Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L33/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides or nitriles thereof; Compositions of derivatives of such polymers
  • C08L33/04—Homopolymers or copolymers of esters
  • C08L33/06—Homopolymers or copolymers of esters of esters containing only carbon, hydrogen and oxygen, which oxygen atoms are present only as part of the carboxyl radical
  • C08L33/08—Homopolymers or copolymers of acrylic acid esters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/08—Cellulose derivatives
  • C08L1/10—Esters of organic acids, i.e. acylates
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/08—Cellulose derivatives
  • C08L1/10—Esters of organic acids, i.e. acylates
  • C08L1/14—Mixed esters, e.g. cellulose acetate-butyrate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/005—Stabilisers against oxidation, heat, light, ozone
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/08—Cellulose derivatives
  • C08L1/16—Esters of inorganic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L1/00—Compositions of cellulose, modified cellulose or cellulose derivatives
  • C08L1/08—Cellulose derivatives
  • C08L1/20—Esters of both organic acids and inorganic acids
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/30—Polarising elements

Definitions

• the present invention relates to an optical film, and more particularly to an optical film that is transparent, highly heat resistant, and significantly improved in brittleness by blending a specific acrylic resin, a cellulose ester resin, and a specific stabilizer.
• a liquid crystal display device that retains excellent image display properties over a long period of time even when used in harsh environments.
• a liquid crystal display device is composed of a liquid crystal cell in which a transparent electrode, a liquid crystal layer, a color filter, etc. are sandwiched between glass plates, and two polarizing plates provided on both sides thereof.
• the optical element polarizing plate protective film
• a child also referred to as a polarizing film or a polarizing film.
• a cellulose triacetate film is usually used as this polarizing plate protective film.
• PMMA polymethyl methacrylate
• liquid crystal display device As the liquid crystal display device is enlarged as described above, and the applications to the outdoors are expanded, it is necessary to increase the amount of light of the backlight so that the image can be fully recognized even outdoors. It was used under harsh conditions, and heat resistance at high temperatures and longer-term heat resistance were required.
• the PMMA film has poor heat resistance and has a problem that its shape changes when used at high temperatures or for long-term use.
• This problem was an important issue not only as a physical property of a single film but also in a polarizing plate and a display device using such a film. That is, in the liquid crystal display device, the polarizing plate curls as the film is deformed, causing a problem that the entire panel is warped.
• the problem due to film deformation is also a problem on the backlight side, but when used at the position on the viewing side surface, the design phase difference changes due to deformation, so the viewing angle changes and the color changes. The problem arises.
• the acrylic resin film is fragile and brittle when compared with a cellulose ester film and the like, and is difficult to handle. In particular, it is difficult to stably produce an optical film for a large liquid crystal display device. It was.
• Patent Document 1 a resin in which an acrylic resin is combined with an impact-resistant acrylic rubber-methyl methacrylate copolymer or butyl-modified acetyl cellulose has been proposed.
• Patent Document 2 A technique has also been proposed in which a relatively low molecular weight acrylic resin is mixed with a conventional cellulose ester film to control a plasticizer and optical properties (Patent Document 2).
• the acrylic resin is not added to such an extent that the moisture resistance can be sufficiently improved, so that sufficient moisture resistance cannot be obtained. Problems such as changes in value were not solved.
• Patent Document 3 proposes an optical film obtained by melt-mixing an acrylic resin having a relatively large molecular weight and a cellulose ester resin. This technique is a technique lacking versatility because the compatibility between the acrylic resin and the cellulose ester resin may not be sufficient.
• an object of the present invention is an optical film that is transparent, highly heat resistant, and has markedly improved brittleness by blending a specific acrylic resin and cellulose ester resin, and can be used in a high temperature environment.
• Another object of the present invention is to provide an optical film that retains excellent image display properties over the long term, and a liquid crystal display device using the optical film.
• the acrylic resin (A) and the cellulose ester resin (B) are contained in a mass ratio of 95: 5 to 50:50, and the weight average molecular weight Mw of the acrylic resin (A) is 110,000 to 1000000, and the cellulose ester Resin having total substitution degree (T) of acyl group of resin (B) of 2.0 or more and 3.0 or less, substitution degree of acyl group of 3 or more and 7 or less carbon atoms of 1.2 or more and 3.0 or less
• An optical film comprising a composition and comprising a stabilizer (D).
• the optical film has low hygroscopicity, is transparent, has high heat resistance, and has markedly improved brittleness.
• the “optical film” is a functional film used for various display devices such as a liquid crystal display, a plasma display, and an organic EL display, and more specifically, a polarizing plate protective film and a retardation film for a liquid crystal display device. , An antireflection film, a brightness enhancement film, a hard coat film, an antiglare film, an antistatic film, an optical compensation film for expanding the viewing angle, and the like.
• the optical film of the present invention is preferably used for a polarizing plate protective film (including a polarizing plate protective film provided with a functional layer) and a retardation film.
• the optical film of the present invention contains the acrylic resin (A) and the cellulose ester resin (B) in a mass ratio of 95: 5 to 50:50, and the weight average molecular weight Mw of the acrylic resin (A) is 110,000 or more and 1000000.
• the total substitution degree (T) of the acyl group of the cellulose ester resin (B) is 2.0 or more and 3.0 or less, and the substitution degree of the acyl group having 3 or more and 7 or less carbon atoms is 1.2 or more.
• An optical film comprising a resin composition of 3.0 or less and containing a stabilizer (D). In some cases, adding acrylic particles (C) produces favorable results.
• the acrylic resin used in the present invention includes a methacrylic resin.
• the resin is not particularly limited, but a resin comprising 50 to 99% by mass of methyl methacrylate units and 1 to 50% by mass of other monomer units copolymerizable therewith is preferable.
• Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 alkyl carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, alkyl acrylates such as acrylic acid and methacrylic acid.
• Unsaturated group-containing divalent carboxylic acids such as saturated acid, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and ⁇ -methylstyrene, ⁇ , ⁇ -unsaturated nitriles such as acrylonitrile and methacrylonitrile, Examples thereof include maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride and the like, and these can be used alone or in combination of two or more monomers.
• methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer.
• n-Butyl acrylate is particularly preferably used.
• the acrylic resin (A) used in the optical film of the present invention has a weight average molecular weight (Mw) particularly from the viewpoint of improving brittleness as an optical film and improving transparency when it is compatible with the cellulose ester resin (B). Is 110,000 or more and 1000000 or less.
• the weight average molecular weight (Mw) of the acrylic resin (A) is less than 110000, sufficient brittleness improvement may not be obtained, and the compatibility with the cellulose ester resin (B) is likely to deteriorate.
• the weight average molecular weight (Mw) of the acrylic resin (A) is more preferably in the range of 110000 to 600000, and particularly preferably in the range of 110000 to 400000.
• the production method of the acrylic resin (A) in the present invention is not particularly limited, and any known method such as suspension polymerization, emulsion polymerization, bulk polymerization, or solution polymerization may be used.
• a polymerization initiator a normal peroxide type and an azo type can be used, and a redox type can also be used.
• the polymerization temperature may be 30 to 100 ° C. for suspension or emulsion polymerization, and 80 to 160 ° C. for bulk or solution polymerization.
• polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent.
• the cellulose ester resin (B) of the present invention has a total acyl group substitution degree (T) of 2.0 to 3.3 from the viewpoint of transparency particularly when it is improved in brittleness and is compatible with the acrylic resin (A).
• the substitution degree of the acyl group having 0 and 3 to 7 carbon atoms is 1.2 to 3.0. That is, the cellulose ester resin of the present invention is a cellulose ester resin substituted with an acyl group having 3 to 7 carbon atoms.
• propionyl, butyryl and the like are preferably used, but a propionyl group is particularly preferably used. .
• the acrylic ester When the total substitution degree of the acyl group of the cellulose ester resin (B) is less than 2.0, that is, when the residual degree of the hydroxyl groups at the 2, 3, and 6 positions of the cellulose ester molecule is more than 1.0, the acrylic ester When the resin (A) and the cellulose ester resin (B) are not sufficiently compatible and used as an optical film, haze may be a problem.
• the substitution degree of the acyl group having 3 to 7 carbon atoms is less than 1.2, still sufficient compatibility cannot be obtained, Brittleness may be reduced.
• the substitution degree of the acyl group having 2 carbon atoms, that is, the acetyl group is high, and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1. If it is less than 2, the compatibility may decrease and haze may increase.
• the total substitution degree (T) is 2.0 to 3.0, and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1.2 to 3.
• the total substitution degree of acyl groups other than 3 to 7 carbon atoms, that is, acetyl groups or acyl groups having 8 or more carbon atoms, is preferably 1.3 or less.
• the total substitution degree (T) of the acyl group of the cellulose ester resin (B) is more preferably in the range of 2.5 to 3.0.
• the acyl group may be an aliphatic acyl group or an aromatic acyl group. In the case of an aliphatic acyl group, it may be linear or branched and may further have a substituent.
• the number of carbon atoms of the acyl group in the present invention includes an acyl group substituent.
• the number of substituents X substituted on the aromatic ring is preferably 0 to 5. Also in this case, it is necessary to pay attention so that the degree of substitution of the acyl group having 3 to 7 carbon atoms including the substituent is 1.2 to 3.0.
• the benzoyl group has 7 carbon atoms, when it has a substituent containing carbon, the benzoyl group has 8 or more carbon atoms and is not included in the acyl group having 3 to 7 carbon atoms. Become.
• substituents substituted on the aromatic ring when the number of substituents substituted on the aromatic ring is 2 or more, they may be the same or different from each other, but they may be linked together to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, quinoline). , Isoquinoline, chromene, chroman, phthalazine, acridine, indole, indoline, etc.).
• a condensed polycyclic compound for example, naphthalene, indene, indane, phenanthrene, quinoline.
• Isoquinoline chromene, chroman, phthalazine, acridine, indole, indoline, etc.
• a structure having at least one kind of an aliphatic acyl group having 3 to 7 carbon atoms is used as a structure used in the cellulose ester resin (B) of the present invention.
• the cellulose ester resin (B) according to the present invention is preferably at least one selected from cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, and cellulose butyrate.
• cellulose ester resins that are particularly preferred are cellulose acetate propionate and cellulose propionate.
• the portion not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods.
• substitution degree of the acetyl group and the substitution degree of other acyl groups were determined by the method prescribed in ASTM-D817-96.
• the weight average molecular weight (Mw) of the cellulose ester resin (B) according to the present invention is preferably in the range of 75,000 to 300,000, particularly from the viewpoint of improvement in compatibility with the acrylic resin (A) and brittleness, and 100,000 to 250,000. Is more preferably in the range of 150,000 to 250,000.
• the important average molecular weight (Mw) of the cellulose ester resin is less than 75,000, the effect of improving heat resistance and brittleness may not be sufficient, and the effect of the present invention may not be obtained.
• Mw important average molecular weight
• two or more kinds of cellulose resins can be mixed and used.
• the acrylic resin (A) and the cellulose ester resin (B) are contained at a mass ratio of 95: 5 to 50:50 and in a compatible state, preferably 90:10 to 60. : 40.
• the mass ratio of the acrylic resin (A) and the cellulose ester resin (B) is more than 95: 5, the effect of the cellulose ester resin (B) cannot be sufficiently obtained, and the mass ratio is When the acrylic resin is less than 50:50, the moisture resistance is insufficient.
• the acrylic resin (A) and the cellulose ester resin (B) must be contained in a compatible state.
• the physical properties and quality required for an optical film are achieved by supplementing each other by dissolving different resins.
• Whether the acrylic resin (A) and the cellulose ester resin (B) are in a compatible state can be determined by, for example, the glass transition temperature Tg.
• the two resins have different glass transition temperatures
• there are two or more glass transition temperatures for each resin because there is a glass transition temperature for each resin.
• the glass transition temperature specific to each resin disappears and becomes one glass transition temperature, which is the glass transition temperature of the compatible resin.
• the glass transition temperature referred to here is an intermediate value determined according to JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer) at a heating rate of 20 ° C./min.
• the point glass transition temperature (Tmg) is an intermediate value determined according to JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer) at a heating rate of 20 ° C./min.
• the point glass transition temperature (Tmg) The point glass transition temperature (Tmg).
• the acrylic resin (A) and the cellulose ester resin (B) are each preferably an amorphous resin, and either one may be a crystalline polymer or a partially crystalline polymer. In the present invention, the acrylic resin (A) and the cellulose ester resin (B) are preferably compatible with each other to become an amorphous resin.
• the weight average molecular weight (Mw) of the acrylic resin (A), the weight average molecular weight (Mw) of the cellulose ester resin (B), and the degree of substitution are different in solubility in the solvent of both resins. It is obtained by measuring each after use. When fractionating the resin, it is possible to extract and separate the soluble resin by adding a compatible resin in a solvent that is soluble only in either one. At this time, heating operation or reflux is performed. May be. A combination of these solvents may be combined in two or more steps to separate the resin.
• the dissolved resin and the resin remaining as an insoluble material are filtered off, and the solution containing the extract can be separated by an operation of evaporating the solvent and drying.
• These fractionated resins can be identified by general structural analysis of polymers.
• the optical film of the present invention contains a resin other than the acrylic resin (A) and the cellulose ester resin (B), it can be separated by the same method.
• the weight average molecular weights (Mw) of the compatible resins are different, the high molecular weight substances are eluted earlier by gel permeation chromatography (GPC), and the lower molecular weight substances are eluted after a longer time. Therefore, it can be easily fractionated and the molecular weight can be measured.
• GPC gel permeation chromatography
• the molecular weight of the compatible resin is measured by GPC, and at the same time, the resin solution eluted every time is separated, the solvent is distilled off, and the dried resin is different by quantitatively analyzing the structure.
• the resin composition for each molecular weight fraction it is possible to identify each compatible resin.
• the molecular weight distribution of each of the resins separated in advance based on the difference in solubility in a solvent by GPC, it is possible to detect each of the compatible resins.
• containing acrylic resin (A) and cellulose ester resin (B) in a compatible state means mixing each resin (polymer), resulting in a compatible state. This means that a state in which a precursor of acrylic resin such as monomer, dimer or oligomer is mixed with cellulose ester resin (B) and then polymerized by polymerization is not included. .
• the process of obtaining a mixed resin by mixing a precursor of an acrylic resin such as a monomer, dimer or oligomer with the cellulose ester resin (B) and then polymerizing it is complicated by the polymerization reaction.
• the resin is difficult to control the reaction, and it is difficult to adjust the molecular weight.
• graft polymerization, cross-linking reaction or cyclization reaction often occurs.
• the resin is soluble in a solvent or cannot be melted by heating. Since it is difficult to elute the resin and measure the weight average molecular weight (Mw), it is difficult to control the physical properties and it cannot be used as a resin for stably producing an optical film.
• Mw weight average molecular weight
• the total mass of the acrylic resin (A) and the cellulose ester resin (B) in the optical film of the present invention is preferably 55% by mass or more of the optical film, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.
• a hindered amine compound (HALS) is exemplified as the stabilizer (D) used for stabilizing the compatibility of the acrylic resin (A) and the cellulose ester resin (B) over time.
• HALS hindered amine compound
• R1 and R2 are H or a substituent.
• hindered amine compounds include 4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-allyl-4-hydroxy-2,2,6,6-tetramethylpiperidine, 1-benzyl-4 -Hydroxy-2,2,6,6-tetramethylpiperidine, 1- (4-tert-butyl-2-butenyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, 4-stearoyloxy- 2,2,6,6-tetramethylpiperidine, 1-ethyl-4-salicyloyloxy-2,2,6,6-tetramethylpiperidine, 4-methacryloyloxy-1,2,2,6,6- Pentamethylpiperidine, 1,2,2,6,6-pentamethylpiperidin-4-yl- ⁇ (3,5-di-t-butyl-4-hydroxyphenyl) -propionate, 1- Benzyl-2,2,6,6-tetramethyl-4-piperidinyl maleate, (di-2,2,6,6
• At least one or more stabilizers in the cellulose ester of the present invention can be selected, and the amount to be added is 0.001% by mass to 5% by mass with respect to the mass of the cellulose ester. More preferably, it is 0.005 mass% or more and 3 mass% or less, More preferably, it is 0.01 mass% or more and 0.8 mass% or less.
• the above-mentioned hindered amine compound is preferably, for example, commercially available from Ciba Japan Co., Ltd. under the trade name “Tinvin 144” and “Tinvin 770”, “Tinuvin 111 FDL”, and from Adeka Co., Ltd. as “ADK STAB LA-52”.
• the optical film of the present invention preferably contains acrylic particles (C).
• the acrylic particles (C) according to the present invention are present in the state of particles (also referred to as incompatible state) in the optical film containing the acrylic resin (A) and the cellulose ester resin (B) in a compatible state. Represents an acrylic component.
• the acrylic particles (C) are obtained, for example, by collecting a predetermined amount of the produced optical film, dissolving it in a solvent, stirring, and sufficiently dissolving / dispersing it, so that the pore diameter is less than the average particle diameter of the acrylic particles (C). It is preferable that the weight of the insoluble matter filtered and collected using the PTFE membrane filter is 90% by mass or more of the acrylic particles (C) added to the optical film.
• the acrylic particles (C) used in the present invention are not particularly limited, but are preferably acrylic particles (C) having a layer structure of two or more layers, particularly the following multilayer structure acrylic granular composite. It is preferable.
• the multilayer structure acrylic granular composite is formed by laminating an innermost hard layer polymer, a cross-linked soft layer polymer exhibiting rubber elasticity, and an outermost hard layer polymer from the center to the outer periphery.
• the multi-layer structure acrylic granular composite is a multi-layer structure acrylic granular composite composed of an innermost hard layer, a crosslinked soft layer, and an outermost hard layer from the center to the outer periphery.
• This three-layer core-shell multilayer acrylic granular composite is preferably used.
• Preferred embodiments of the multilayer structure acrylic granular composite used in the acrylic resin composition according to the present invention include the following.
• Outermost obtained by polymerizing The layered polymer has a three-layer structure, and the obtained three-layered polymer is the innermost hard layer polymer (a) 5 to 40% by mass, the soft layer polymer (b) 30 to 60% by mass.
• an outermost hard layer polymer (c) having an insoluble part when fractionated with acetone, and having a methyl ethyl ketone swelling degree of 1.5 to 4.0. Complex.
• the innermost hard layer polymer (a) constituting the multilayer structure acrylic granular composite is 80 to 98.9% by mass of methyl methacrylate and 1 to 20 mass of alkyl acrylate having 1 to 8 carbon atoms in the alkyl group. % And a mixture of monomers consisting of 0.01 to 0.3% by weight of a polyfunctional grafting agent is preferred.
• examples of the alkyl acrylate having 1 to 8 carbon atoms in the alkyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like. And n-butyl acrylate are preferably used.
• the proportion of the alkyl acrylate unit in the innermost hard layer polymer (a) is 1 to 20% by mass.
• the thermal decomposability of the polymer is increased, while the unit is 20% by mass. If it exceeds 50%, the glass transition temperature of the innermost hard layer polymer (c) is lowered, and the impact resistance imparting effect of the three-layer structure acrylic granular composite is lowered.
• polyfunctional grafting agent examples include polyfunctional monomers having different polymerizable functional groups, such as allyl esters of acrylic acid, methacrylic acid, maleic acid, and fumaric acid, and allyl methacrylate is preferably used.
• the polyfunctional grafting agent is used to chemically bond the innermost hard layer polymer and the soft layer polymer, and the ratio used during the innermost hard layer polymerization is 0.01 to 0.3% by mass. .
• the crosslinked soft layer polymer (b) constituting the acrylic granular composite is an alkyl acrylate having from 9 to 8 carbon atoms having an alkyl group of 1 to 8 in the presence of the innermost hard layer polymer (a). What is obtained by polymerizing a mixture of monomers comprising, by mass, 0.01 to 5% by mass of a polyfunctional crosslinking agent and 0.5 to 5% by mass of a polyfunctional grafting agent is preferred.
• n-butyl acrylate or 2-ethylhexyl acrylate is preferably used as the alkyl acrylate having 4 to 8 carbon atoms in the alkyl group.
• Examples of other monofunctional monomers that can be copolymerized include styrene and substituted styrene derivatives.
• styrene and substituted styrene derivatives Regarding the ratio of alkyl acrylate having 4 to 8 carbon atoms in the alkyl group and styrene, the more the former, the lower the glass transition temperature of the polymer (b), that is, the softer it is.
• the refractive index of the soft layer polymer (b) at room temperature is set to the innermost hard layer polymer (a), the outermost hard layer polymer (c), and the hard heat. It is more advantageous to make it closer to the plastic acrylic resin, and the ratio between them is selected in consideration of these.
• polyfunctional grafting agent those mentioned in the section of the innermost layer hard polymer (a) can be used.
• the polyfunctional grafting agent used here is used to chemically bond the soft layer polymer (b) and the outermost hard layer polymer (c), and the proportion used during the innermost hard layer polymerization is impact resistance. From the viewpoint of the effect of imparting properties, 0.5 to 5% by mass is preferable.
• polyfunctional crosslinking agent generally known crosslinking agents such as divinyl compounds, diallyl compounds, diacrylic compounds, dimethacrylic compounds and the like can be used, but polyethylene glycol diacrylate (molecular weight 200 to 600) is preferably used.
• the polyfunctional cross-linking agent used here is used to generate a cross-linked structure during the polymerization of the soft layer (b) and to exhibit the effect of imparting impact resistance.
• the polyfunctional crosslinking agent is not an essential component because the crosslinked structure of the soft layer (b) is generated to some extent. Is preferably 0.01 to 5% by weight from the viewpoint of imparting impact resistance.
• the outermost hard layer polymer (c) constituting the multi-layer structure acrylic granular composite has a methyl methacrylate of 80 to 99 mass in the presence of the innermost hard layer polymer (a) and the soft layer polymer (b). % And a mixture of monomers consisting of 1 to 20% by mass of an alkyl acrylate having 1 to 8 carbon atoms in the alkyl group is preferred.
• the acrylic alkylate those described above are used, but methyl acrylate and ethyl acrylate are preferably used.
• the proportion of the alkyl acrylate unit in the outermost hard layer (c) is preferably 1 to 20% by mass.
• an alkyl mercaptan or the like can be used as a chain transfer agent to adjust the molecular weight for the purpose of improving the compatibility with the acrylic resin (A).
• the outermost hard layer with a gradient such that the molecular weight gradually decreases from the inside toward the outside in order to improve the balance between elongation and impact resistance.
• the outermost hard layer is divided into two or more monomer mixtures for forming the outermost hard layer, and the amount of chain transfer agent to be added each time is increased sequentially. It is possible to decrease the molecular weight of the polymer forming the layer from the inside to the outside of the multilayer structure acrylic granular composite.
• the particle diameter of the acrylic particles (C) preferably used in the present invention is not particularly limited, but is preferably 10 nm or more and 1000 nm or less, and more preferably 20 nm or more and 500 nm or less. In particular, the thickness is most preferably from 50 nm to 400 nm.
• the mass ratio of the core and the shell is not particularly limited, but when the entire multilayer structure polymer is 100 parts by mass,
• the core layer is preferably 50 parts by mass or more and 90 parts by mass or less, and more preferably 60 parts by mass or more and 80 parts by mass or less.
• the core layer here is an innermost hard layer.
• acrylic particles (C) which are graft copolymers suitably used as the acrylic particles (C) preferably used in the present invention include unsaturated carboxylic acid ester-based monomers in the presence of a rubbery polymer.
• unsaturated carboxylic acid ester-based monomers in the presence of a rubbery polymer.
• a mixture of a monomer, an unsaturated carboxylic acid monomer, an aromatic vinyl monomer, and, if necessary, other vinyl monomers copolymerizable therewith were copolymerized.
• a graft copolymer is mentioned.
• the rubbery polymer used for the acrylic particle (C) which is a graft copolymer Diene type rubber, acrylic type rubber, ethylene type rubber, etc.
• Specific examples include polybutadiene, styrene-butadiene copolymer, block copolymer of styrene-butadiene, acrylonitrile-butadiene copolymer, butyl acrylate-butadiene copolymer, polyisoprene, butadiene-methyl methacrylate copolymer, Butyl acrylate-methyl methacrylate copolymer, butadiene-ethyl acrylate copolymer, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-isoprene copolymer, and ethylene-methyl acrylate copolymer A polymer etc. are mentioned. These rubbery polymers can be used alone or
• the refractive index of the mixture of an acrylic resin (A) and a cellulose-ester resin (B) and the refractive index of an acrylic particle (C) must be near. From the viewpoint of obtaining a film with high transparency.
• the refractive index difference between the acrylic particles (C) and the acrylic resin (A) is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.
• a method of adjusting the monomer unit composition ratio of the acrylic resin (A) and / or a rubbery polymer or monomer used for the acrylic particles (C) The refractive index difference can be reduced by a method of adjusting the composition ratio, and an optical film excellent in transparency can be obtained.
• the refractive index difference referred to here is a solution in which the optical film of the present invention is sufficiently dissolved in an appropriate condition in a solvent in which the acrylic resin (A) is soluble. After separating the solvent-soluble part and the insoluble part and purifying the soluble part (acrylic resin (A)) and insoluble part (acrylic particles (C)), the measured refractive index (23 ° C., measuring wavelength: 550 nm). ) Difference.
• the method of blending the acrylic particles (C) with the acrylic resin (A) is not particularly limited. After the acrylic resin (A) and other optional components are previously blended, usually at 200 to 350 ° C. A method of uniformly melt-kneading with a single-screw or twin-screw extruder while adding acrylic particles (C) is preferably used.
• a method in which a solution in which acrylic particles (C) are dispersed in advance is added to and mixed with a solution (dope solution) in which acrylic resin (A) and cellulose ester resin (B) are dissolved, acrylic particles (C) and A method such as in-line addition of a solution obtained by dissolving or mixing other optional additives can be used.
• Acrylic particles can also be used as the acrylic particles according to the present invention.
• Metabrene W-341 (C1) manufactured by Mitsubishi Rayon Co., Ltd.
• Chemisnow MR-2G (C2) Chemisnow MR-2G (C2)
• MS-300X manufactured by Soken Chemical Co., Ltd.
• Kane Ace manufactured by Kaneka Chemical Co., Ltd.
• Paraloid manufactured by Kureha Chemical Industry Co., Ltd.
• Acryloid manufactured by Rohm and Haas Co., Ltd.
• Staphyloid manufactured by Ganz Kasei Kogyo Co., Ltd.
• Parapet SA manufactured by Kuraray Co., Ltd.
• the optical film of the present invention preferably contains 0.5 to 30% by mass of acrylic particles (C) with respect to the total mass of the resin constituting the film, and is in the range of 1.0 to 15% by mass. It is more preferable to contain.
• the optical film of the present invention includes a plasticizer for imparting processability to the film, an antioxidant for preventing deterioration of the film, an ultraviolet absorber for imparting an ultraviolet absorbing function, and fine particles (matting agent) for imparting slipperiness to the film. It is preferable to contain additives such as
• plasticizer examples include phthalate ester, fatty acid ester, trimellitic ester, phosphate ester, polyester, and epoxy.
• polyester-based and phthalate-based plasticizers are preferably used.
• Polyester plasticizers are superior in non-migration and extraction resistance compared to phthalate ester plasticizers such as dioctyl phthalate, but are slightly inferior in plasticizing effect and compatibility.
• the polyester plasticizer is a reaction product of a monovalent or tetravalent carboxylic acid and a monovalent or hexavalent alcohol, and is mainly obtained by reacting a divalent carboxylic acid with a glycol.
• Representative divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, sebacic acid and the like.
• glycol examples include glycols such as ethylene, propylene, 1,3-butylene, 1,4-butylene, 1,6-hexamethylene, neopentylene, diethylene, triethylene, and dipropylene. These divalent carboxylic acids and glycols may be used alone or in combination.
• the ester plasticizer may be any of ester, oligoester, and polyester types, and the molecular weight is preferably in the range of 100 to 10,000, and preferably in the range of 600 to 3000, which has a large plasticizing effect.
• the viscosity of the plasticizer has a correlation with the molecular structure and molecular weight, but in the case of an adipic acid plasticizer, the range of 200 to 5000 MPa ⁇ s (25 ° C.) is preferable because of compatibility and plasticization efficiency. Furthermore, some polyester plasticizers may be used in combination.
• the plasticizer is preferably added in an amount of 0.5 to 30 parts by mass with respect to 100 parts by mass of the optical film of the present invention. If the added amount of the plasticizer exceeds 30 parts by mass, the surface becomes sticky, which is not preferable for practical use.
• lactone, sulfur, phenol, double bond, and phosphorus compounds can be preferably used.
• the phenolic compound preferably has a 2,6-dialkylphenol structure.
• trade names of Ciba Japan Co., Ltd. “Irganox 1076”, “Irganox 1010”, and ADEKA “ADEKA STAB AO-50” And those commercially available.
• the phosphorous compounds are, for example, from Sumitomo Chemical Co., Ltd., “Sumilizer GP”, ADEKA Co., Ltd., ADK STAB PEP-24G, “ADK STAB PEP-36” and “ADK STAB 3010”, “Ciba Japan Co., Ltd.” IRGAFOS P-EPQ ", commercially available from Sakai Chemical Industry Co., Ltd. under the trade name" GSY-P101 "is preferred.
• the above sulfur compounds are preferably those commercially available from Sumitomo Chemical Co., Ltd. under the trade names “Sumilizer TPL-R” and “Sumilizer TP-D”.
• the above-mentioned double bond compound is preferably commercially available from Sumitomo Chemical Co., Ltd. under the trade names of “Sumilizer GM” and “Sumilizer GS”.
• the amount of these antioxidants and the like to be added is appropriately determined in accordance with the process for recycling and use, but generally 0.05 to 20% by mass, preferably with respect to the resin as the main raw material of the film Is added in the range of 0.1 to 1% by mass.
• antioxidants can obtain a synergistic effect by using several different types of compounds in combination rather than using only one kind.
• the combined use of lactone, phosphorus, phenol and double bond compounds is preferred.
• a colorant means a dye or a pigment.
• the colorant refers to a colorant having an effect of making the color tone of a liquid crystal screen a blue tone, adjusting a yellow index, and reducing haze.
• dyes and pigments can be used as the colorant, but anthraquinone dyes, azo dyes, phthalocyanine pigments and the like are effective.
• UV absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body. It is good also as a polymer type ultraviolet absorber.
• ⁇ Matting agent> it is preferable to add a matting agent in order to impart film slipperiness.
• any inorganic compound or organic compound may be used as long as it has heat resistance at the time of melting without impairing the transparency of the obtained film.
• talc mica, zeolite, diatomaceous earth, Calcined siliceous clay, kaolin, sericite, bentonite, smectite, clay, silica, quartz powder, glass beads, glass powder, glass flakes, milled fiber, wollastonite, boron nitride, boron carbide, titanium boride, magnesium carbonate, Heavy calcium carbonate, light calcium carbonate, calcium silicate, aluminum silicate, magnesium silicate, magnesium aluminosilicate, alumina, silica, zinc oxide, titanium dioxide, iron oxide, magnesium oxide, zirconium oxide, aluminum hydroxide, calcium hydroxide, water Magne oxide Um, calcium sulfate, barium sulfate, silicon carbide, aluminum carbide, titanium carbide, aluminum nitride
• High transparency and slipperiness can be achieved at the same time by using particles having different particle sizes and shapes (for example, needle shape and spherical shape).
• silicon dioxide is particularly preferably used since it has a refractive index close to that of cellulose ester and is excellent in transparency (haze).
• silicon dioxide examples include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (manufactured by Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP- 30, Seahoster KEP-50 (above, manufactured by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (manufactured by Fuji Silysia), Nip Seal E220A (manufactured by Nippon Silica Industry), Admafine SO (manufactured by Admatechs), etc. Goods etc. can be preferably used.
• the shape of the particles can be used without particular limitation, such as indefinite shape, needle shape, flat shape, spherical shape, etc. However, the use of spherical particles is preferable because the transparency of the resulting film can be improved.
• the particle size is preferably smaller than the wavelength of visible light, and more preferably 1 ⁇ 2 or less of the wavelength of visible light. . If the size of the particles is too small, the slipperiness may not be improved, so the range of 80 nm to 180 nm is particularly preferable.
• the particle size means the size of the aggregate when the particle is an aggregate of primary particles. Moreover, when a particle is not spherical, it means the diameter of a circle corresponding to the projected area.
• a hydrogen bonding solvent can be added for the purpose of reducing the melt viscosity.
• the hydrogen bonding solvent is J.I. N.
• the glass transition temperature of the cellulose resin used alone is higher than that.
• the melting temperature of the cellulose resin composition can be lowered by the addition of a hydrogen bonding solvent, or the melt viscosity of the cellulose resin composition containing a hydrogen bonding solvent can be lowered at the same melting temperature as the cellulose resin. .
• the brittleness index is determined based on the criterion of whether or not it is “an optical film that does not cause ductile fracture”.
• the ductile fracture is a fracture that occurs due to a stress that is greater than the strength of a certain material, and is defined as a fracture that involves significant elongation or drawing of the material before the final fracture.
• whether or not it is “an optical film that does not cause ductile fracture” is evaluated based on the fact that no breakage or the like is observed even when a large stress is applied such that the film is folded in two. . (This evaluation is called folding resistance.) Even if it is used as a polarizing plate protective film for a large-sized liquid crystal display device, if it is an optical film that does not cause ductile fracture even when such a large stress is applied, problems such as breakage during production Furthermore, even when the optical film is used after being peeled off after being pasted once, no breakage occurs and the optical film can be sufficiently reduced in thickness.
• the folding resistance is 50 to 100 times, even when used as a polarizing plate protective film for a large-sized liquid crystal display device, it is possible to sufficiently reduce problems such as breakage during manufacturing. Furthermore, even when the optical film is used after being pasted once and then peeled off again, no breakage occurs, and the optical film can be sufficiently reduced in thickness.
• the tension softening point is used as an index of heat resistance.
• the tension softening point is 105 ° C. to 145 ° C., it can be judged that sufficient heat resistance is exhibited.
• the tension softening point is less than 105 ° C., the heat generated by the backlight light source cannot be withstood, and the film is likely to be deformed or light leakage is likely to occur.
• the tension softening point is suitably from 105 ° C to 145 ° C.
• the optical film is cut out at 120 mm (length) ⁇ 10 mm (width).
• the temperature can be raised at a rate of 30 ° C./min while pulling with a tension of 10 N, and the temperature at the time when the pressure reaches 9 N is measured three times, and the average value can be obtained.
• the optical film preferably has a glass transition temperature (Tg) of 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more.
• Tg glass transition temperature
• the glass transition temperature referred to here is an intermediate point determined according to JIS K7121 (1987), measured with a differential scanning calorimeter (DSC-7, manufactured by Perkin Elmer) at a heating rate of 20 ° C. Glass transition temperature (Tmg).
• Haze value is used as an index for judging the transparency of the optical film in the present invention.
• liquid crystal display devices used outdoors are required to have sufficient brightness and high contrast even in a bright place. Therefore, the haze value is required to be 1.0% or less, and 0.5% or less. More preferably.
• the optical film of the present invention containing the acrylic resin (A) and the cellulose ester resin (B), high transparency can be obtained, but when using acrylic particles for the purpose of improving another physical property.
• acrylic particles for the purpose of improving another physical property.
• the particle diameter and addition amount of acrylic particles (C) should be kept within the above range, and the surface roughness of the film contact portion during film formation should be reduced. Is also effective.
• the dimensional change rate (%) under the above conditions is less than 0.5%, it can be evaluated as an optical film exhibiting sufficiently low hygroscopicity. Furthermore, it is preferable that it is less than 0.3%.
• the optical film of the present invention preferably has a defect with a diameter of 5 ⁇ m or more in the film plane of 1 piece / 10 cm square or less. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less.
• the diameter of the defect indicates the diameter when the defect is circular, and when it is not circular, the range of the defect is determined by observing with a microscope according to the following method, and the maximum diameter (diameter of circumscribed circle) is determined.
• the range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object.
• the defect is a change in the surface shape, such as transfer of a roll flaw or an abrasion
• the size is confirmed by observing the defect with the reflected light of a differential interference microscope.
• the film When the number of defects is more than 1/10 cm square, for example, when a tension is applied to the film during processing in a later process, the film may be broken with the defect as a starting point and productivity may be reduced. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.
• the coating agent may not be formed uniformly, resulting in defects (coating defects).
• the defect is a void in the film (foaming defect) generated due to the rapid evaporation of the solvent in the drying process of the solution casting, a foreign matter in the film forming stock solution, or a foreign matter mixed in the film forming. This refers to the foreign matter (foreign matter defect) in the film.
• the optical film of the present invention preferably has a breaking elongation in at least one direction of 10% or more, more preferably 20% or more in the measurement based on JIS-K7127-1999.
• the upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.
• the optical film of the present invention preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%.
• the optical film of the present invention can be particularly preferably used as a polarizing plate protective film for a large-sized liquid crystal display device or a liquid crystal display device for outdoor use as long as the above physical properties are satisfied.
• the usual inflation method, T-die method, calendar method, cutting method, casting method, emulsion method, hot press method and the like can be used. From the viewpoint of suppression of defects and suppression of optical defects such as die line, a solution casting film forming method and a melt casting film forming method by a casting method are preferable.
• Organic solvents useful for forming the dope when the optical film of the present invention is produced by the solution casting method are acrylic resin (A), cellulose ester resin (B), stabilizer (D), and optionally acrylic particles. If (C) and other additives are dissolved simultaneously, it can be used without limitation.
• methylene chloride as a non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, nitroethane, etc.
• Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.
• the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms.
• a linear or branched aliphatic alcohol having 1 to 4 carbon atoms.
• the ratio of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy.
• acrylic resin (A) and cellulose ester in non-chlorine organic solvent system There is also a role of promoting dissolution of the resin (B).
• the dope composition is preferably prepared by dissolving at least 15 to 45 mass% of the four types of acrylic particles (C).
• linear or branched aliphatic alcohol having 1 to 4 carbon atoms examples include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.
• Dissolution Step In an organic solvent mainly composed of a good solvent for the acrylic resin (A) and the cellulose ester resin (B), the acrylic resin (A), the cellulose ester resin (B), and the stabilizer (D) in a dissolution vessel.
• the acrylic particles (C) and other additives are dissolved with stirring to form a dope, or the acrylic resin (A), the cellulose ester resin (B), and the stabilizer (D) solution.
• an acrylic particle (C) solution and other additive solutions are mixed to form a dope that is a main solution.
• a method carried out at normal pressure a method carried out below the boiling point of the main solvent, a method carried out under pressure above the boiling point of the main solvent, JP-A-9-95544
• Various dissolution methods such as a method of performing a cooling dissolution method as described in JP-A-9-95557 or JP-A-9-95538, a method of performing at a high pressure as described in JP-A-11-21379, and the like.
• a method in which pressure is applied at a temperature equal to or higher than the boiling point of the main solvent is particularly preferable.
• the acrylic resin (A) and cellulose ester resin (B) in the dope are preferably in the range of 15 to 45% by mass in total.
• a filter medium having a collected particle diameter of 0.5 to 5 ⁇ m and a drainage time of 10 to 25 sec / 100 ml.
• the aggregate remaining at the time of particle dispersion and the aggregate generated when the main dope is added are aggregated by using a filter medium having a collected particle diameter of 0.5 to 5 ⁇ m and a drainage time of 10 to 25 sec / 100 ml. Can only be removed.
• the concentration of particles is sufficiently thinner than that of the additive solution, so that the aggregates do not stick together during filtration and the filtration pressure does not increase suddenly.
• the main dope may contain about 10 to 50% by weight of recycled material.
• the return material may contain acrylic particles. In that case, it is preferable to control the addition amount of the acrylic particle addition liquid in accordance with the addition amount of the return material.
• the additive liquid containing acrylic particles preferably contains 0.5 to 10% by mass of acrylic particles, more preferably 1 to 10% by mass, and more preferably 1 to 5% by mass. Most preferably.
• the additive solution is preferable because it has a low viscosity and is easy to handle and can be easily added to the main dope.
• the return material is a product obtained by finely pulverizing the optical film, which is generated when the optical film is formed, and is obtained by cutting off both sides of the film, or by using an optical film original that has been speculated out due to scratches, etc. .
• acrylic resin cellulose ester resin, and in some cases, acrylic particles kneaded into pellets can be preferably used.
• An endless metal belt such as a stainless steel belt or a rotating metal drum, which supports the dope is fed to a pressure die through a liquid feed pump (for example, a pressurized metering gear pump) and supported infinitely. This is a step of casting a dope from a pressure die slit to a casting position on the body.
• a liquid feed pump for example, a pressurized metering gear pump
• ⁇ Pressure dies that can adjust the slit shape of the die base and make the film thickness uniform are preferred.
• the pressure die include a coat hanger die and a T die, and any of them is preferably used.
• the surface of the metal support is a mirror surface.
• two or more pressure dies may be provided on the metal support, and the dope amount may be divided and stacked. Or it is also preferable to obtain the film of a laminated structure by the co-casting method which casts several dope simultaneously.
• Solvent evaporation step In this step, the web (the dope is cast on the casting support and the formed dope film is called a web) is heated on the casting support to evaporate the solvent.
• the web on the support after casting is preferably dried on the support in an atmosphere of 40 to 100 ° C. In order to maintain the atmosphere at 40 to 100 ° C., it is preferable to apply hot air at this temperature to the upper surface of the web or heat by means such as infrared rays.
• Peeling process It is the process of peeling the web which the solvent evaporated on the metal support body in a peeling position. The peeled web is sent to the next process.
• the temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.
• the amount of residual solvent at the time of peeling of the web on the metal support at the time of peeling is preferably 50 to 120% by mass depending on the strength of drying conditions, the length of the metal support, and the like. If the web is peeled off at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling will be lost, and slippage and vertical stripes are likely to occur due to the peeling tension. The amount of solvent is determined.
• Residual solvent amount (%) (mass before web heat treatment ⁇ mass after web heat treatment) / (mass after web heat treatment) ⁇ 100 Note that the heat treatment for measuring the residual solvent amount represents performing heat treatment at 115 ° C. for 1 hour.
• the peeling tension at the time of peeling the metal support and the film is usually 196 to 245 N / m. However, if wrinkles easily occur at the time of peeling, it is preferable to peel with a tension of 190 N / m or less. It is preferable to peel at a minimum tension of ⁇ 166.6 N / m, and then peel at a minimum tension of ⁇ 137.2 N / m, and particularly preferable to peel at a minimum tension of ⁇ 100 N / m.
• the temperature at the peeling position on the metal support is preferably ⁇ 50 to 40 ° C., more preferably 10 to 40 ° C., and most preferably 15 to 30 ° C.
• a drying device 35 that alternately conveys the web through a plurality of rolls arranged in the drying device and / or a tenter stretching device 34 that clips and conveys both ends of the web with a clip are used. And dry the web.
• the drying means is generally to blow hot air on both sides of the web, but there is also a means to heat by applying microwaves instead of wind. Too rapid drying tends to impair the flatness of the finished film. Drying at a high temperature is preferably performed from about 8% by mass or less of residual solvent. Throughout, drying is generally performed at 40-250 ° C. In particular, drying at 40 to 160 ° C. is preferable.
• tenter stretching apparatus When using a tenter stretching apparatus, it is preferable to use an apparatus that can independently control the film gripping length (distance from the start of gripping to the end of gripping) left and right by the left and right gripping means of the tenter. In the tenter process, it is also preferable to intentionally create sections having different temperatures in order to improve planarity.
• the stretching operation may be performed in multiple stages, and it is also preferable to perform biaxial stretching in the casting direction and the width direction.
• biaxial stretching When biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise.
• stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible. That is, for example, the following stretching steps are possible.
• Simultaneous biaxial stretching includes stretching in one direction and contracting the other while relaxing the tension.
• the preferred draw ratio for simultaneous biaxial stretching can be in the range of x1.01 to x1.5 in both the width direction and the longitudinal direction.
• the amount of residual solvent in the web is preferably 20 to 100% by mass at the start of the tenter, and drying is preferably performed while the tenter is applied until the amount of residual solvent in the web is 10% by mass or less. More preferably, it is 5% by mass or less.
• the drying temperature is preferably 30 to 160 ° C., more preferably 50 to 150 ° C., and most preferably 70 to 140 ° C.
• the temperature distribution in the width direction of the atmosphere is small from the viewpoint of improving the uniformity of the film.
• the temperature distribution in the width direction in the tenter process is preferably within ⁇ 5 ° C, and within ⁇ 2 ° C. Is more preferable, and within ⁇ 1 ° C. is most preferable.
• Winding step This is a step of winding the optical film by the winder 37 after the residual solvent amount in the web is 2% by mass or less, and the dimensional stability is achieved by setting the residual solvent amount to 0.4% by mass or less. A film having good properties can be obtained. It is particularly preferable to wind up at 0.00 to 0.10% by mass.
• a generally used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc., and these may be used properly.
• the optical film of the present invention is preferably a long film.
• the optical film has a thickness of about 100 m to 5000 m, and is usually in the form of a roll.
• the film width is preferably 1.3 to 4 m, more preferably 1.4 to 2 m.
• the film thickness of the optical film of the present invention is not particularly limited, but when used for a polarizing plate protective film, it is preferably 20 to 200 ⁇ m, more preferably 25 to 100 ⁇ m, and more preferably 30 to 80 ⁇ m. Particularly preferred.
• the optical film of the present invention may be used, or another polarizing plate protective film may be used.
• a commercially available cellulose ester film for example, Konica Minoltack KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KC4FR-4, KC4FR-3, KC4FR-3, KC4FR-4 -1, KC8UY-HA, KC8UX-RHA, manufactured by Konica Minolta Opto Co., Ltd.) and the like are preferably used.
• a polarizer which is a main component of a polarizing plate, is an element that transmits only light having a plane of polarization in a certain direction.
• a typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed.
• urethane adhesives examples include, for example, urethane adhesives, epoxy adhesives, aqueous polymer-isocyanate adhesives, curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types
• curable adhesives such as thermosetting acrylic adhesives, moisture-curing urethane adhesives, polyether methacrylate types
• anaerobic pressure-sensitive adhesives such as ester-based methacrylate type and oxidized polyether methacrylate, cyanoacrylate-based instantaneous pressure-sensitive adhesives, and acrylate-peroxide-based two-component instantaneous pressure-sensitive adhesives.
• the above-mentioned pressure-sensitive adhesive may be a one-component type or a type in which two or more components are mixed before use.
• the above-mentioned pressure-sensitive adhesive may be a solvent system using an organic solvent as a medium, or an aqueous system such as an emulsion type, a colloidal dispersion type, or an aqueous solution type that is a medium containing water as a main component. It may be a solvent type.
• concentration of the pressure-sensitive adhesive liquid may be appropriately determined depending on the film thickness after adhesion, the coating method, the coating conditions, and the like, and is usually 0.1 to 50% by mass.
• polarizing plate bonded with the optical film of the present invention into a liquid crystal display device, it is possible to produce various liquid crystal display devices with excellent visibility, but particularly outdoors such as large liquid crystal display devices and digital signage. It is preferably used for a liquid crystal display device for use.
• the polarizing plate according to the present invention is bonded to a liquid crystal cell via the adhesive layer or the like.
• Example 1 [Preparation of acrylic resin] The following acrylic resins A1-A7 and MS1,2 were prepared by known methods.
• the following commercially available acrylic resins were used.
• the produced dope liquid was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the film was peeled off from the stainless steel band support with a peeling tension of 162 N / m.
• the solvent was evaporated from the peeled acrylic resin web at 35 ° C., slit to 1.6 m width, and then dried at a drying temperature of 135 ° C. while stretching 1.1 times in the width direction with a tenter. At this time, the residual solvent amount when starting stretching with a tenter was 10%.
• the draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times.
• the residual solvent amount of the optical film 1 shown in Table 1 was 0.1%, the film thickness was 60 ⁇ m, and the winding length was 4000 m.
• optical films 2 to 20 were similarly prepared except that the types and composition ratios of the acrylic resin (A), the cellulose ester resin (B), and the stabilizer were changed as shown in Table 1. Was made.
• optical film 21 was manufactured in the same manner as the optical film 1 using the following dope.
• a 120- ⁇ m-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to produce a polarizer.
• the polarizing plate using the optical film of the present invention was excellent in film cutting property and easy to process.
• the viewing angle of the liquid crystal display device was measured using EZ-Contrast 160D manufactured by ELDIM in an environment of 23 ° C. and 55% RH. Subsequently, a sample obtained by treating the polarizing plate at 80 ° C. and 90% RH for 1000 hours was measured in the same manner, and evaluated according to the following criteria.
• the present invention is an optical film that is transparent, has high heat resistance, and has markedly improved brittleness. Further, even when used in a high temperature environment, the image display is excellent over the long term. It can be seen that this is an optical film that retains the properties and a liquid crystal display device using the optical film.

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