JP5771418B2 - Method for producing retardation film having easy adhesion layer - Google Patents

Description

  The present invention relates to a method for producing a retardation film having an easy adhesion layer. Moreover, this invention relates to the phase difference film roll by which the phase difference film which has an easily bonding layer was wound by the roll.

  A retardation film is incorporated in an image display device such as a liquid crystal display device (LCD) for the purpose of color tone compensation and viewing angle compensation. The retardation film is generally formed by stretching a resin film. By stretching the resin film, the polymer contained in the film is oriented, birefringence occurs, and a retardation is developed.

  Patent Document 1 discloses a retardation film composed of an acrylic resin whose main component is a (meth) acrylic polymer having a ring structure in the main chain. This retardation film exhibits excellent optical properties and mechanical properties derived from an acrylic resin. Moreover, it has high heat resistance by using as a main component a (meth) acrylic polymer having a ring structure in the main chain.

  Patent Document 2 describes that an easy-adhesion layer that improves the adhesion between the retardation film and another layer may be provided on the surface of the retardation film. The retardation film may be used by being bonded to another optical film for the purpose of controlling optical characteristics. By providing the easy-adhesion layer, it is expected that the retardation film can be easily and reliably bonded.

Japanese Patent Laid-Open No. 2008-9378 JP 2009-51950 A

  In providing an easy-adhesion layer on the retardation film, it is important that the retardation exhibited by the retardation film is not reduced by the easy-adhesion layer. Patent Document 2 describes that an easy-adhesion layer may be provided on the surface of the retardation film, but a specific method for forming the easy-adhesion layer so that the retardation exhibited by the retardation film is not reduced. Is not listed.

  The present invention is a method for producing a retardation film having an easy-adhesion layer, and provides a method capable of forming an easy-adhesion layer having good adhesion without reducing the retardation exhibited by the retardation film itself. And

  By the way, when the formed retardation film is wound around a roll to form a roll-like retardation film (retardation film roll), blocking may occur. Blocking is particularly likely to occur when the retardation film has an easy adhesion layer. The present invention is a retardation film roll wound with a retardation film having an easy-adhesion layer having good adhesion formed on its surface, and providing a retardation film roll in which occurrence of blocking is suppressed, In addition to the purpose.

  The production method of the present invention is a method for producing a retardation film having an easy-adhesion layer, wherein a urethane resin dispersion is applied to the surface of an acrylic resin film to form a coating film of the dispersion, and the application The acrylic resin film on which the film is formed is stretched under a heating atmosphere, and the retardation film is formed by stretching the acrylic resin film, and the surface of the retardation film is formed by heat treatment of the coating film with the heat of the heating atmosphere. And forming an easy-adhesion layer containing the urethane resin.

  In the retardation film roll of the present invention, a retardation film on which an easy-adhesion layer including a urethane resin and fine particles having an average primary particle diameter exceeding 200 nm is formed is wound, and the wound retardation film is wound. The length in the longitudinal direction of the film is 3000 m or more.

  In the production method of the present invention, the acrylic resin film is stretched. Thereby, the polymer contained in the film is oriented to form a retardation film. Here, the stretching is performed in a heated atmosphere with a urethane resin dispersion applied to the surface of the acrylic resin film and a coating film of the dispersion formed on the surface. The coating film comprised of the urethane resin dispersion changes into an easy-adhesion layer containing the urethane resin by the heat of the heating atmosphere as the acrylic resin film is stretched. The easy-adhesion layer formed in this way does not reduce the retardation exhibited by the retardation film itself formed by stretching the acrylic resin film. That is, an easy-adhesion layer is formed by the manufacturing method of this invention, without reducing the phase difference which retardation film itself shows.

  Conventionally, in order to form an easy-adhesion layer having good adhesion, it has been necessary to previously increase the surface tension of the surface on which the easy-adhesion layer in the resin film is formed by surface treatment such as corona discharge treatment. . In the production method of the present invention, an easy-adhesion layer having good adhesion is formed without subjecting the surface of the acrylic resin film on which the easy-adhesion layer is formed in advance.

  The production method of the present invention is particularly effective when industrially mass-producing a retardation film having an easy-adhesion layer. When mass-producing a retardation film, stretching conditions are generally determined so that a retardation film exhibiting a predetermined retardation is obtained with respect to the resin film before stretching. In the production method of the present invention, an easy-adhesion layer is formed without reducing the retardation exhibited by the retardation film itself. Therefore, the retardation film having an easy-adhesion layer is prepared according to the conditions determined without forming the easy-adhesion layer. Can be manufactured.

  In the retardation film roll of the present invention, the occurrence of blocking is suppressed.

  Unless otherwise specified, “resin” in this specification is a broader concept than “polymer”. The resin may be composed of, for example, one type or two or more types of polymers, and if necessary, materials other than the polymer, for example, additives such as ultraviolet absorbers, antioxidants, fillers, and compatibilizing agents. Further, it may contain a stabilizer and the like.

[Acrylic resin film]
The acrylic resin film is a film composed of an acrylic resin containing a (meth) acrylic polymer as a main component. The content of the (meth) acrylic polymer in the acrylic resin is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, and particularly preferably 95% by weight or more. The (meth) acrylic polymer has excellent optical properties such as high light transmittance and low wavelength dependency of refractive index, and is suitable for use in a retardation film.

  The (meth) acrylic polymer is not limited, and is a polymer having a structural unit ((meth) acrylic acid ester unit) derived from a (meth) acrylic acid ester monomer. The content of the (meth) acrylic acid ester unit in the (meth) acrylic polymer is usually 50% by weight or more, preferably 70% by weight or more, more preferably 80% by weight or more. The (meth) acrylic polymer may have a ring structure in the main chain. The ring structure is obtained by, for example, copolymerizing a (meth) acrylate monomer and a monomer having a ring structure, or polymerizing a monomer group including a (meth) acrylate monomer. By proceeding with the cyclization reaction, it is introduced into the main chain of the (meth) acrylic polymer. When the polymer has a ring structure in the main chain, the polymer is a (meth) acrylic polymer if the total content of the (meth) acrylic acid ester unit and the ring structure is 50% by weight or more.

  (Meth) acrylic acid ester units are, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, t- (meth) acrylic acid t- Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, benzyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxy (meth) acrylate Each of ethyl, 3-hydroxypropyl (meth) acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate, and 2,3,4,5-tetrahydroxypentyl (meth) acrylate It is a structural unit derived from a monomer. The (meth) acrylic polymer preferably has a methyl (meth) acrylate unit. In this case, optical properties and thermal stability of the finally obtained retardation film are improved. The (meth) acrylic polymer may have two or more (meth) acrylic acid ester units.

  The (meth) acrylic polymer may have a structural unit other than the (meth) acrylic acid ester unit. Such structural units include, for example, styrene, vinyl toluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, methacrylonitrile, ethylene, propylene, 4-methyl-1-pentene, acetic acid. It is a structural unit derived from each monomer of vinyl, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinyl pyrrolidone, and N-vinyl carbazole. The (meth) acrylic polymer may have two or more of these structural units. When the (meth) acrylic polymer has an N-vinylpyrrolidone unit or an N-vinylcarbazole unit, the degree of freedom in controlling the birefringence wavelength dispersibility in the finally obtained retardation film is improved. For example, in the visible light region, a retardation film exhibiting wavelength dispersion (so-called reverse wavelength dispersion) having a smaller birefringence (a smaller phase difference) as the wavelength of light becomes shorter can be obtained.

  When a cyclic structure is introduced into the main chain by a cyclization reaction after polymerization, the (meth) acrylic polymer is formed by copolymerization of a monomer group including a monomer having a hydroxyl group and / or a carboxylic acid group. Is preferred. Examples of the monomer having a hydroxyl group include methyl 2- (hydroxymethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, isopropyl 2- (hydroxymethyl) acrylate, butyl 2- (hydroxymethyl) acrylate, These are methyl 2- (hydroxyethyl) acrylate, methallyl alcohol, and allyl alcohol. Examples of the monomer having a carboxylic acid group include acrylic acid, methacrylic acid, crotonic acid, 2- (hydroxymethyl) acrylic acid, and 2- (hydroxyethyl) acrylic acid. Two or more of these monomers may be used. These monomers become a ring structure located in the main chain of the (meth) acrylic polymer by a cyclization reaction, but it is not necessary that all of the monomers change into a ring structure during the cyclization reaction. The (meth) acrylic polymer after the cyclization reaction may have a structural unit derived from these monomers.

  The weight average molecular weight of the (meth) acrylic polymer is preferably 10,000 to 500,000, more preferably 50,000 to 300,000.

  The (meth) acrylic polymer preferably has a ring structure in the main chain, and the acrylic resin film preferably contains a (meth) acrylic polymer having a ring structure in the main chain as a main component. In this case, the heat resistance and hardness of the finally obtained retardation film are improved. Moreover, the ring structure of the main chain contributes to the acrylic resin film exhibiting a large retardation by stretching.

  The ring structure that the (meth) acrylic polymer may have in the main chain is, for example, at least one selected from an N-substituted maleimide structure, a maleic anhydride structure, a glutarimide structure, a glutaric anhydride structure, and a lactone ring structure. It is a seed. The N-substituted maleimide structure is, for example, a cyclohexylmaleimide structure, a methylmaleimide structure, a phenylmaleimide structure, or a benzylmaleimide structure. From the viewpoint of the heat resistance of the finally obtained retardation film, the ring structure is preferably a lactone ring structure, an N-alkyl-substituted maleimide structure, a glutarimide structure, a maleic anhydride structure, or a glutaric anhydride structure. From the viewpoint of imparting a positive retardation to the finally obtained retardation film, the ring structure is preferably a lactone ring structure, a glutarimide structure, or a glutaric anhydride structure. From the viewpoint of improving the birefringence wavelength dispersibility in the finally obtained retardation film, the structure is preferably a lactone ring structure.

  The lactone ring structure is usually a 4- to 8-membered ring, preferably a 5- to 6-membered ring, more preferably a 6-membered ring from the viewpoint of structural stability. The lactone ring structure is, for example, a structure represented by the following formula (1).

In the formula (1), R ¹ , R ² and R ³ are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The organic residue is, for example, an alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, or a propyl group; an unsaturated aliphatic carbonization having 1 to 20 carbon atoms such as an ethenyl group or a propenyl group. A hydrogen group; an aromatic hydrocarbon group having 1 to 20 carbon atoms such as a phenyl group or a naphthyl group; one of the hydrogen atoms in the alkyl group, the unsaturated aliphatic hydrocarbon group or the aromatic hydrocarbon group; The above is a group substituted with at least one group selected from a hydroxyl group, a carboxyl group, an ether group and an ester group.

The lactone ring structure represented by the formula (1) is obtained by copolymerizing a monomer group including, for example, methyl methacrylate (MMA) and 2- (hydroxymethyl) methyl acrylate (MHMA), Adjacent MMA units and MHMA units in the coalescence can be formed by dealcoholization cyclocondensation. At this time, R ¹ is H, R ² is CH ₃ , and R ³ is CH ₃ .

  When the (meth) acrylic polymer has a ring structure in the main chain, the content of the ring structure in the polymer is not particularly limited, but is usually 5 to 90% by weight, preferably 10 to 70% by weight, and 10 -60 wt% is more preferable, and 10-50 wt% is more preferable. If the content of the ring structure is excessively large, the stretchability and handling properties of the acrylic resin film are lowered.

  The (meth) acrylic polymer having a ring structure in the main chain can be formed by a known method.

  Examples of the (meth) acrylic polymer having a lactone ring structure in the main chain include, for example, JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, It is a polymer described in JP 2005-146084 A, and can be formed by the method described in the publication.

  The (meth) acrylic polymer having a glutaric anhydride structure in the main chain is, for example, a polymer described in JP 2006-283013 A, JP 2006-335902 A, or JP 2006-274118 A. Yes, it can be formed by the method described in the publication.

  Examples of the (meth) acrylic polymer having a glutarimide structure in the main chain include, for example, JP-A-2006-309033, JP-A-2006-317560, JP-A-2006-328329, JP-A-2006-328334, JP-A-2006-337491, JP-A-2006-337492, JP-A-2006-337493, JP-A-2006-337569, JP-A-2007-009182 It can be formed by the method described in the publication.

  The acrylic resin film has a composition that expresses a phase difference by stretching. The acrylic resin film may contain a thermoplastic polymer other than the (meth) acrylic polymer as long as the effect of the present invention is obtained. Other thermoplastic polymers include, for example, polyethylene, polypropylene, ethylene-propylene copolymers, olefin polymers such as poly (4-methyl-1-pentene); polyvinyl chloride, polyvinylidene chloride, polychlorinated vinyl, etc. Styrene polymers such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, polybutylene terephthalate, polyethylene Polyester such as phthalate; Polyamide such as nylon 6, nylon 66, nylon 610; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide; Polyether ether ketone; Sulfone; polyethersulfones; polyoxyethylene benzylidene alkylene; polyamideimide; polybutadiene rubber or ABS resin containing an acrylic rubber, rubber-like polymer such as ASA resin; a.

  When the acrylic resin film contains a styrene polymer, the finally obtained retardation film becomes a negative retardation film depending on the content of the styrene polymer in the film. When the acrylic resin film contains a styrene polymer, the styrene polymer is preferably a styrene-acrylonitrile copolymer from the viewpoint of compatibility with the (meth) acrylic polymer. When the acrylic resin film contains ABS resin or ASA resin, depending on the content of the resin in the acrylic resin film, the finally obtained retardation film may be a negative retardation film or its flexibility may be improved. Or

  The content of the other thermoplastic polymer in the acrylic resin film is preferably 0 to 50% by weight, more preferably 0 to 40% by weight, further preferably 0 to 30% by weight, particularly preferably 0 to 20% by weight. is there.

  The acrylic resin film may contain materials other than the polymer, for example, additives. Additives include, for example, hindered phenol-based, phosphorus-based, sulfur-based antioxidants; light-resistant stabilizers, weather-resistant stabilizers, thermal stabilizers, and other stabilizers; reinforcing materials such as glass fibers and carbon fibers; UV absorbers such as tyrates, (2,2′-hydroxy-5-methylphenyl) benzotriazole, 2-hydroxybenzophenone; near infrared absorbers; difficulties such as tris (dibromopropyl) phosphate, triallyl phosphate, antimony oxide Antistatic agent composed of anionic, cationic and nonionic surfactants; Colorants such as inorganic pigments, organic pigments and dyes; Organic fillers, inorganic fillers; Antiblocking agents; Resin modifiers; Organic Fillers, inorganic fillers; plasticizers; lubricants; flame retardants.

  The content of the additive in the acrylic resin film is preferably 0 to 5% by weight, more preferably 0 to 2% by weight, and still more preferably 0 to 0.5% by weight.

  The Tg (glass transition temperature) of the acrylic resin film is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, still more preferably 115 ° C. or higher, and particularly preferably 120 ° C. or higher. Although the upper limit of Tg of an acrylic resin film is not specifically limited, From a viewpoint of the drawability of the said film, Preferably it is 170 degrees C or less.

  The (meth) acrylic polymer having a ring structure in the main chain increases the Tg of the acrylic resin film and the retardation film obtained by stretching the film, and improves the heat resistance.

  The thickness of an acrylic resin film is not specifically limited, Preferably it is 5-200 micrometers, More preferably, it is 10-100 micrometers.

  In the production method of the present invention, the surface of the acrylic resin film on which the easy-adhesion layer is formed is excellent without being subjected to surface treatment (for example, corona discharge treatment, plasma treatment, ozone spraying, ultraviolet irradiation, flame treatment, chemical treatment) in advance. An easy-adhesion layer having excellent adhesion is formed. For this reason, conventionally, the wet tension on the surface of the resin film when forming the easy-adhesion layer was preferably 40 mN / m or more, but the wet tension (on the dispersion) of the acrylic resin film surface used in the production method of the present invention was The wetting tension of the acrylic resin film surface before application may be less than 40 mN / m.

  The acrylic resin film may be an unstretched film or a uniaxially stretched film. When the acrylic resin film is a uniaxially stretched film, the stretching direction in the heating atmosphere in the production method of the present invention is preferably a direction orthogonal to the stretching direction of the uniaxially stretched film in the plane of the film. . In this case, the finally obtained retardation film is usually biaxially stretchable.

  When the acrylic resin film is a strip-shaped uniaxially stretched film, the stretching direction of the uniaxially stretched film is the flow direction when forming the film (so-called MD direction), and stretching in a heating atmosphere in the production method of the present invention Is preferably the width direction of the acrylic resin film (so-called TD direction). In this case, an efficient retardation film can be produced. In the present specification, stretching in the MD direction in the belt-shaped resin film is referred to as longitudinal stretching, and stretching in the width direction is referred to as lateral stretching.

  The acrylic resin film can be formed by a known method (for example, melt extrusion, casting).

  When the acrylic resin film is formed by melt extrusion, the steps from the formation of the acrylic resin film to the final obtaining of the retardation film can be continuously performed. In this case, the step of applying a urethane resin dispersion on the surface of the acrylic resin film and the step of stretching the acrylic resin film coated with the urethane resin dispersion in a heated atmosphere are continuously performed. In this specification, the dispersion | distribution application | coating process continuously implemented with the process of extending | stretching the acrylic resin film which apply | coated the dispersion is called in-line coating. In the production method of the present invention, a step of drawing an unstretched film to obtain an acrylic resin film that is a uniaxially stretched film, a step of applying a urethane resin dispersion on the surface of the acrylic resin film, and a urethane resin dispersion It is particularly preferable to continuously perform the step of stretching the acrylic resin film coated with the coating under a heating atmosphere.

  When the acrylic resin film has a strip shape, a roll-like retardation film (retardation film wound around a roll: retardation film roll) may be formed by the production method of the present invention. Specifically, for example, while transporting a belt-shaped acrylic resin film in the longitudinal direction of the film, a dispersion of urethane resin is applied to the surface of the film to form a coating film of the dispersion, and the coating film The acrylic resin film on which is formed is stretched in a heated atmosphere to form a belt-like retardation film having an easy-adhesion layer containing a urethane resin on the surface. Next, the formed retardation film is wound around a roll to obtain a retardation film roll. At this time, the dispersion preferably contains fine particles, and the average primary particle size of the fine particles is preferably more than 200 nm. Thereby, a retardation film roll in which the occurrence of blocking is further suppressed is obtained. As the length of the wound retardation film (length in the longitudinal direction) is larger, blocking is more likely to occur. However, the dispersion contains fine particles, and the average primary particle diameter of the fine particles exceeds 200 nm. When the thickness is large (for example, 3000 m or more), the occurrence of blocking is effectively suppressed.

[Application of dispersion containing urethane resin (adhesive composition)]
In the production method of the present invention, a urethane resin dispersion (adhesive composition) is applied to the surface of an acrylic resin film to form a coating film of the dispersion (coating process).

  In the coating process, a known method can be applied as a method of applying the urethane resin dispersion. Specifically, for example, a bar coating method, a roll coating method, a gravure coating method, a rod coating method, a slot orifice coating method, a curtain coating method, or a fountain coating method may be used.

  The thickness of the coating film formed in the coating process can be appropriately adjusted according to the thickness required when the coating film becomes an easy-adhesion layer.

  The urethane resin dispersion applied to the surface of the acrylic resin film is typically an emulsion of urethane resin particles.

  The urethane resin is not particularly limited, and is typically a resin obtained by reacting a polyol and a polyisocyanate. Any polyol having two or more hydroxyl groups in the molecule can be adopted as the polyol. The polyol is, for example, a polyacryl polyol, a polyester polyol, or a polyether polyol. Two or more polyols may be combined.

  The polyacryl polyol is typically a copolymer of a (meth) acrylic acid ester monomer and a monomer having a hydroxyl group. The (meth) acrylic acid ester monomer is, for example, methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, or cyclohexyl (meth) acrylate. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (Meth) acrylic acid hydroxyalkyl esters such as (meth) acrylic acid 4-hydroxybutyl and (meth) acrylic acid 2-hydroxypentyl; (meth) acrylic acid monoesters of polyhydric alcohols such as glycerin and trimethylolpropane; N -Methylol (meth) acrylamide.

  The polyacryl polyol may be a copolymer with further other monomers. The other monomer is not limited as long as it can be copolymerized with the (meth) acrylic acid ester monomer and the monomer having a hydroxyl group. Such other monomers include, for example, unsaturated monocarboxylic acids such as (meth) acrylic acid; unsaturated dicarboxylic acids such as maleic acid and anhydrides and mono- or diesters thereof; unsaturated nitriles such as (meth) acrylonitrile Unsaturated amides such as (meth) acrylamide and N-methylol (meth) acrylamide; Vinyl esters such as vinyl acetate and vinyl propionate; Vinyl ethers such as methyl vinyl ether; α-olefins such as ethylene and propylene; Halogenated α, β-unsaturated aliphatic monomers such as vinyl chloride and vinylidene chloride; α, β-unsaturated aromatic monomers such as styrene and α-methylstyrene.

  The polyester polyol is typically obtained by reacting a polybasic acid component with a polyol component. Examples of the polybasic acid component include orthophthalic acid, isophthalic acid, terephthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and tetrahydrophthalic acid. Aromatic dicarboxylic acids; oxalic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, dodecanedicarboxylic acid, octadecanedicarboxylic acid, tartaric acid, alkylsuccinic acid, Aliphatic dicarboxylic acids such as linolenic acid, maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid; hexahydrophthalic acid, tetrahydrophthalic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, etc. Alicyclic dicarbo Acid; or their acid anhydrides are reactive derivative such as an alkyl ester, acid halide.

  Examples of the polyol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, and 1,6-hexanediol. 1,8-octanediol, 1,10-decanediol, 1-methyl-1,3-butylene glycol, 2-methyl-1,3-butylene glycol, 1-methyl-1,4-pentylene glycol, 2 -Methyl-1,4-pentylene glycol, 1,2-dimethyl-neopentyl glycol, 2,3-dimethyl-neopentyl glycol, 1-methyl-1,5-pentylene glycol, 2-methyl-1,5 -Pentylene glycol, 3-methyl-1,5-pentylene glycol, 1,2-dimethylbutylene Coal, 1,3-dimethylbutylene glycol, 2,3-dimethylbutylene glycol, 1,4-dimethylbutylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediol, bisphenol A, bisphenol F, hydrogenated bisphenol A, and hydrogenated bisphenol F.

  The polyether polyol is typically obtained by adding an alkylene oxide to a polyhydric alcohol by ring-opening polymerization. The polyhydric alcohol is, for example, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerin, or trimethylolpropane. The alkylene oxide is, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran.

  Examples of the polyisocyanate include tetramethylene diisocyanate, dodecamethylene diisocyanate, 1,4-butane diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, Aliphatic diisocyanates such as 2-methylpentane-1,5-diisocyanate and 3-methylpentane-1,5-diisocyanate; isophorone diisocyanate, hydrogenated xylylene diisocyanate, 4,4'-cyclohexylmethane diisocyanate, 1,4-cyclohexane Alicyclic diisodies such as diisocyanate, methylcyclohexylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane Anate; tolylene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1 , 5-naphthylene diisocyanate, xylylene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate and other aromatic diisocyanates; dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, α, α, α, α-tetramethylxylylene An aromatic aliphatic diisocyanate such as range isocyanate.

  The urethane resin preferably has a carboxyl group. By having a carboxyl group, the performance (adhesiveness) of the easy adhesion layer is improved. The urethane resin having a carboxyl group can be obtained, for example, by reacting a chain extender having a free carboxyl group in addition to a polyol and a polyisocyanate. Examples of the chain extender having a free carboxyl group are dihydroxycarboxylic acid and dihydroxysuccinic acid. The dihydroxycarboxylic acid is a dialkylol alkanoic acid such as dimethylol alkanoic acid (for example, dimethylol acetic acid, dimethylol butanoic acid, dimethylol propionic acid, dimethylol butyric acid, dimethylol pentanoic acid).

  The acid value of the urethane resin is preferably 10 or more, more preferably 10 to 50, and particularly preferably 20 to 45. In these cases, the performance of the easy adhesion layer is further improved.

  The urethane resin may be obtained by reaction with other polyols or other chain extenders in addition to the components described above. Other polyols include, for example, sorbitol, 1,2,3,6-hexanetetraol, 1,4-sorbitan, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerin, trimethylolethane , Trimethylolpropane, pentaerythritol, and other polyols having three or more hydroxyl groups. Other chain extenders include, for example, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 1,6- Glycols such as hexanediol and propylene glycol; Aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, 1,4-butanediamine, and aminoethylethanolamine; Fats such as isophorone diamine and 4,4'-dicyclohexylmethanediamine Cyclic diamines; aromatic diamines such as xylylenediamine and tolylenediamine.

  The urethane resin can be formed by applying a known method. This method is, for example, a one-shot method in which each component is reacted at once, or a multi-stage method in which the components are reacted stepwise. The urethane resin having a carboxyl group is preferably formed by a multistage method since the introduction of the carboxyl group is easy. The catalyst used for forming the urethane resin is not particularly limited.

  The dispersion of the urethane resin is preferably an aqueous dispersion. Compared to organic solvent-based dispersions, water-based dispersions have less environmental impact and are excellent in workability. The aqueous dispersion may contain a neutralizing agent. In this case, the stability of the urethane resin in the aqueous dispersion medium is improved. Examples of the neutralizing agent include ammonia, N-methylmorpholine, triethylamine, dimethylethanolamine, methyldiethanolamine, triethanolamine, morpholine, tripropylamine, ethanolamine, triisopropanolamine, 2-amino-2-methyl-1- Propanol.

  When the urethane resin dispersion is water-based, it is preferable to use an organic solvent that is inert to the polyisocyanate and is compatible with water when the urethane resin is formed. Examples of organic solvents include ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate; ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; ether solvents such as dioxane, tetrahydrofuran, and propylene glycol monomethyl ether. is there.

  The number average molecular weight of the urethane resin is preferably 5,000 to 600,000, more preferably 10,000 to 400,000.

  The content of the urethane resin in the urethane resin dispersion is preferably 1.5 to 15% by weight, and more preferably 2 to 10% by weight. When the content ratio is within these ranges, the coating property of the dispersion is high.

  The urethane resin dispersion preferably contains a crosslinking agent, and in this case, the performance of the easy-adhesion layer is improved. The crosslinking agent is not particularly limited. When the urethane resin dispersion is aqueous, a water-soluble type is preferred. When the urethane resin has a carboxyl group, the crosslinking agent is preferably a polymer having a group capable of reacting with the carboxyl group. Examples of the group capable of reacting with a carboxyl group are an organic amino group, an oxazoline group, an epoxy group, and a carbodiimide group, and an oxazoline group is preferable. A cross-linking agent having an oxazoline group has a long pot life at room temperature when mixed with a urethane resin, and has a good workability because a cross-linking reaction proceeds by heating. The polymer is, for example, a (meth) acrylic polymer or a styrene / acrylic polymer, and a (meth) acrylic polymer is preferable.

  The urethane resin dispersion preferably includes fine particles. In this case, the anti-blocking property of the finally formed retardation film is improved.

  The fine particles are not particularly limited, and are, for example, water-dispersible fine particles, which may be either inorganic fine particles or organic fine particles. Inorganic fine particles include, for example, inorganic oxides such as silica, titania, alumina, zirconia, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, calcium phosphate, and the like. It is. The organic fine particles are, for example, fine particles of silicone resin, fluorine resin, or acrylic resin.

  The fine particles are preferably silica fine particles. Silica fine particles are highly effective in improving anti-blocking properties. Moreover, since it is excellent in transparency, coloring of the retardation film finally obtained and increase in a haze rate do not easily occur. In addition to this, the silica fine particles have good dispersibility and dispersion stability in the dispersion of the urethane resin, and have high adhesion to the acrylic resin film.

  When the urethane resin dispersion is aqueous, the fine particles are preferably blended as an aqueous dispersion such as colloidal silica. Colloidal silica may be a commercially available product, for example, Quartron PL series manufactured by Fuso Chemical Industry, Snowtex series manufactured by Nissan Chemical Industries, Aerodisp series and Aerosil series manufactured by Nippon Aerosil, and Seahoster series manufactured by Nippon Shokubai.

  When the urethane resin dispersion includes fine particles, the content of the fine particles in the dispersion is preferably less than 1% by weight, more preferably less than 0.5% by weight, and even more preferably less than 0.3% by weight. When the content of the fine particles is excessively large, the strength of the formed easy-adhesion layer may be reduced.

  The particle size of the fine particles is not particularly limited. When the formed retardation film is wound around a roll to obtain a retardation film roll, the average primary particle diameter of the fine particles is preferably more than 200 nm, more preferably 250 nm or more from the viewpoint of suppressing the occurrence of blocking. At this time, the upper limit of the average primary particle diameter of the fine particles is not limited, but is preferably 1000 nm or less, more preferably 500 nm or less, still more preferably 400 nm or less, and particularly preferably 350 nm or less. By using such fine particles, blocking resistance can be efficiently imparted to the retardation film even with a small amount of added particles while maintaining transparency. The average primary particle diameter of the fine particles can be determined by a particle size distribution measuring device. For example, in an equivalent spherical distribution measured with a particle size distribution measuring device, a particle diameter of 50% in terms of an integrated volume fraction integrated from the large particle side can be used as the average primary particle diameter (d50). In this example, Submicron Particle Sizer NICOMP380 manufactured by Particle Sizing Systems was used as the particle size distribution measuring apparatus.

  The urethane resin dispersion may contain any material other than those described above as long as the effects of the present invention are obtained. Examples of the material include a dispersion stabilizer, a thixotropic agent, an antioxidant, an ultraviolet absorber, an antifoaming agent, a thickener, a dispersant, a surfactant, a catalyst, and an antistatic agent.

[Stretching]
In the production method of the present invention, after the coating step, the acrylic resin film on which the urethane resin dispersion coating film is formed is stretched in a heated atmosphere (stretching step). By this stretching, the acrylic resin film becomes a retardation film, and the coating film on the surface of the film is heat-treated by heat in a heating atmosphere to become an easy adhesion layer.

  The acrylic resin film may be stretched according to a known method. Stretching is, for example, uniaxial stretching or biaxial stretching. Uniaxial stretching is typically free end uniaxial stretching in which the change in the width direction of the resin film is free. It may be fixed end uniaxial stretching in which the change in the width direction of the resin film is fixed. The biaxial stretching is typically sequential biaxial stretching, but simultaneous biaxial stretching in which longitudinal and transverse stretching are simultaneously performed can also be suitably used. Furthermore, the film roll may be stretched in an oblique direction.

  The stretching temperature is preferably in the vicinity of Tg of the acrylic resin film. Specifically, (Tg-30) ° C to (Tg + 100) ° C is preferable, and (Tg-20) ° C to (Tg + 80) ° C is more preferable. When the stretching temperature is lower than (Tg-30) ° C., a sufficient stretching ratio for obtaining a retardation film may not be obtained. If the stretching temperature exceeds (Tg + 100) ° C., the resin constituting the film may flow, and stable stretching may not be performed. In addition, since Tg of an acrylic resin film is 100 degreeC or more normally, the said temperature range is a temperature range high enough for the coating film of the dispersion of a urethane resin to be heat-processed to an easily bonding layer.

  The draw ratio can be adjusted, for example, in the range of 1.1 to 25 times, preferably in the range of 1.3 to 10 times, depending on the retardation to be obtained as the retardation film. When the draw ratio is less than 1.1 times, a sufficient phase difference may not be exhibited. When the draw ratio exceeds 25 times, the effect of increasing the draw ratio is not observed.

  The stretching speed is, for example, 10 to 20,000% / min, and preferably 100 to 10,000% / min. An excessively high stretching speed causes breakage of the acrylic resin film.

  A known stretching machine can be used for stretching the acrylic resin film in a heated atmosphere. The longitudinal stretching machine is not particularly limited, but an oven stretching machine is preferable. The oven vertical stretching machine is generally composed of an oven and transport rolls provided on the inlet side and the outlet side of the oven, respectively. The resin film is stretched in the transport direction by giving a peripheral speed difference between the transport roll on the entrance side of the oven and the transport roll on the exit side. The transverse stretching machine is not particularly limited, but a tenter stretching machine is preferable. The tenter stretching machine may be either a grip type or a pin type, but the grip type is preferable because the resin film hardly tears. A grip-type tenter stretching machine is generally composed of a clip traveling device for transverse stretching and an oven. In the clip traveling device, the resin film is conveyed in a state where the lateral end of the resin film is sandwiched between the clips. At this time, the resin rail is stretched laterally by opening the guide rail of the clip traveling device and widening the distance between the left and right two rows of clips. In the grip-type tenter stretching machine, simultaneous biaxial stretching is also possible by providing a clip expansion / contraction function with respect to the transport direction of the resin film. Moreover, the diagonal stretcher | stretcher which carries out the tension | pulling stretching in the conveyance direction of the said film at a different speed on the right and left of the extending direction of the resin film may be used.

[Phase difference film]
In the production method of the present invention, a retardation film having an easy adhesion layer is formed. The easy-adhesion layer contains the urethane resin contained in the urethane resin dispersion. When the said dispersion contains a crosslinking agent, an easily bonding layer has the crosslinked structure of the urethane resin based on the said crosslinking agent. When the dispersion contains fine particles, the easy-adhesion layer contains the fine particles.

  The thickness of the easily bonding layer is, for example, 100 to 1000 nm, preferably 150 to 600 nm, and more preferably 250 to 450 nm.

  The retardation film obtained by the production method of the present invention has, for example, an in-plane retardation with respect to light having a wavelength of 589 nm of 10 nm or more, preferably 20 nm or more, and more preferably 50 nm or more.

  In the production method of the present invention, a retardation film showing a large in-plane retardation Re is obtained depending on the composition of the acrylic resin constituting the acrylic resin film and the stretching conditions. For example, a retardation film having an in-plane retardation Re of 100 to 150 nm with respect to light having a wavelength of 589 nm is obtained. The retardation film is suitable for use as a λ / 4 plate.

  In the production method of the present invention, a retardation film showing a large thickness direction retardation Rth is obtained depending on the composition of the acrylic resin constituting the acrylic resin film and the stretching conditions. For example, a retardation film having a thickness direction retardation Rth of 10 to 500 nm, preferably 50 to 200 nm, for light having a wavelength of 589 nm can be obtained.

  The “phase difference value” is also referred to as a retardation value. The in-plane phase difference Re is defined by the formula Re = (nx−ny) × d, and the thickness direction phase difference Rth is defined by the formula Rth = [(nx + ny) / 2−nz] × d. Here, nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the direction perpendicular to the slow axis in the film plane, nz is the refractive index in the thickness direction of the film, and d is the thickness of the film. (Nm). The slow axis direction is a direction in which the refractive index becomes maximum in the film plane. Those having a refractive index in the stretching direction are said to have positive birefringence, and those having a refractive index in the direction perpendicular to the stretching direction in the film plane are said to have negative birefringence.

  In the manufacturing method of this invention, as long as the effect of this invention is acquired, you may have arbitrary processes other than the process mentioned above. This step is, for example, a step of laminating a further layer (for example, a resin layer) on the formed retardation film or a step of performing post-processing such as coating treatment or surface treatment on the formed retardation film.

  The retardation film obtained by the production method of the present invention is suitable for use in an image display device such as an LCD. The retardation film can be used, for example, for LCD color tone compensation and viewing angle compensation.

  Since the retardation film obtained by the production method of the present invention has an easy-adhesion layer excellent in adhesiveness, it can be used in a form other than that normally used as a retardation film. Specifically, for example, a form that is used by being bonded to a polarizer included in an LCD can be considered. In this case, the retardation film has both a function as a normal retardation film for color tone compensation or viewing angle compensation and a function as a polarizer protective film for protecting the polarizer. This form is advantageous for making the LCD thinner and more functional because the polarizer protective film having no retardation which has been conventionally used separately from the retardation film can be omitted.

  The retardation film obtained by the production method of the present invention may be wound around a roll.

[Phase difference film roll]
The retardation film roll of this invention has the structure by which the retardation film in which the easily bonding layer containing a urethane resin and the microparticles | fine-particles whose average primary particle diameter exceeds 200 nm was formed in the surface was wound. In the retardation film roll of the present invention, the length of the wound retardation film in the longitudinal direction is 3000 m or more.

  The average primary particle diameter of the fine particles is preferably 250 nm or more.

  The retardation film wound on the retardation film roll of the present invention and having an easy adhesion layer formed on the surface thereof is as described above in the description of the retardation film obtained by the production method of the present invention. However, the easy-adhesion layer contains fine particles, the average primary particle diameter of the fine particles exceeds 200 nm, and the length of the retardation film in the longitudinal direction is 3000 m or more. When the length of the retardation film in the longitudinal direction is 3000 m or more, production efficiency increases when the retardation film and another optical member (for example, a polarizer) are bonded.

  Hereinafter, the present invention will be described in more detail with reference to examples. The present invention is not limited to the following examples.

  Initially, the evaluation method of the polymer produced in a present Example, an acrylic resin film, retardation film, and retardation film roll is shown.

[Polymer composition analysis]
The composition of the polymer produced in each production example was calculated from the amount of unreacted monomer remaining in the obtained polymerization solution. The amount of unreacted monomer was measured by gas chromatography (manufactured by Shimadzu Corporation, GC17A).

[Weight average molecular weight]
The weight average molecular weight of the polymer was determined in terms of polystyrene using gel permeation chromatography (GPC). The apparatus and measurement conditions used for the measurement are as follows.
System: Made by Tosoh Column: TSK-GEL SuperHZM-M 6.0 × 150 2 in series Guard column: TSK-GEL SuperHZ-L 4.6 × 35 1 Reference column: TSK-GEL SuperH-RC 6.0 × 150 2 in series Eluent: Chloroform Flow rate 0.6 mL / min Column temperature: 40 ° C.

[Glass transition temperature (Tg)]
The Tg of the polymer was determined by the midpoint method according to ASTM-D-3418. Specifically, using a differential scanning calorimeter (manufactured by Rigaku, DSC-8230), a sample of about 10 mg was heated from 30 ° C. to 250 ° C. in a nitrogen flow (50 mL / min) atmosphere (heating rate 10 ° C. / Min) and the DSC curve obtained. Α-alumina was used as a reference.

[Film thickness]
The thickness of the film was measured using a Digimatic micrometer (manufactured by Mitutoyo Corporation).

[In-plane retardation Re]
The in-plane retardation Re (Re for light with a wavelength of 589 nm) of the retardation film produced in each example and comparative example was measured using a fully automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WR).

[Thickness direction retardation Rth]
The retardation Rth (Rth for light with a wavelength of 589 nm) in the thickness direction of the retardation film produced in each example and comparative example was determined using a fully automatic birefringence meter (manufactured by Oji Scientific Instruments, KOBRA-WR). The calculation was made based on the values measured by tilting the phase axis by 40 ° using the tilt axis.

[Wet tension]
The wetting tension on the film surface was determined in accordance with the JIS K6768 “Plastic-film and sheet-wetting tension test method”.

[Adhesiveness]
The adhesiveness of the easy-adhesion layer in the retardation film produced in each example and comparative example was evaluated as follows.

A polyvinyl alcohol-based resin (manufactured by Nippon Synthetic Chemical Co., Ltd., Goosephimer Z-200, average polymerization degree 1200) was dissolved in pure water to obtain an adhesive composition having a solid content concentration of 4% by weight. Next, the obtained composition was uniformly applied to the surface of the easy-adhesion layer in the produced retardation film so that the thickness after drying was 50 μm, and then the whole was kept in a hot air dryer maintained at 80 ° C. It was accommodated for 5 minutes and dried to form an adhesive layer on the surface of the easy adhesion layer. The evaluation sample thus obtained was subjected to a cross-cut test in accordance with JIS K5400 to evaluate the adhesion of the easy-adhesion layer in the produced retardation film. Specifically, a 1 mm square grid cut is formed on the adhesive layer in the sample for evaluation using a sharp blade, and then a 25 mm wide cellophane tape conforming to the provisions of JIS Z1522 is applied to the surface of the layer. It was stuck with a wooden spatula. Thereafter, the cellophane tape was peeled off, and the state of the adhesive layer after the cellophane tape was peeled off was visually confirmed. The evaluation criteria are as follows.
○: No peeling of the adhesive layer from the retardation film was confirmed.
X: Peeling of the adhesive layer from the retardation film was confirmed.

[Blocking resistance]
The blocking resistance of the retardation film roll produced in Examples 8 to 10 was evaluated as follows. The phase difference film was wound up to produce a film roll, which was then left for 3 months. After leaving, the film surface was visually observed over the entire length of the film while feeding out the retardation film from the film roll, and blocking resistance was evaluated. The evaluation criteria are as follows.
○: No blocking marks were observed on the retardation film.
X: Blocking marks were confirmed on the retardation film.

(Production Example 1)
In a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction pipe, 40 parts by weight of methyl methacrylate (MMA), 10 parts by weight of methyl 2- (hydroxymethyl) acrylate (MHMA), and toluene 50 as a polymerization solvent Part by weight and 0.025 part by weight of an antioxidant (Adeka Stub 2112, manufactured by ADEKA) were charged, and the temperature was raised to 105 ° C. while passing nitrogen through this. When the reflux accompanying the temperature rise began, 0.05 parts by weight of t-amylperoxyisononanoate (Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and the t-amylperoxyisononoate was added. While 0.10 parts by weight of nanoate was added dropwise over 3 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

  Next, 0.05 parts by weight of 2-ethylhexyl phosphate (Phoslex A-8, manufactured by Sakai Chemical Industry Co., Ltd.) is added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst). The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 2 hours under reflux at 110 ° C. Next, the obtained polymerization solution was passed through a heat exchanger and heated to 240 ° C., and the cyclization condensation reaction was further advanced at the temperature.

Next, the obtained polymerization solution was subjected to a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1 and a forevent number of 4 (first and 2, a third and a fourth vent), a side feeder is provided between the third vent and the fourth vent, and a leaf disk type polymer filter (filtration accuracy 5 μm, filtration area 1.5 m at the tip) ² ) was introduced into a vent type screw twin screw extruder (L / D = 52) at a processing speed of 70 parts by weight / hour (resin amount conversion), and devolatilization was performed. At that time, 0.34 parts by weight of ion-exchanged water was added after the first vent at a charging rate of 1.06 parts by weight / hour with a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator. After the second and third vents, the charging was performed at a charging speed of / hour. In the mixed solution of the antioxidant / cyclization catalyst deactivator, 50 parts by weight of an antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010) and 35 parts by weight of zinc octylate (Nippon Chemical Industry Co., Ltd.) Manufactured by Nikka Octics Zinc (3.6%) was dissolved in 200 parts by weight of toluene. In addition, at the time of devolatilization, pellets of styrene-acrylonitrile copolymer (AS resin: ratio of styrene unit / acrylonitrile unit is 73% by weight / 27% by weight, weight average molecular weight is 220,000) from the side feeder. , And was charged at a loading speed of 30 parts by weight / hour.

  After completion of devolatilization, the resin in the molten state remaining in the extruder is discharged while filtering through a polymer filter from the tip of the extruder, pelletized by a pelletizer, and has a lactone ring structure in the main chain (meta) An acrylic resin transparent pellet (1A) containing an acrylic polymer as a main component (content: 70% by weight) and further containing a styrene-acrylonitrile copolymer at a content of 30% by weight was obtained. The acrylic resin constituting the pellet (1A) had a Tg of 122 ° C. and a weight average molecular weight of 1480,000.

(Production Example 2)
The material charged after the third vent of the extruder was from ion-exchanged water, an emulsion of fine particles of polymethyl methacrylate crosslinked (manufactured by Nippon Shokubai, Epostor MX-50W, average particle size 0.06 μm, solid content 4. 8% by weight), and the main component is a (meth) acrylic polymer having a lactone ring structure in the main chain in the same manner as in Production Example 1, except that the charging rate is 2.07 parts by weight / hour. Further, transparent acrylic resin pellets (2A) containing a styrene-acrylonitrile copolymer were obtained. The acrylic resin constituting the pellet (2A) had a Tg of 122 ° C. and a weight average molecular weight of 1480,000.

(Production Example 3)
In a reaction kettle equipped with a stirrer, temperature sensor, cooling pipe and nitrogen introduction pipe, 40 parts by weight of methyl methacrylate (MMA), 10 parts by weight of methyl 2- (hydroxymethyl) acrylate (MHMA), and toluene 50 as a polymerization solvent Part by weight and 0.025 part by weight of an antioxidant (Adeka Stub 2112, manufactured by ADEKA) were charged, and the temperature was raised to 105 ° C. while passing nitrogen through this. When the reflux accompanying the temperature rise began, 0.05 parts by weight of t-amylperoxyisononanoate (Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and the t-amylperoxyisononoate was added. While 0.10 parts by weight of nanoate was added dropwise over 3 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

  Next, 0.05 parts by weight of 2-ethylhexyl phosphate (Phoslex A-8, manufactured by Sakai Chemical Industry Co., Ltd.) is added to the resulting polymerization solution as a catalyst for the cyclization condensation reaction (cyclization catalyst). The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 2 hours under reflux at 110 ° C. Next, the obtained polymerization solution was passed through a heat exchanger and heated to 240 ° C., and the cyclization condensation reaction was further advanced at the temperature.

Next, the obtained polymerization solution was subjected to a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1 and a forevent number of 4 (first and 2, a third and a fourth vent), a side feeder is provided between the third vent and the fourth vent, and a leaf disk type polymer filter (filtration accuracy 5 μm, filtration area 1.5 m at the tip) ² ) was introduced into a vent type screw twin screw extruder (L / D = 52) at a processing rate of 66 parts by weight / hour (resin amount conversion) to perform devolatilization. In this case, 0.34 parts by weight of ion-exchanged water was added after the first vent at a charging rate of 1.00 parts by weight / hour with a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator. After the second and third vents, the charging was performed at a charging speed of / hour. In the mixed solution of the antioxidant / cyclization catalyst deactivator, 50 parts by weight of an antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010) and 35 parts by weight of zinc octylate (Nippon Chemical Industry Co., Ltd.) Manufactured by Nikka Octics Zinc (3.6%) was dissolved in 200 parts by weight of toluene. In addition, at the time of devolatilization, pellets of styrene-acrylonitrile copolymer (AS resin: ratio of styrene unit / acrylonitrile unit is 73% by weight / 27% by weight, weight average molecular weight is 220,000) from the side feeder. , 34 parts by weight / hour.

  After completion of devolatilization, the resin in the molten state remaining in the extruder is discharged while filtering through a polymer filter from the tip of the extruder, pelletized by a pelletizer, and has a lactone ring structure in the main chain (meta) An acrylic resin transparent pellet (3A) containing an acrylic polymer as a main component (content: 66% by weight) and further containing a styrene-acrylonitrile copolymer at a content of 34% by weight was obtained. The acrylic resin constituting the pellet (3A) had a Tg of 121 ° C. and a weight average molecular weight of 153,000.

(Production Example 4)
In a reaction kettle equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introduction pipe, 35 parts by weight of methyl methacrylate (MMA), 15 parts by weight of methyl 2- (hydroxymethyl) acrylate (MHMA), and toluene 50 as a polymerization solvent Part by weight and 0.025 part by weight of an antioxidant (Adeka Stub 2112, manufactured by ADEKA) were charged, and the temperature was raised to 105 ° C. while passing nitrogen through this. When the reflux accompanying the temperature increase started, 0.03 part by weight of t-amylperoxyisononanoate (Arkema Yoshitomi, trade name: Luperox 570) was added as a polymerization initiator, and the t-amylperoxyisononoate was added. While 0.06 parts by weight of nanoate was added dropwise over 3 hours, solution polymerization was allowed to proceed under reflux at about 105 to 110 ° C., followed by further aging for 4 hours.

  Next, 0.1 parts by weight of 2-ethylhexyl phosphate (Phoslex A-8, manufactured by Sakai Chemical Industry Co., Ltd.) as a catalyst for the cyclization condensation reaction (cyclization catalyst) was added to the obtained polymerization solution, The cyclization condensation reaction for forming a lactone ring structure was allowed to proceed for 2 hours under reflux at 100 ° C. Next, the obtained polymerization solution was passed through a heat exchanger and heated to 240 ° C., and the cyclization condensation reaction was further advanced at the temperature.

Next, the obtained polymerization solution was subjected to a barrel temperature of 240 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1 and a forevent number of 4 (first and 2, 3rd and 4th vents), a vent type screw twin screw extruder (L / D = 52) having a leaf disk type polymer filter (filtration accuracy 5 μm, filtration area 1.5 m ² ) at the tip. ) And was devolatilized at a processing rate of 100 parts by weight / hour (resin amount conversion). At that time, 0.49 parts by weight of ion-exchanged water was added after the first vent at a charging rate of 2.27 parts by weight / hour with a separately prepared mixed solution of antioxidant / cyclization catalyst deactivator. After the second and third vents, the charging was performed at a charging speed of / hour. In the mixed solution of the antioxidant / cyclization catalyst deactivator, 50 parts by weight of an antioxidant (manufactured by Ciba Specialty Chemicals, Irganox 1010) and 35 parts by weight of zinc octylate (Nippon Chemical Industry Co., Ltd.) Manufactured by Nikka Octics Zinc (3.6%) was dissolved in 200 parts by weight of toluene.

  After completion of devolatilization, the resin in the molten state remaining in the extruder is discharged while filtering through a polymer filter from the tip of the extruder, pelletized by a pelletizer, and has a lactone ring structure in the main chain (meta) A transparent pellet (4A) of an acrylic resin made of an acrylic polymer was obtained. The acrylic resin constituting the pellet (4A) had a Tg of 140 ° C. and a weight average molecular weight of 1270,000.

(Production Example 5)
A (meth) acrylic polymer (manufactured by Evonik Degussa, Pleximimide 8813) having a glutarimide structure in the main chain and the styrene-acrylonitrile copolymer used in Production Example 1 were kneaded at a weight ratio of 70/30, and glutarimide Transparent acrylic resin pellets (5A) containing a (meth) acrylic polymer having a structure in the main chain as a main component (content is 70% by weight) and further containing styrene-acrylonitrile copolymer at a content of 30% by weight Obtained. A twin screw extruder was used for kneading, and the kneading temperature was 240 ° C. The acrylic resin constituting the pellet (5A) had a Tg of 126 ° C. and a weight average molecular weight of 142,000.

(Manufacture example 6: Preparation of an easily bonding composition (1B))
19 parts by weight of urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35% by weight), 1.3 parts by weight of cross-linking agent (manufactured by Nippon Shokubai, Epocross WS-700, solid content 25% by weight), amorphous silica fine particles Emulsion (Nippon Shokubai Co., Ltd., Seahoster KE-W30, average particle size (primary particle size) 0.28 μm, solid content 20% by weight) 0.17 parts by weight and pure water 79 parts by weight were mixed to form an emulsion dispersion The easy-adhesion composition (1B) which is a body was obtained.

(Production Example 7: Preparation of easy-adhesion composition (2B))
19 parts by weight of urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35% by weight), 1.3 parts by weight of cross-linking agent (manufactured by Nippon Shokubai, Epocross WS-700, solid content 25% by weight), amorphous silica fine particles Emulsion (Nippon Shokubai Co., Ltd., Seahoster KE-W10, average particle diameter (primary particle diameter) 0.11 μm, solid content 16% by weight) 0.23 parts by weight and pure water 79 parts by weight are mixed to form an emulsion dispersion An easy-adhesion composition (2B) which was a body was obtained.

(Production Example 8: Preparation of easy-adhesive composition (3B))
14 parts by weight of an acrylic resin dispersion (manufactured by BASF, JONCRYL 631, solid content 50% by weight) and 86 parts by weight of pure water were mixed to obtain an easily adhesive composition (3B).

(Production Example 9: Preparation of easy-adhesive composition (4B))
19 parts by weight of urethane resin (Daiichi Kogyo Seiyaku Co., Ltd., Superflex 210, solid content 35% by weight), 1.3 parts by weight of crosslinking agent (manufactured by Nippon Shokubai Co., Ltd., Epocros WS-700, solid content 25% by weight), acrylic fine particles Emulsion (manufactured by Nippon Shokubai Co., Ltd., MX-100W, average particle size (primary particle size) 0.15 μm, solid content 10% by weight) 0.36 parts by weight and pure water 79 parts by weight are mixed to obtain an emulsion-like dispersion. An easy-adhesion composition (4B) was obtained.

Example 1
The acrylic resin pellets (1A) produced in Production Example 1 were melt extruded at 270 ° C. using a single-screw extruder equipped with a polymer filter (filtration accuracy: 5 μm) and a T-die at the tip to form a strip having a thickness of 220 μm. A film was formed. Next, the formed film is continuously supplied to an oven longitudinal stretching machine following melt extrusion, and stretched at a stretching temperature of 142 ° C. in the longitudinal direction of the film (flow direction during melt extrusion). The film was stretched (longitudinal stretching) at a magnification of 1.5.

  Furthermore, the thickness of the coating film after drying the easy-adhesive composition (1B) prepared in Production Example 6 on the one main surface of the acrylic resin film after longitudinal stretching by the gravure coating method is 1050 nm. After being applied (in-line coating), the acrylic resin film was supplied as it was to a tenter transverse stretching machine, and stretched in the width direction (lateral stretching) at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times. In this manner, a retardation film (thickness: 58 μm) made of an acrylic resin and having an easy adhesion layer (thickness: 350 nm) containing a urethane resin formed on one main surface was obtained.

(Example 2)
In place of the easy-adhesive composition (1B), an easy-adhesive layer comprising an acrylic resin and containing a urethane resin in the same manner as in Example 1 except that the easy-adhesive composition (2B) prepared in Production Example 7 was used ( A retardation film (thickness: 58 μm) having a thickness of 350 nm formed on one main surface was obtained.

(Example 3)
An easy-adhesion layer (thickness 350 nm) made of an acrylic resin and containing a urethane resin in the same manner as in Example 1 except that the acrylic resin pellet (2A) produced in Production Example 2 was used instead of the pellet (1A). ) Was obtained on one main surface to obtain a retardation film (thickness: 58 μm).

Example 4
Instead of the pellet (1A), the acrylic resin pellet (3A) produced in Production Example 3 was used, the stretching temperature for longitudinal stretching was 129 ° C, the stretching ratio was 2.5 times, and the stretching temperature for transverse stretching was 126 ° C, stretching. It was made of an acrylic resin and made of urethane in the same manner as in Example 1 except that the magnification was 2.0 times and the easy-adhesive composition (1B) was applied so that the thickness of the coating film after drying was 700 nm. A retardation film (thickness: 58 μm) having an easy-adhesion layer (thickness: 350 nm) containing a resin formed on one main surface was obtained.

(Example 5)
Instead of the pellet (1A), the acrylic resin pellet (4A) produced in Production Example 4 was used, the thickness of the film formed by melt extrusion was 150 μm, the stretching temperature for longitudinal stretching was 160 ° C., and the stretching ratio was 1 Except that the stretching temperature for transverse stretching was 160 ° C., the stretching ratio was 1.8 times, and the easy-adhesive composition (1B) was applied so that the thickness of the coating film after drying was 630 nm. In the same manner as in Example 1, a retardation film (thickness 54 nm) made of an acrylic resin and having an easy adhesion layer (thickness 350 nm) containing a urethane resin formed on one main surface was obtained.

(Example 6)
The acrylic resin pellet (5A) produced in Production Example 5 was used instead of the pellet (1A), the thickness of the film formed by melt extrusion was 150 μm, the stretching temperature for longitudinal stretching was 130 ° C., and the stretching ratio was 1 Except that the stretching temperature for transverse stretching was 130 ° C., the stretching ratio was 1.8 times, and the easy-adhesive composition (1B) was applied so that the thickness of the coating film after drying was 630 nm. In the same manner as in Example 1, a retardation film (thickness 53 nm) made of an acrylic resin and having an easy adhesion layer (thickness 350 nm) containing a urethane resin formed on one main surface was obtained.

(Example 7)
An easy-adhesive layer (thickness 350 nm) made of an acrylic resin and containing a urethane resin was used in the same manner as in Example 1 except that the easy-adhesive composition (1B) was applied to both main surfaces of the acrylic resin film. A retardation film (thickness: 58 μm) formed on the surface was obtained.

(Comparative Example 1)
The acrylic resin pellets (1A) produced in Production Example 1 were melt extruded at 270 ° C. using a single-screw extruder equipped with a polymer filter (filtration accuracy: 5 μm) and a T-die at the tip to form a strip having a thickness of 220 μm. A film was formed. Next, the formed film is continuously supplied to an oven longitudinal stretching machine following melt extrusion, and stretched at a stretching temperature of 142 ° C. in the longitudinal direction of the film (flow direction during melt extrusion). The film was stretched (longitudinal stretching) at a magnification of 1.5. Further, the film after longitudinal stretching was continuously supplied to a tenter transverse stretching machine, and stretched in the width direction (lateral stretching) at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times. In this way, a retardation film (thickness: 58 μm) made of an acrylic resin and having no easy adhesion layer was obtained.

(Comparative Example 2)
The acrylic resin pellets (1A) produced in Production Example 1 were melt extruded at 270 ° C. using a single-screw extruder equipped with a polymer filter (filtration accuracy: 5 μm) and a T-die at the tip to form a strip having a thickness of 220 μm. A film was formed. Next, the formed film is continuously supplied to an oven longitudinal stretching machine following melt extrusion, and stretched at a stretching temperature of 142 ° C. in the longitudinal direction of the film (flow direction during melt extrusion). The film was stretched (longitudinal stretching) at a magnification of 1.5.

  Further, the film after longitudinal stretching was continuously supplied to a tenter transverse stretching machine, and stretched in the width direction (lateral stretching) at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times. And continuously, the thickness of the coating film after drying the easy-adhesion composition (1B) prepared in Production Example 6 by the gravure coating method is 350 nm on one main surface of the acrylic resin film after transverse stretching. After being coated in such a manner, the whole is dried at 100 ° C. for 2 minutes, made of an acrylic resin, and an easy adhesion layer (thickness 350 nm) containing a urethane resin is formed on one main surface (thickness) 58 μm).

(Comparative Example 3)
Instead of the easy-adhesive composition (1B), an easy-adhesive layer comprising an acrylic resin and containing an acrylic resin (Example 1) except that the easy-adhesive composition (3B) prepared in Production Example 8 was used. A retardation film (thickness: 58 μm) having a thickness of 350 nm formed on one main surface was obtained.

(Example 8)
A single-screw extruder (φ = 90 mm, L / D = 32) equipped with a polymer filter (filtration accuracy 5 μm) and a T-die (width 1500 mm) at the tip of the acrylic resin pellet (1A) produced in Production Example 1 Was used to melt and extrude at 270 ° C. to form a strip-shaped film having a thickness of 220 μm. At that time, the treatment speed was 200 kg / hour in terms of the amount of resin. Next, the formed film is continuously supplied to an oven longitudinal stretching machine following melt extrusion, and the film is longitudinally processed (flow direction during melt extrusion, longitudinal direction of a strip-shaped film). The film was stretched at a stretching temperature of 142 ° C. and a stretching ratio of 1.5 times (longitudinal stretching).

  Furthermore, the thickness of the coating film after drying the easy-adhesive composition (1B) prepared in Production Example 6 on the one main surface of the acrylic resin film after longitudinal stretching by the gravure coating method is 1050 nm. After being applied to (in-line coating), the acrylic resin film is supplied to a tenter transverse stretching machine as it is, and stretched in the width direction (lateral stretching) at a stretching temperature of 132 ° C. and a stretching ratio of 3.0 times to form a roll. The film was wound up. In this way, a retardation film roll (thickness of the film) made of an acrylic resin and having an easy adhesion layer (thickness 350 nm) containing urethane resin and fine particles having an average primary particle diameter of 0.28 μm formed on one main surface. 58 μm in width, 1340 mm in width, and 4000 m in length in the longitudinal direction of the film).

Example 9
Instead of the easy-adhesive composition (1B), it was made of an acrylic resin in the same manner as in Example 8 except that the easy-adhesive composition (2B) prepared in Production Example 7 was used, and the urethane resin and the average primary particle size were A retardation film roll (film thickness: 58 μm, width: 1340 mm, length in the longitudinal direction of the film: 4000 m) having an easy adhesion layer (thickness: 350 nm) containing fine particles of 0.11 μm formed on one main surface was obtained. .

(Example 10)
Instead of the easy-adhesive composition (1B), it was made of an acrylic resin in the same manner as in Example 8 except that the easy-adhesive composition (4B) prepared in Production Example 9 was used, and the urethane resin and the average primary particle size were A retardation film roll (film thickness: 58 μm, width: 1340 mm, length in the longitudinal direction of the film: 4000 m) having an easy-adhesion layer (thickness: 350 nm) containing fine particles of 0.15 μm formed on one main surface was obtained. .

  About the structure of the retardation film produced in each Example and Comparative Example, and the Example, the wetting tension of the acrylic resin film surface after longitudinal stretching, and the wetting tension of the acrylic resin film surface after transverse stretching for the Comparative Example, It is shown in Table 1 below.

  The production conditions of the retardation film in each example and comparative example are shown in Table 2 below.

  The properties of the retardation film and retardation film roll produced in each example and comparative example are shown in Table 3 below. The in-plane retardation Re and the thickness direction retardation Rth are actually measured values.

  As shown in Table 3, the retardation film of Example 1 having an easy-adhesion layer was produced under the same stretching conditions and had the same in-plane retardation and thickness direction as Comparative Example 1 without the easy-adhesion layer. The phase difference is shown. That is, it turned out that the easily bonding layer in the retardation film of Example 1 does not affect the retardation which retardation film itself shows. On the other hand, in Comparative Example 2 in which an easy-adhesion layer was formed by applying a urethane resin dispersion to the biaxially stretched film, the in-plane retardation decreased from 105 nm to 101 nm. In addition to this, the easy-adhesion layer of the retardation film produced in each Example was excellent in adhesiveness unlike the easy-adhesion layer of the retardation film produced in Comparative Examples 2 and 3. Moreover, in Example 8 in which the easy-adhesion layer containing fine particles having an average primary particle diameter exceeding 200 nm was formed, the blocking resistance was good.

  The retardation film obtained by the production method of the present invention is suitable for use in an image display device such as an LCD.

Claims (5)

On the surface of an acrylic resin film containing a (meth) acrylic polymer having a ring structure in the main chain as a main component, a dispersion of urethane resin is applied to form a coating film of the dispersion,
The acrylic resin film on which the coating film is formed is stretched in a heating atmosphere, and the retardation film is formed by stretching the acrylic resin film, and the retardation film is heat-treated by heat of the heating atmosphere. Forming an easy-adhesion layer containing the urethane resin on the surface of
The dispersion contains fine particles;
The acrylic resin film of coating a dispersion I is strip-like uniaxially stretched film der, stretching direction of the acrylic resin film before applying the dispersion, a flow direction at the time of film formation of the film,
The direction of stretching under heating atmosphere, I the direction der perpendicular in the plane of the film with respect to the extending direction of the acrylic resin film before applying the dispersion, the width direction of the acrylic resin film And
The manufacturing method of the retardation film which has an easily bonding layer which forms the said retardation film whose in-plane retardation with respect to the light of wavelength 589nm is 10 nm or more. The average primary particle size of the fine particles exceeds 200 nm, method for producing a retardation film having an easy adhesion layer according to claim 1.   The manufacturing method of the retardation film which has an easily bonding layer of Claim 1 in which the said dispersion contains a crosslinking agent.   The retardation film having an easy-adhesion layer according to claim 1, wherein the wetting tension of the surface of the acrylic resin film before application of the dispersion is less than 40 mN / m, measured in accordance with JIS K6768. Manufacturing method. While conveying the acrylic resin film before Symbol strip in the longitudinal direction of the film, to form a coating film of the dispersion on the surface of the film, stretching the acrylic resin film formed with the coating film in a heated atmosphere Forming the belt-like retardation film in which an easy-adhesion layer containing the urethane resin is formed on the surface,
The manufacturing method of the retardation film which has the easily bonding layer of Claim 1 which winds the formed said retardation film around a roll, and obtains the said roll-shaped retardation film.