (manufactured by Honjo Chemical Co., Ltd.), 0.3503 mL of 6-phenylhexanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 3.403 mL of pure water.

  Next, the lid of the high-pressure reactor is closed, heated to 300 ° C. in a shaking heating furnace (manufactured by AKICO), the interior of the high-pressure reactor is pressurized to 30 MPa, and shaken for 10 minutes, thereby hydrothermal synthesis. did.

  Thereafter, rapid cooling was performed by putting the high-pressure reactor into cold water.

  Next, ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred, and centrifuged at 12000 G for 10 minutes with a centrifuge (trade name: MX-301, manufactured by Tommy Seiko Co., Ltd.), and then a precipitate (reaction) Product) was separated from the supernatant. This washing operation was repeated 5 times to remove the remaining 6-phenylhexanoic acid, and ethanol was distilled off from the precipitate to obtain organic-inorganic composite particles (washing step).

  Next, 0.1 g of washed organic-inorganic composite particles and 30 g of chloroform were charged into a 50 mL screw tube bottle.

  Next, after stirring them with a spatula, they were separated into a supernatant and a precipitate by centrifuging at 2000 G for 5 minutes in a centrifuge (trade name: MX-301, manufactured by Tommy Seiko Co., Ltd.) .

  Subsequently, the supernatant was taken out, the taken-out supernatant was filtered with a filter having an opening diameter of 100 nm, and the filtrate was dried to obtain organic-inorganic composite particles having a small particle size.

  Then, said organic-inorganic composite particle | grains evaluated said (1) XRD, (2) FT-IR, (3) (b) FE-SEM, and (6) (a) birefringence, respectively.

As a result, (1) XRD confirmed that the inorganic compound forming the inorganic particles was SrCO ₃ .

  In (2) FT-IR, it was confirmed that an aralkyl group (6-phenylhexyl group) was present on the surface of the inorganic particles.

  Furthermore, in (3) (b) FE-SEM, the shape of the organic-inorganic composite particles is oblong or spherical, the average maximum length (L) of the organic-inorganic composite particles is 70 nm, and the average minimum length (S ) 40 nm, and the aspect ratio (A) was 1-2.

  Furthermore, (6) (a) The birefringence (Δn) of the organic-inorganic composite particles is calculated as -0.14 from the refractive index of strontium carbonate described in the Chemical Dictionary (Kyoritsu Publishing Co., Ltd., published in 1997). did.

Preparation Example 2
In a 5 mL high-pressure reactor (manufactured by AKICO), 0.545 g of cerium oxide (manufactured by Wako Pure Chemical Industries, Ltd.), 0.1639 mL of hexanoic acid (manufactured by Wako Pure Chemical Industries, Ltd.), 0.2591 mL of decanoic acid (manufactured by Wako Pure Chemical Industries, Ltd.) And 1.649 mL of pure water were charged.

  Next, the lid of the high-pressure reactor is closed, heated to 400 ° C. in a shaking-type heating furnace (manufactured by AKICO), the inside of the high-pressure reactor is pressurized to 40 MPa, and shaken for 10 minutes, thereby hydrothermal synthesis. did.

  Thereafter, rapid cooling was performed by putting the high-pressure reactor into cold water.

  Next, ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred, and centrifuged at 12000 G for 10 minutes with a centrifuge (trade name: MX-301, manufactured by Tommy Seiko Co., Ltd.), and then a precipitate (reaction) Product) was separated from the supernatant (washing step). This washing operation was repeated 5 times to remove the remaining hexanoic acid and decanoic acid, and ethanol was distilled off from the precipitate to obtain organic-inorganic composite particles.

  Next, 0.1 g of washed organic-inorganic composite particles and 30 g of chloroform were charged into a 50 mL screw tube bottle.

  Next, after stirring them with a spatula, they were separated into a supernatant and a precipitate by centrifuging at 2000 G for 5 minutes in a centrifuge (trade name: MX-301, manufactured by Tommy Seiko Co., Ltd.) .

  Next, the supernatant was taken out and dried to obtain organic-inorganic composite particles.

  Then, about the obtained organic inorganic composite particle, said (1) XRD, (2) FT-IR, (3) (a) FE-TEM, and (6) (a) birefringence were evaluated, respectively.

As a result, in (1) XRD, inorganic compound forming the inorganic particles were confirmed to be CeO _2.

  In (2) FT-IR, it was confirmed that alkyl groups (hexyl group and decyl group) were present on the surface of the inorganic particles.

  Further, (3) (a) In the FE-TEM, the shape of the organic-inorganic composite particles is a substantially rectangular parallelepiped, the average maximum length (L) of the organic-inorganic composite particles is 6 nm, and the average minimum length (S) Was 7 nm and the aspect ratio (A) was 1-2.

  Furthermore, the birefringence (Δn) of (6) (a) organic-inorganic composite particles was calculated as 0 from the crystal structure of cerium oxide (cubic system, fluorite structure).

Preparation Example 3
(First hydrothermal synthesis)
A 5 mL high-pressure reactor (manufactured by AKICO) was charged with 0.5 g of barium sulfate, 0.3503 mL of 6-phenylhexanoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) and 3.403 mL of pure water.

  Next, the lid of the high-pressure reactor is closed, heated to 300 ° C. in a shaking heating furnace (manufactured by AKICO), the interior of the high-pressure reactor is pressurized to 30 MPa, and shaken for 10 minutes, thereby hydrothermal synthesis. did.

  Thereafter, rapid cooling was performed by putting the high-pressure reactor into cold water.

  Next, ethanol (manufactured by Wako Pure Chemical Industries, Ltd.) was added and stirred, and centrifuged at 12000 G for 10 minutes with a centrifuge (trade name: MX-301, manufactured by Tommy Seiko Co., Ltd.), and then a precipitate (reaction) Product) was separated from the supernatant. This washing operation was repeated 5 times to remove the remaining 6-phenylhexanoic acid, and ethanol was distilled off from the precipitate to obtain organic-inorganic composite particles (washing step).

  Next, 0.1 g of washed organic-inorganic composite particles and 30 g of chloroform were charged into a 50 mL screw tube bottle.

  Next, after stirring them with a spatula, they were separated into a supernatant and a precipitate by centrifuging at 2000 G for 5 minutes in a centrifuge (trade name: MX-301, manufactured by Tommy Seiko Co., Ltd.) .

  Subsequently, the supernatant was taken out, the taken-out supernatant was filtered with a filter having an opening diameter of 100 nm, and the filtrate was dried to obtain organic-inorganic composite particles having a small particle size.

  Then, about the obtained organic inorganic composite particle, said (1) XRD, (2) FT-IR, (3) (a) FE-TEM, and (6) (a) birefringence were evaluated, respectively.

As a result, (1) XRD confirmed that the inorganic compound forming the inorganic particles was BaSO ₄ .

  In (2) FT-IR, it was confirmed that an aralkyl group (6-phenylhexyl group) was present on the surface of the inorganic particles.

  Further, (3) (a) In the FE-TEM, the shape of the organic-inorganic composite particles is oblong or spherical, the average maximum length (L) of the organic-inorganic composite particles is 30 nm, and the average minimum length (S ) 10 nm, and the aspect ratio (A) was 1-2.

  Furthermore, (6) (a) The birefringence (Δn) of the organic-inorganic composite particles was calculated as 0.012 from the crystal structure (orthorhombic system) of barium sulfate.

(Preparation of inorganic particles)
Comparative Preparation Example 1
The strontium carbonate (Honjo Chemical Co., Ltd.) charged in Preparation Example 1 was used as inorganic particles in Comparative Preparation Example 1 as it was.

  The inorganic particles were evaluated for (3) (b) FE-SEM and (6) (a) birefringence.

  As a result, in (3) (b) FE-SEM, the shape of the inorganic particles is acicular, the average maximum length (L) of the inorganic particles is 350 nm, and the average minimum length (S) is 70 nm. The aspect ratio (A) was 2-8.

  The birefringence (Δn) of the inorganic particles (6) (a) was calculated as −0.14 from the refractive index of strontium carbonate described in the Chemical Dictionary (published by Kyoritsu Publishing Co., Ltd., published in 1997). .

  Table 1 shows the formulation and evaluation of Preparation Examples 1 to 3 and Comparative Preparation Example 1.

(Preparation of optical film)
Example 1
(First preparation method)
According to the formulation described in Table 2, a solvent, a highly oriented resin, and organic-inorganic composite particles were blended to prepare a particle-dispersed resin composition.

  That is, 42.5 parts by mass of cyclopentanone and 42.5 parts by mass of toluene as a solvent and 15 parts by mass of polyarylate (product name: PAR T-6, manufactured by Nitto Denko Corporation) were blended to prepare polyarylate. A resin solution was prepared by dissolving in cyclopentanone and toluene. Thereafter, 100 parts by mass of this resin solution and 15 parts by mass of the organic-inorganic composite particles of Preparation Example 1 were blended, and these were stirred with an ultrasonic wave to prepare a varnish of the particle-dispersed resin composition.

  Thereafter, the particle-dispersed resin composition was applied onto a support plate by a bar coater method, and then the solvent was naturally dried to form an optical film.

  Thereafter, the obtained optical film was measured for (4) transparency (haze), (5) thickness, (6) (b) birefringence and retardation.

  The results are shown in Table 2.

Examples 2-5 and Comparative Examples 1-4
In the same manner as in Example 1, a particle-dispersed resin composition was prepared according to the formulation described in Table 1, and subsequently the particle-dispersed resin composition was applied and dried to form an optical film.

  In addition, about the comparative example 1, the solvent and highly oriented resin were mix | blended without mix | blending organic inorganic composite particle | grains, the varnish of the resin composition was prepared, and the resin composition was formed into a film on the optical film.

  Then, about the optical film of Examples 2-5 and Comparative Examples 1-4, it carried out similarly to Example 1, (4) Transparency (haze), (5) Thickness, (6) (b) Birefringence and position The phase difference was measured.

  In Comparative Example 2, (4) transparency (haze) and (5) optical film thickness (d) were measured. On the other hand, for the optical film of Comparative Example 2, (6) measurement of birefringence and retardation was attempted, but measurement was not possible due to white turbidity due to aggregation of inorganic particles.

  The results are shown in Table 2.

  As can be seen from the evaluation of transparency in Table 2, the optical films of Comparative Examples 2 to 4 are all unsuitable for optical films because the haze exceeds 3%.

  Moreover, the relationship of the birefringence of the in-plane direction and thickness direction of the optical film of Examples 1-5 and Comparative Examples 1, 3, and 4 is shown in FIG.

  As can be seen from FIG. 1, in the optical films of Examples 1 to 5, the birefringence (ΔNxz + ΔNyz) / 2 in the thickness direction is reduced as compared with the optical film of Comparative Example 1.

In addition, it turns out that the birefringence ((DELTA) Nxy) of the in-plane direction of the optical film of Examples 1-5 and Comparative Example 1 is as low as 200 * 10 < ^-6 > or less.

Claims (2)

An optical film formed from a particle-dispersed resin composition comprising a highly oriented resin and organic-inorganic composite particles having an organic group on the surface of inorganic particles,
The organic-inorganic composite particles have an average maximum length of less than 350 nm and are dispersed as primary particles in the highly oriented resin.
The organic-inorganic composite particle is a high-temperature treatment of the inorganic particle and an organic compound containing the organic group for introducing the organic group on the surface of the inorganic particle at a heating temperature of 100 to 500 ° C. Obtained by
Birefringence (ΔNxz + ΔNyz) / 2 in the thickness direction of the optical film is 12 × 10 ⁻³ or less,
The optical film, wherein birefringence ΔNxy in the in-plane direction orthogonal to the thickness direction of the optical film is 200 × 10 ⁻⁶ or less. A step of preparing organic-inorganic composite particles containing an organic group on the surface of the inorganic particles and having an average maximum length of less than 350 nm,
A step of dispersing the organic-inorganic composite particles as primary particles in a highly oriented resin to prepare a particle-dispersed resin composition; and
Comprising a step of molding an optical film from the particle-dispersed resin composition,
In the step of preparing the organic-inorganic composite particles, the inorganic particles and an organic compound containing the organic groups for introducing the organic groups onto the surfaces of the inorganic particles are heated at a heating temperature of 100 to 500 ° C. High temperature treatment,
Birefringence (ΔNxz + ΔNyz) / 2 in the thickness direction of the optical film is 12 × 10 ⁻³ or less,
The method for producing an optical film, wherein birefringence ΔNxy in an in-plane direction orthogonal to the thickness direction of the optical film is 200 × 10 ⁻⁶ or less.

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