JP2008046196A - Stacked film for lens shape impartation and lens film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a base material film for lens shape impartation hard to be scratched, hard to be cracked, and also having excellent dimensional stability, and to provide a lens film at a high yield using the base material film. <P>SOLUTION: A stacked film in which at least either side of the main layer made of a transparent thermoplastic resin having a deflection temperature under a load of ≥100°C is stacked with a surface layer made of a methacrylic resin, the thickness of the main layer is ≥10 μm, and also, the thickness of the whole is 50 to 250 μm is used as a base material film for lens shape impartation. A lens shape is imparted to the surface of the base material film so as to obtain a lens film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a laminated film used as a base film for shaping a lens shape on its surface to obtain a lens film. The present invention also relates to a lens film in which a lens shape is formed on the surface of the laminated film.

  A resin lens sheet is useful as a member of a screen of a transmissive display device or a backlight of a liquid crystal display device. Generally, (1) a method of shaping a lens shape on the surface of a substrate sheet by press molding, (2) A method in which a raw material resin is formed into a sheet by extrusion molding and a lens shape is imparted to the surface thereof. (3) A lens layer is formed on the surface of the substrate sheet by an ultraviolet curable resin or an electron beam curable resin. It is manufactured by the method etc. Among these, the method (1) has the advantage that it is more adaptable to various lens shapes than the methods (2) and (3), and does not require large or expensive equipment. Yes. And as the base material sheet | seat, sheets, such as a polystyrene resin, polyolefin resin, an acrylic resin, polycarbonate resin, a vinyl chloride resin, are used (for example, refer patent document 1).

JP-A-11-183707 (paragraph 0005)

  The conventional base sheet has a problem in that the yield is lowered because the lens shape is molded or the front and back of the lens are easily scratched or cracked. Particularly, in recent years, with the increase in image quality of display devices, there has been a demand for finer pitch of lenses. To cope with this, if a thin film is used as a base sheet, the above problem is likely to occur. Even fine scratches and cracks can be a problem, and the problem is even greater. In addition, with the improvement of display device reliability, there is a strong demand for durability reliability against the lens film usage environment, and the base film has high dimensions in addition to being difficult to scratch and cracking. Stability is required. Then, the objective of this invention is providing the base film for lens shape shaping which is hard to be damaged, is hard to break, and is excellent in dimensional stability. And it is in providing a lens film with a sufficient yield using this base film.

  As a result of intensive studies, the present inventor has found that a laminated film having a predetermined layer configuration is suitable as the substrate film, and has completed the present invention. That is, in the present invention, a surface layer made of methacrylic resin is laminated on at least one surface of a main layer made of a transparent thermoplastic resin having a deflection temperature under load of 100 ° C. or more, and the thickness of the main layer is 10 μm. It is the above and provides the laminated film for lens shape shaping | molding whose whole thickness is 50-250 micrometers. Moreover, according to this invention, the lens film by which the lens shape is shaped on the surface of this laminated film is also provided.

  According to the present invention, it is possible to obtain a laminated film for lens shape shaping that is difficult to be scratched, hardly cracked, and excellent in dimensional stability, and a lens film can be obtained with a high yield.

  Hereinafter, the present invention will be described in detail. The laminated film of the present invention is a laminated film used as a base film for obtaining a lens film by shaping a lens shape on the surface thereof, on at least one surface of a main layer made of a transparent thermoplastic resin, A surface layer made of methacrylic resin is laminated.

  As the transparent thermoplastic resin constituting the main layer, one having a deflection temperature under load of 100 ° C. or higher is used. By constituting the main layer with such a specific material, the dimensional stability of the obtained laminated film is enhanced. By using this as a base film, the dimensional stability is high, and the lens shape is not easily disturbed. A lens film can be obtained with good yield.

  The deflection temperature under load of the transparent thermoplastic resin is preferably 110 ° C. or higher, and is usually 150 ° C. or lower. The deflection temperature under load can be measured according to ASTM D648.

  The type of the transparent thermoplastic resin can be appropriately selected from those having the predetermined load deflection temperature. From the viewpoint of transparency, polycarbonate resins and polycyclic olefin resins are preferably used, and polycarbonate resins are particularly preferably used.

  The polycarbonate resin may be obtained by polymerizing a dihydric phenol and a carbonylating agent by an interfacial polycondensation method or a melt transesterification method, or by polymerizing a carbonate prepolymer by a solid phase transesterification method. Alternatively, a cyclic carbonate compound may be polymerized by a ring-opening polymerization method.

  Examples of dihydric phenols used here include hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis {(4-hydroxy-3,5-dimethyl) phenyl} methane 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A), 2 , 2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dimethyl) phenyl} propane, 2,2-bis {(4-hydroxy- 3,5-dibromo) phenyl} propane, 2,2-bis {(3-isopropyl-4-hydroxy) phenyl} propane, 2,2 Bis {(4-hydroxy-3-phenyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3-methylbutane, 2,2-bis ( 4-hydroxyphenyl) -3,3-dimethylbutane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4- Hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis {(4 Hydroxy-3-methyl) phenyl} fluorene, α, α′-bis (4-hydroxyphenyl) -o-diisopropylbenzene, α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene, α, α ′ -Bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfoxide 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ester, etc. It can also be used.

  Among them, bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3 -Methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) −3,3,5-trimethylcyclohexane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene are preferably used. In particular, bisphenol A alone or 1,1-bis (4-hydroxy) is used. Phenyl) -3,3,5-trimethylcyclohexane and bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl } Combination with at least one selected from propane and α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene is preferred.

  Examples of the carbonylating agent include carbonyl halides such as phosgene, carbonate esters such as diphenyl carbonate, and haloformates such as dihaloformates of dihydric phenols.

  The polycyclic olefin resin is a polymer having a cyclic olefin as a main monomer. Examples of the cyclic olefin include polycyclic cyclic olefins such as norbornene, monocyclic cyclic olefins, cyclic conjugated dienes, And vinyl alicyclic hydrocarbons. Further, a hydrogenated product of a polymer of these cyclic olefins can also be used. Among these, from the viewpoint of transparency, a norbornene polymer hydrogenated product, a vinyl alicyclic hydrocarbon polymer, and a hydrogenated product thereof are preferable, and a norbornene polymer hydrogenated product is particularly preferable.

  The transparent thermoplastic resin may contain other components as necessary, such as rubber particles, UV absorbers, organic dyes, inorganic dyes, pigments, antioxidants, antistatic agents, surfactants, etc. And you may comprise a main layer with the composition. In this case, the deflection temperature under load as the composition is 100 ° C. or higher, preferably 110 ° C. or higher, and usually 150 ° C. or lower.

  The methacrylic resin constituting the surface layer is a polymer mainly composed of methacrylic acid ester, and may be a homopolymer of methacrylic acid ester, or 50 wt% or more of methacrylic acid ester and other monomers 50 It may be a copolymer with a weight percent or less. Here, as the methacrylic acid ester, an alkyl ester of methacrylic acid is usually used.

  The preferred monomer composition of the methacrylic resin is 50 to 100% by weight of alkyl methacrylate, 0 to 50% by weight of alkyl acrylate, and 0 to 49% by weight of other monomers based on all monomers. More preferably, the alkyl methacrylate is 50 to 99.9% by weight, the alkyl acrylate is 0.1 to 50% by weight, and other monomers are 0 to 49% by weight.

  Here, examples of the alkyl methacrylate include methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, and the like. The alkyl group usually has 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. It is. Of these, methyl methacrylate is preferably used.

  Examples of alkyl acrylates include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like. The alkyl group usually has 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms. is there.

  The monomer other than alkyl methacrylate and alkyl acrylate may be a monofunctional monomer, that is, a compound having one polymerizable carbon-carbon double bond in the molecule, or a polyfunctional monofunctional monomer. Although it may be a monomer, that is, a compound having at least two polymerizable carbon-carbon double bonds in the molecule, a monofunctional monomer is preferably used. Examples of this monofunctional monomer include aromatic alkenyl compounds such as styrene, α-methylstyrene and vinyltoluene, and alkenyl cyan compounds such as acrylonitrile and methacrylonitrile. Examples of polyfunctional monomers include polyunsaturated carboxylic acid esters of polyhydric alcohols such as ethylene glycol dimethacrylate, butanediol dimethacrylate, trimethylolpropane triacrylate, allyl acrylate, allyl methacrylate, and cinnamon. Alkenyl esters of unsaturated carboxylic acids such as allyl acid, polyalkenyl esters of polybasic acids such as diallyl phthalate, diallyl maleate, triallyl cyanurate, triallyl isocyanurate, aromatic polyalkenyl compounds such as divinylbenzene, etc. Can be mentioned.

  In addition, as for said alkyl methacrylate, alkyl acrylate, and monomers other than these, respectively, you may use those 2 or more types as needed.

  The methacrylic resin preferably has a glass transition temperature of 40 ° C. or higher, more preferably 60 ° C. or higher, from the viewpoint of heat resistance of the laminated film. This glass transition temperature can be appropriately set by adjusting the type of monomer and the ratio thereof.

  The methacrylic resin can be prepared by polymerizing the monomer component by a method such as suspension polymerization, emulsion polymerization or bulk polymerization. At that time, in order to obtain a suitable glass transition temperature or to obtain a viscosity showing a moldability to a suitable laminated film, it is preferable to use a chain transfer agent during the polymerization. The amount of the chain transfer agent may be appropriately determined according to the type of monomer and the ratio thereof.

  It is desirable from the viewpoint of flexibility and moldability of the resulting laminated film that rubber particles are blended in the methacrylic resin and the surface layer is constituted by the composition. Here, as the rubber particles, for example, acrylic, butadiene, styrene-butadiene, and the like can be used. Among these, acrylic rubber particles are preferably used from the viewpoint of weather resistance.

  The acrylic rubber particle is a particle containing an elastic polymer mainly composed of an acrylate ester as a rubber component, and may be a particle having a single layer structure made of only this elastic polymer, or a layer of this elastic polymer. However, in terms of the surface hardness of the laminated film, particles having a multilayer structure are preferable. The elastic polymer may be a homopolymer of an acrylate ester or a copolymer of 50% by weight or more of an acrylate ester and 50% by weight or less of other monomers. . Here, as the acrylic ester, an alkyl ester of acrylic acid is usually used.

  The preferable monomer composition of the elastic polymer mainly composed of acrylic acid ester is 50 to 99.9% by weight of alkyl acrylate based on all monomers, and 0 to 49% of other monofunctional monomers. 0.9% by weight and 0.1 to 10% by weight of the polyfunctional monomer.

  Here, the example of alkyl acrylate is the same as the example of alkyl acrylate mentioned above as a monomer component of methacrylic resin, The carbon number of the alkyl group is 1-8 normally, Preferably it is 4-8. is there.

  In addition, the monofunctional monomer other than the alkyl acrylate can be an alkyl methacrylate or other monofunctional monomer, and examples thereof include those of the alkyl methacrylate described above as the monomer component of the methacrylic resin. This is the same as the examples and examples of monofunctional monomers other than alkyl methacrylate and alkyl acrylate.

  Examples of the polyfunctional monomer are the same as the examples of the polyfunctional monomer previously mentioned as the monomer component of the methacrylic resin, and among them, alkenyl esters of unsaturated carboxylic acids and polybasic acids. Polyalkenyl esters are preferably used.

  In addition, as for said alkyl acrylate, the other monofunctional monomer, and a polyfunctional monomer, you may use those 2 or more types as needed, respectively.

  When the acrylic rubber particles having a multilayer structure are used, a preferable example is one having a polymer layer mainly composed of methacrylic acid ester outside the elastic polymer layer mainly composed of acrylate ester. That is, an at least two-layer structure in which an elastic polymer mainly composed of an acrylate ester is used as an inner layer and a polymer mainly composed of a methacrylic acid ester is used as an outer layer. Here, as the methacrylic acid ester which is a monomer component of the polymer in the outer layer, alkyl methacrylate is usually used. The outer layer polymer is usually formed at a ratio of 10 to 400 parts by weight, preferably 20 to 200 parts by weight with respect to 100 parts by weight of the inner layer elastic polymer. By setting the polymer of the outer layer to 10 parts by weight or more with respect to 100 parts by weight of the elastic polymer of the inner layer, the elastic polymer is hardly aggregated, and the transparency of the laminated film is improved.

  The preferable monomer composition of the polymer of the outer layer is 50 to 100% by weight of alkyl methacrylate, 0 to 50% by weight of alkyl acrylate based on all monomers, and 0 to 50% by weight of other monomers. 49% by weight.

  Here, the example of alkyl methacrylate is the same as the example of alkyl methacrylate previously mentioned as a monomer component of a methacryl resin, The carbon number of the alkyl group is 1-8 normally, Preferably it is 1-4. is there. Of these, methyl methacrylate is preferably used.

  Moreover, the example of alkyl acrylate is the same as that of the alkyl acrylate mentioned above as a monomer component of a methacryl resin previously, The carbon number of the alkyl group is 1-8 normally, Preferably it is 1-4. .

  Monomers other than alkyl methacrylate and alkyl acrylate may be monofunctional monomers or polyfunctional monomers, but monofunctional monomers are preferably used. Examples of this monofunctional monomer are the same as the examples of monofunctional monomers other than the alkyl methacrylate and alkyl acrylate mentioned above as the monomer component of the methacrylic resin, Examples of the monomer are the same as those of the polyfunctional monomer mentioned above as the monomer component of the methacrylic resin.

  In addition, as for said alkyl methacrylate, alkyl acrylate, and monomers other than these, respectively, you may use those 2 or more types as needed.

  Further, as a preferred example of the acrylic rubber particles having a multilayer structure, a polymer layer mainly composed of a methacrylic acid ester is further provided inside the elastic polymer layer mainly composed of an acrylate ester which is the inner layer of the two-layer structure. In other words, the polymer mainly composed of methacrylic acid ester is used as the inner layer, the elastic polymer mainly composed of acrylate ester is used as the intermediate layer, and the polymer mainly composed of the methacrylic acid ester is used as the outer layer. There can also be mentioned at least a three-layer structure. Here, as a methacrylic acid ester which is a monomer component of the polymer of the inner layer, alkyl methacrylate is usually used. The polymer of the inner layer is usually formed at a ratio of 10 to 400 parts by weight, preferably 20 to 200 parts by weight, with respect to 100 parts by weight of the elastic polymer of the intermediate layer.

  The preferable monomer composition of the polymer of the inner layer is 70 to 100% by weight of alkyl methacrylate and 0 to 30% by weight of other monomers based on all monomers.

  Here, the example of alkyl methacrylate is the same as the example of alkyl methacrylate previously mentioned as a monomer component of a methacryl resin, The carbon number of the alkyl group is 1-8 normally, Preferably it is 1-4. is there. Of these, methyl methacrylate is preferably used.

  The monomer other than alkyl methacrylate may be an alkyl acrylate or other monofunctional monomer, or may be a polyfunctional monomer. And examples of this monofunctional monomer are the same as the examples of alkyl acrylates mentioned above as monomer components of methacrylic resins, and examples of monofunctional monomers other than alkyl methacrylates and alkyl acrylates. In addition, examples of the polyfunctional monomer are the same as the examples of the polyfunctional monomer previously mentioned as the monomer component of the methacrylic acid resin.

  In addition, as for said alkyl methacrylate and monomers other than these, respectively, you may use those 2 or more types as needed.

  Acrylic rubber particles can be prepared by polymerizing the monomer component of the above-mentioned elastic polymer mainly composed of an acrylate ester by at least one stage reaction by an emulsion polymerization method or the like. At this time, as described above, when a polymer layer mainly composed of methacrylic acid ester is formed outside the elastic polymer layer, the monomer component of the outer layer polymer is added to the elastic polymer layer. What is necessary is just to graft to the said elastic polymer by making it superpose | polymerize by reaction of at least 1 step | paragraph by emulsion polymerization method etc. in presence of a polymer. Further, as described above, when a polymer layer mainly composed of methacrylic acid ester is formed inside the elastic polymer layer, first, the monomer component of the polymer in the inner layer is Polymerization is carried out by at least one stage reaction by emulsion polymerization or the like, and then the monomer component of the elastic polymer is polymerized by at least one stage reaction by emulsion polymerization or the like in the presence of the resulting polymer. In the presence of the resulting elastic polymer, the monomer component of the outer layer polymer is polymerized in an at least one-stage reaction by an emulsion polymerization method or the like. To be grafted to the elastic polymer. When the polymerization of each layer is performed in two or more stages, it is sufficient that the monomer composition as a whole is within a predetermined range, not the monomer composition of each stage.

  Regarding the particle diameter of the acrylic rubber particles, the average particle diameter of the elastic polymer layer mainly composed of acrylic acid ester in the rubber particles is preferably 0.05 to 0.4 μm, and more preferably 0. The thickness is 1 to 0.3 μm, more preferably 0.14 to 0.25 μm. If the average particle size is too large, the transparency of the laminated film is lowered, which is not preferable. On the other hand, when the average particle size is too small, the surface hardness of the laminated film is lowered and easily scratched, or the flexibility of the laminated film is lowered and easily broken, which is not preferable.

  The average particle diameter was determined by mixing acrylic rubber particles with a methacrylic resin to form a film, dyeing the elastic polymer layer with ruthenium oxide in the cross section, and observing with an electron microscope. It can be determined from the diameter. That is, when acrylic rubber particles are mixed with methacrylic resin and the cross section thereof is dyed with ruthenium oxide, the methacrylic resin of the parent phase is not dyed, and the polymer mainly composed of methacrylic acid ester is outside the elastic polymer layer. If there is a layer, the polymer of this outer layer is not dyed, only the elastic polymer layer is dyed. The diameter can be determined. When a polymer layer mainly composed of methacrylic acid ester is present inside the elastic polymer layer, the polymer of the inner layer is not dyed and the outer elastic polymer layer is dyed 2 In this case, the outer diameter of the two-layer structure, that is, the outer diameter of the elastic polymer layer may be considered.

  The blending ratio of the methacrylic resin and the acrylic rubber particles is preferably 20 to 95 parts by weight of the methacrylic resin and 5 to 80 parts by weight of the acrylic rubber particles based on the total of 100 parts by weight of both. When the ratio of the methacrylic resin is too small and the ratio of the acrylic rubber particles is too large, the surface hardness of the laminated film is lowered and easily damaged, and the product appearance after shape transfer is deteriorated. On the other hand, when the proportion of the methacrylic resin is too large and the proportion of the acrylic rubber particles is too small, the flexibility of the laminated film is lowered and it becomes easy to break.

  The amount of the elastic polymer mainly composed of acrylic ester in the acrylic rubber particles is preferably 5 to 35 parts by weight based on the total of 100 parts by weight of the methacrylic resin and the acrylic rubber particles. More preferred are parts by weight. If the amount of the elastic copolymer is 5 parts by weight or more per 100 parts by weight of the total of methacrylic resin and acrylic rubber particles, the film forming property can be improved without the laminated film itself becoming brittle. On the other hand, if the amount of the elastic copolymer is 35 parts by weight or less per 100 parts by weight of the total of methacrylic resin and acrylic rubber particles, the transparency and surface hardness of the laminated film can be improved.

  In addition to rubber particles, other components such as UV absorbers, organic dyes, inorganic dyes, pigments, antioxidants, antistatic agents, surfactants and the like are blended into the methacrylic resin as necessary. May be.

  By forming a transparent thermoplastic resin having a deflection temperature under load of 100 ° C. or higher, which is a constituent material of the main layer, and a methacrylic resin, which is a constituent material of the surface layer, into a laminated film, at least one of the main layers made of the transparent resin is formed. By forming a surface layer made of methacrylic resin on the surface, the laminated film for lens shape shaping of the present invention is obtained. The method for forming this laminated film is appropriately selected. For example, after one resin is formed into a film by an extrusion molding method, the other resin is melt-extruded and laminated while the other resin is melt-extruded, or both resins are formed into a film. In particular, a laminate method in which heat is applied is used. In particular, both resins are melted, laminated in a molten state using a feed block method or a multi-manifold method, extruded, and sandwiched between a pair of mirror rolls and molded. An extrusion method is advantageously employed from the viewpoint of surface smoothness and thickness uniformity of the film.

  The thus obtained laminated film for lens shape shaping has a thickness of 50 to 250 μm, preferably 60 to 200 μm, more preferably 75 to 150 μm. A too thick laminated film is difficult to cope with the fine pitch of the lens, and since the time required for heating becomes longer when shaping the lens shape, the production efficiency of the lens film is reduced, and further, the per unit area is reduced. Since the unit price increases, it becomes economically disadvantageous. On the other hand, in the case of a very thin laminated film, it is difficult to form a laminated film by extrusion molding due to mechanical restrictions, and it is also difficult to mold a lens shape due to mechanical restrictions. The thickness of the laminated film can be adjusted by adjusting the film forming speed, the thickness of the outlet of the T-shaped die, the gap between the rolls, and the like.

  The main layer made of the transparent resin has a thickness of 10 μm or more, preferably 30 μm, and is advantageously 30% or more of the total thickness of the laminated film. If the main layer is too thin, dimensional stability tends to decrease. The surface layer made of methacrylic resin is preferably disposed evenly on both sides of the main layer in consideration of thermal behavior. Moreover, in order to efficiently express the high surface hardness of the methacrylic resin, it is preferable that each layer has a thickness of 20 μm or more when arranged on both surfaces of the main layer.

  By using the laminated film as a base film and shaping the lens shape on the surface thereof, it is possible to suppress the generation of scratches and cracks and to obtain a lens film excellent in dimensional stability with a high yield. This shaping can be performed by press molding using a shaping plate or shaping roll having a lens mold on the surface, that is, a lens shape opposite to that of the shaping. Specifically, if a single-sided lens film is to be obtained, the substrate film is heated above its glass transition temperature and sandwiched between the shaping plate and the mirror plate, or between the shaping roll and the mirror roll. It is good to insert between and press. Here, when using a base film having a surface layer made of methacrylic resin on one side of the main layer made of transparent resin, the surface It is better to shape the lens shape in the layer. If a double-sided lens film is to be obtained, the substrate film is heated above its glass transition temperature and sandwiched between the shaping plate and the shaping plate, or between the shaping roll and the shaping roll. In this case, it is preferable to use a base film having a surface layer made of methacrylic resin on both sides of the main layer made of transparent resin. In addition, it replaces with heating a base film, or in addition to heating a base film, it is also possible to heat a shaping board or a shaping roll.

  Examples of the shape of the molded lens include a Fresnel lens, a lenticular lens, and a prism lens, but the present invention is advantageously applied particularly when the shape of the prism lens is molded. In this case, it is preferable that the pitch of the lens shape is 200 μm or less and the height is 100 μm or less from the viewpoint of the fine pitch of the lens that is required with the recent improvement in image quality of display devices.

  Examples of the present invention will be described below, but the present invention is not limited thereto. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

  As the polycarbonate resin, Caliber 301-10 manufactured by Sumitomo Dow Co., Ltd. was used. This polycarbonate resin has a deflection temperature under load of 135 ° C. measured at a bending stress of 1.82 MPa in accordance with ASTM D648.

  As the methacrylic resin, pellets of a thermoplastic polymer (glass transition temperature 104 ° C.) obtained by bulk polymerization of a monomer composed of 97.8% methyl methacrylate and 2.2% methyl acrylate were used. This glass transition temperature is an extrapolated glass transition start temperature obtained at a heating rate of 10 ° C./min by differential scanning calorimetry according to JIS K7121: 1987.

  As the acrylic rubber particles (A), the innermost layer is a hard polymer obtained by polymerization of a monomer composed of 93.8% methyl methacrylate, 6% methyl acrylate, and 0.2% allyl methacrylate, The intermediate layer is an elastic polymer obtained by polymerization of a monomer composed of 81% butyl acrylate, 17% styrene and 2% allyl methacrylate, and the outermost layer is 94% methyl methacrylate and 6% methyl acrylate. The weight ratio of the innermost layer / intermediate layer / outermost layer is 35/45/20, and the average particle diameter of the elastic polymer layer of the intermediate layer A rubber particle having a spherical three-layer structure by an emulsion polymerization method having a diameter of 0.22 μm was used.

  The acrylic rubber particles (B) have basically the same composition as the acrylic rubber particles (A), but by changing the polymerization conditions, the average particle diameter of the elastic polymer layer of the intermediate layer becomes 0.14 μm. Rubber particles having a spherical three-layer structure were used.

  The average particle diameter of the elastic polymer layer of the intermediate layer in the acrylic rubber particles (A) and (B) was measured by the following method.

(Measurement of average particle diameter of elastic polymer layer)
Acrylic rubber particles are mixed with a methacrylic resin to form a film, and the resulting film is cut into an appropriate size, and the slice is immersed in a 0.5% aqueous ruthenium tetroxide solution at room temperature for 15 hours. The polymer layer was dyed. Further, the sample was cut to a thickness of about 80 nm using a microtome, and then photographed with a transmission electron microscope. After randomly selecting 100 dyed elastic copolymer layers from this photograph and calculating the particle diameter of each, the number average value was taken as the average particle diameter.

Examples 1-6, Comparative Example 1
Methacrylic resin pellets and acrylic rubber particles (A) or (B) were mixed at a ratio shown in Table 1 with a supermixer and melt-kneaded with a twin screw extruder to obtain pellets of a methacrylic resin composition. Next, the polycarbonate resin was melted with a 65 mmφ single screw extruder manufactured by Toshiba Machine Co., Ltd., and the pellets of the methacrylic resin composition were melted with a 45 mmφ single screw extruder manufactured by Toshiba Machine Co., Ltd. And extruded through a T-shaped die having a set temperature of 275 ° C., and the resulting film was sandwiched between a pair of metal rolls having smooth surfaces. Thus, a laminated film having a three-layer structure (Examples 1 to 5, Comparative Example 1) or a two-layer structure (Example 6) shown in Table 1 was manufactured, and the following evaluation was performed. The results are shown in Table 1.

[Flexibility test]
According to JIS K5600-5-1: 1999, the bending resistance of the film was evaluated. The test piece was not broken and the flexibility was good, and the test piece was broken and the flexibility was x. did.

〔surface hardness〕
The pencil hardness of the film was measured according to JIS K5600-5-4: 1999.

(Dimensional stability)
After the film was left in an oven at 120 ° C. for 1 hour, the thermal shrinkage rate was determined by the following formula. The smaller this value, the better the dimensional stability.
Thermal contraction rate (%) = {(A−B) / A} × 100
A: Dimensions before test B: Dimensions after test

(Shape transfer)
Using a plate-shaped press mold having a prism lens mold with a pitch of 50 μm and a height of 25 μm on the surface, the film was pressed at a mold temperature of 220 ° C. and a press pressure of 100 kg / cm ² , and the lens obtained after cooling The film was observed. The case where the lens shape was almost completely transferred was indicated by ◯, and the case where the lens shape was not sufficiently transferred was indicated by ×. In the case where a defect such as a crack occurred at the time of peeling from the mold after transfer, it was also marked as x.

  In the case of a laminated film having a two-layer structure in which a methacrylic resin composition layer (surface layer) is formed only on one side of the polycarbonate resin layer (main layer) obtained in Example 6, the surface hardness and shape transferability are The resin composition layer (surface layer) was evaluated.

Comparative Example 2
Methacrylic resin pellets and acrylic rubber particles (A) were mixed at a ratio shown in Table 1 with a supermixer and melt-kneaded with a twin screw extruder to obtain pellets of a methacrylic resin composition. Next, the pellets of the methacrylic resin composition were melted with a 65 mmφ single screw extruder manufactured by Toshiba Machine Co., Ltd., and extruded through a T-type die having a set temperature of 275 ° C., and the resulting film-like product was smooth on a pair of surfaces. Molded by sandwiching between metal rolls. Thus, a single-layer acrylic film having the thickness shown in Table 1 was produced, and the same evaluation as above was performed. The results are shown in Table 1.
Comparative Example 3
Polycarbonate resin is melted with a 65 mmφ single screw extruder manufactured by Toshiba Machine Co., Ltd., extruded through a T-shaped die with a set temperature of 275 ° C., and the resulting film is placed between a pair of smooth metal rolls And then molded. Thus, a single-layer polycarbonate film having the thickness shown in Table 1 was produced, and the same evaluation as above was performed. The results are shown in Table 1.

Claims (9)

  A surface layer made of a methacrylic resin is laminated on at least one surface of a main layer made of a transparent thermoplastic resin having a deflection temperature under load of 100 ° C. or more, and the thickness of the main layer is 10 μm or more, and the whole The thickness of the lens is 50 to 250 μm, a lens shape shaping laminated film.   The laminated film according to claim 1, wherein the thermoplastic resin is a polycarbonate resin.   The methacrylic resin is a polymer obtained by polymerizing 50 to 100% by weight of alkyl methacrylate, 0 to 50% by weight of alkyl acrylate, and 0 to 49% by weight of other monomers. The laminated film according to 1 or 2.   The laminated film according to claim 1, wherein the surface layer is made of methacrylic resin and acrylic rubber particles.   Acrylic rubber particles in a proportion of 50 to 99.9% by weight of alkyl acrylate, 0 to 49.9% by weight of other monofunctional monomers, and 0.1 to 10% by weight of polyfunctional monomers The laminated film according to claim 4, wherein the laminated film is a particle containing an elastic polymer obtained by polymerization.   Acrylic rubber particles have a ratio of 50 to 100% by weight of alkyl methacrylate, 0 to 50% by weight of alkyl acrylate, and 0 to 49% by weight of other monomers on the outside of the elastic polymer layer. The laminated film according to claim 5, which is a particle having a multi-layer structure having a polymer layer polymerized by.   A polymer layer in which acrylic rubber particles are polymerized at a ratio of 70 to 100% by weight of alkyl methacrylate and 0 to 30% by weight of other monomers inside the elastic polymer layer. The laminated film according to claim 6, which is a particle having a multilayer structure.   A lens film obtained by forming a lens shape on the surface of the laminated film according to claim 1. The lens film according to claim 8, wherein the lens shape is that of a lenticular lens, a prism lens, or a Fresnel lens.